APPENDIX 7 NOISE. Specialist. Mr Adrian Jongens Jongens Keet Associates. Peer Review. Mr Francois Malherbe Acoustic Consultancy

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1 APPENDIX 7 NOISE Specialist Mr Adrian Jongens Jongens Keet Associates Peer Review Mr Francois Malherbe Acoustic Consultancy

2 JKA JONGENS KEET ASSOCIATES ACOUSTICAL ENGINEERING CONSULTANTS Telephone: Facsimile: A.W.D. Jongens 8 Wingerd Avenue 7806 CONSTANTIA Cellphone: D. Cosijn 207 Albert Street 0181 WATERKLOOF Cellphone: Dr. W. de V. Keet P.O. Box KERNKRAG Cellphone: Architectural Acoustics Noise & Vibration Control Environmental Noise Traffic Noise Acoustical Material Research Underwater Sound Nonlinear Acoustics SPECIALIST STUDY INTO THE POTENTIAL IMPACT OF NOISE OF THE PROPOSED N1 N2 WINELANDS TOLL HIGHWAY PROJECT. Prepared for Crowther Campbell & Associates on behalf of the Protea Parkways Consortium and the South African National Roads Agency Limited July 2002

3 EXECUTIVE SUMMARY A noise impact study was conducted into a proposal to upgrade, construct and toll the N1 and N2 National Routes in the Western Cape. The impact of noise associated with the location of mainline toll plazas at proposed locations was investigated as well as that of a proposed new road bypassing Somerset West. The investigation has found that the existing impact of ambient noise levels on land adjacent to the N1 between the Durban Road and Paarl and adjacent to the N2 between Vanguard Drive and Somerset West are already unacceptably high. In most instances along the existing routes within the Concession, the relative impact of noise due to the proposed toll plazas and interchanges would be low. In certain instances the introduction of proposed interchanges is expected to have a positive impact on land close to the interchanges by eliminating interrupted traffic flow and by the on- and off-ramps providing partial screening of noise sensitive areas from the routes. These benefits would, however, be reduced unless traffic speeds are strictly enforced. Arising out of the results of the investigation it is recommended that, where possible, mainline toll plazas on freeway sections of both routes be located no less than 290 metres from the nearest noise sensitive land. Where this distance is less, noise mitigation measures in the form of 3-metre high noise barriers extending 50 metres on either side of the tollbooths should be implemented. It is recommended that ramp plazas be located at a distance of no less than 50 metres from the nearest noise sensitive land and that noise mitigation measures in the form of 3- metre high noise barriers extending 50 metres on either side of the tollbooths should be implemented The proposed new Somerset West Bypass between Helderzicht and Firlands would result in a very high noise impact necessitating noise mitigation measures in the form of a lownoise porous asphalt road surface in combination with noise barriers located close to the edge of the new road. The Proponent proposes to widen the existing N1 between Durban Road and Old Oak Road and to widen the existing N2 between Vanguard Drive and the R300 by adding a lane in each direction. Although falling outside of the concession this proposal is investigated in terms of requirements of the Noise Control Regulations applicable to the Province of the Western Cape. The existing levels of ambient noise along these sections are already unacceptably high. During the concession period the levels are anticipate to increase further. If legislation under the Noise Control Regulations is enforced, extensive noise mitigation measures would be required along these sections. It is expected that construction noise would be caused primarily by heavy-duty, earthmoving vehicles. The noise associated with the building of the tollbooths and associated structures would be typical of the construction of any new building. In all cases the noise would be of finite duration. Where construction noise is likely to intrude on adjacent noise sensitive land, it is recommended that a prohibition of any construction work outside normal working hours be written into the contractors contract.

4 TABLE OF CONTENTS. 1. INTRODUCTION DESCRIPTION OF STUDY AREAS N1 TOLL ROAD N2 TOLL ROAD ASSESSMENT OF NOISE FROM ROAD TRAFFIC CODES OF PRACTICE, LEGISLATION AND WORLD BEST PRACTICE SABS CODE OF PRACTICE Definitions Noise assessment procedure NOISE CONTROL REGULATIONS Definitions Noise control procedure WORLD HEALTH ORGANISATION AND EUROPEAN COMMUNITY WORLD BANK DISTINCTION BETWEEN SABS, NCR AND WHO STUDY APPROACH MITIGATION OF NOISE ROAD SURFACE TEXTURE NOISE BARRIERS SOUND INSULATION OF DWELLING FACADES DISTANCE SUMMARY NOISE SENSITIVE AREAS NOISE IMPACT OF TOLL PLAZAS CHARACTERISTCS OF NOISE EMANTING FROM TOLL PLAZAS N1 FREEWAY MAINLINE TOLL PLAZAS AT WESTERN END OF CONCESSION Kraaifontein west of the Brighton Road Interchange (Kraaifontein) Joostenbergvlakte west of Joostenbergvlakte Interchange Joostenbergvlakte east of Joostenbergvlakte Interchange Assessment summary: HEX RIVER POORT AND SANDHILLS TOLL PLAZAS De Wet Glen Heatlie Glen Heatlie North Sandhills Assessment summary: N1 INTERCHANGES AND RAMP PLAZAS Durban Road Interchange Okavango Road Interchange Brighton Road Interchange (Kraaifontein) Joostenbergvlakte Interchange Ramp Plaza...20

5 9.3.5 R304 (Stellenbosch) Interchange Huguenot Tunnel eastern Ramp Plaza Florence Interchange Worcester West Interchange Casino Interchange Roux overpass High Street Overpass Worcester East Interchange Further consideration for the N1 through Worcester REALIGNMENT OF THE N1 WITHIN THE HEX RIVER POORT Northern Section - Sandhills Central Section near Glen Heatlie North Southern Section Glen Heatlie WIDENING OF THE N1 BETWEEN DURBAN ROAD AND BRIGHTON ROAD (KRAAIFONTEIN) AND N2 BETWEEN VANGUARD DRIVE AND THE R MEASUREMENT AND ASSESSMENT OF EXISTING NOISE IMPACT Ambient noise levels on land adjacent to the N Tygerberg - Parc du Cap site Oakdale c/o Barnard and Springfield Roads Plattekloof - Landdros Protea Hotel Paarl Assessment: NOISE IMPACT OF ROAD WIDENING N2 TOLL ROUTE EXPLANATION OF TABLE HEADINGS AND CONTENTS N2 KHAYELITSHA MAINLINE TOLL PLAZA LOCATIONS Khayelitsha West Khayelitsha Central Khayelitsha East Assessment summary: FIRLANDS WEST AND FIRLANDS MAINLINE TOLL PLAZA LOCATIONS Firlands West Toll Plaza Firlands Toll Plaza Assessment summary: N2 HOUWHOEK PASS AND BOT RIVER MAINLINE TOLL PLAZA LOCATIONS Houwhoek Pass Bot River Assessment summary: N2 INTERCHANGES AND RAMP PLAZAS Firlands Interchange and Ramp Plazas Pineview Grabouw West Grabouw East Kromco Houwhoek Interchange Bot River Ramp Plaza N2 - BYPASS BETWEEN HELDERZICHT AND FIRLANDS Existing road traffic Alternative 1 Do nothing Alternative 2 Upgrade the T2 to Freeway Standards Alternative 3 Bypass Helderzicht to the North with the N2 relocated on a Viaduct. Beyond Victoria Street join the N2 proclaimed route...59

6 Alternative 4 Bypass Helderzicht to the South with N2 relocated through AECI property Alternatives 5, 6 and 7 - N2 on the proclaimed Route Summary discussion of the noise impact of the proposed N2 bypass along the proclaimed route of the Helderberg area MITIGATION OF ROAD NOISE BETWEEN HELDERZICHT AND FIRLANDS Receiver located 1,4 metres above ground level Receiver located 5 metres above ground level Discussion of the mitigation measures CONCLUSIONS RECOMMENDATIONS...75 REFERENCES BIBLIOGRAPHY...76

7 JKA JONGENS KEET ASSOCIATES ACOUSTICAL ENGINEERING CONSULTANTS Telephone: Facsimile: A.W.D. Jongens 8 Wingerd Avenue 7806 CONSTANTIA Cellphone: D. Cosijn 207 Albert Street 0181 Waterkloof Cellphone: Dr. W. de V. Keet P.O. Box KERNKRAG Cellphone: Architectural Acoustics Noise & Vibration Control Environmental Noise Traffic Noise Acoustical Material Research Underwater Sound Nonlinear Acoustics SPECIALIST STUDY INTO THE POTENTIAL IMPACT OF NOISE OF THE PROPOSED N1 N2 WINELANDS TOLL HIGHWAY PROJECT. 1. INTRODUCTION This report presents a description and results of a Noise Impact Assessment (referred to as NIA) of a proposal to upgrade, maintain and toll sections of the N1 and N2 National Routes in the Western Cape. The proposal has been submitted to Crowther Campbell & Associates on behalf of the Protea Parkways Consortium and the South African National Roads Agency (jointly referred to as the Proponent). 2. DESCRIPTION OF STUDY AREAS 2.1 N1 TOLL ROAD The proposed N1 toll road included in the Concession Contract extends from the Old Oak interchange, just west of the R300, along the existing N1 route to Sandhills at the start of the Hex River Valley. Two mainline toll plazas are proposed: in the vicinity of Joostenbergvlakte and between De Wet and Sandhills. One of the alternative Joostenbergvlakte toll plaza locations is located west of the Brighton Road (Kraaifontein) interchange. Two suburban residential districts of Kraaifontein, namely Windsor Park and Scottsville flank this proposed location. The other alternative locations are surrounded by open ground, away from residential dwellings. Alternatives between De Wet and Sandhills include plaza locations at De Wet, Glen Heatlie, Glen Heatlie North and Sandhills. Ramp plazas are proposed at the Joostenbergvlakte interchange with Maroela Road and Lucullus Street and on the R101 to the east of the Huguenot Tunnel. No road alignment changes are considered except in the Hex River Poort between Worcester and Sandhills. Construction of an additional two-lane carriageway along these sections of the Hex River Poort is proposed. The Proponent proposes to widen the existing N1 between Durban Road and Brighton Road (Kraaifontein) interchange by addition of a lane on the median side of each carriageway. Although outside the Concession, this section of the route is included in the NIA in accordance with the requirements of the Noise Control Regulations applicable to the Province of the Western Cape. 1

8 2.2 N2 TOLL ROAD The proposed N2 toll road included in the Concession Contract extends from just west of the R300 eastwards along the existing route to Bot River. The proposal includes the construction of a new freeway extension, on a proclaimed road reserve, that bypasses Somerset West. The proposed bypass extends from west of the suburb of Helderzicht to the foot of Sir Lowry s Pass near the intersection of the existing trunk road and Gordons Bay Road. Several alternative alignments have been proposed for the N2 bypass in the vicinity of Helderzicht. Three mainline toll plazas are proposed: in the vicinity of Khayelitsha; in the vicinity of Firlands and at Bot River. Three alternative locations are proposed in the vicinity of Khayelitsha. Two alternative locations are proposed in the vicinity of Firlands while an alternative to the Bot River toll plaza is proposed at Houwhoek Pass. The Proponent proposes to widen the existing N2 between Vanguard Drive and the R300. Although outside the Concession, this section of the route is included in the NIA in accordance with the requirements of the Noise Control Regulations applicable to the Province of the Western Cape. 3. ASSESSMENT OF NOISE FROM ROAD TRAFFIC In accordance with the Environment Conservation Act 73 of 1989, two procedures exist for assessing and controlling road traffic noise: The procedures contained in the South African Bureau of Standards Code of Practice 0328 Methods for environmental noise impact assessments. The procedures contained in the Noise Control Regulations of the Environment Conservation Act 73 of 1989 applicable to the Province of the Western Cape. The procedures, considered in greater detail in Section 4 of this report, may be summarised as follows: In accordance with procedures contained in SABS 0328, the predicted impact that the noise emanating from the proposed development would have on occupants of surrounding land is assessed by determining whether the level of the predicted noise would exceed the acceptable and/or the residual level of noise on that land and relating this excess to the probable response of a community to the noise. In terms of the Noise Control Regulations if the predicted noise due to the proposed development is likely to cause the noise level on surrounding land to exceed 65 dba, noise mitigation measures may need to be implemented to ensure that noise level on the affected land does not exceed 65 dba. 2

9 4. CODES OF PRACTICE, LEGISLATION AND WORLD BEST PRACTICE 4.1 SABS CODE OF PRACTICE Definitions Ambient noise is defined as the totally encompassing sound in a given situation at a given time, and is usually composed of sound from many sources, both near and far. It includes the noise from the noise source(s) under investigation. Residual noise is defined as the ambient noise that remains at a given position in a given situation when one or more specific noises are suppressed. A-weighted sound pressure level, L pa or L A is the sound pressure or intensity level, in decibels, using an electrical filter network in the measuring intrument corresponding with the human ear s different sensitivity to sound at different frequencies. Equivalent continuous A-weighted sound pressure level, LAeq. A formal definition is contained in SABS The term equivalent continuous may be understood to mean the average A-weighted sound level measured continuously, or calculated, over a reference time interval. Unless otherwise stipulated the reference time intervals are defined as, Daytime 06:00 to 18:00 hours, Evening 18:00 to 24:00 hours, Night time 00:00 to 06:00 hours, Weekends Saturday 12:00 to 18:00 hours and Sunday 06:00 to 18:00 hours Rating level, L r, is the equivalent continuous A-weighted sound pressure level, L Aeq, measured or calculated during a specified time interval, to which is added a correction of 5 db for any tonal character, if present. If the noise is of an impulsive nature a further correction of 5 db or a value derived in accordance with Section of the Code is added. Where neither is present, the L r is equal to the L Aeq. 18-hour L Aeq is the L Aeq averaged over an 18-hour period from 06:00 to 24:00 hours With regard to road traffic noise, the descriptor generally used is the 18-hour L Aeq instead of L r. A correction for impulsive type of sounds is generally not applied, as this is normally absent in noise emanating from road traffic. However, in the present study an impulse correction was applied in predicting the noise from toll plazas due to the impulsive type of noise emanating from vehicles passing over rumble strips often present on the approach to the tollbooths. In this report the traffic noise descriptor is the 18-hour L r with an impulse correction, if applicable. A detailed study of noise occurring at toll plazas and the derivation of the values of the applied impulse correction is contained in a separate report [4]. 3

10 4.1.2 Noise assessment procedure. In accordance with Section 7.5 of SABS 0328, the assessment of the estimated road traffic noise impact is established by determining the probable community response from Table 6 of the SABS Code of Practice 0103 for The measurement and rating of environmental noise with respect to annoyance and to speech communication. SABS 0103 covers a method of measurement and assessment of noise to determine the suitability of an environment for specific human activities with respect to possible annoyance (i.e. whether complaints could be expected). Section 8.4 of the Code states that it is highly probable that the noise is annoying or otherwise intrusive to a community, or a group of persons, if the rating level, L r, of the ambient noise (including the noise under investigation) exceeds the typical level as indicated in Table 2 of SABS 0103 or exceeds the residual noise (in the absence of the noise under investigation). Typical outdoor rating levels, L r, in dba, derived from Table 2 of SABS 0103, are: Type of district Daytime Evening, Night-time weekends Rural Suburban with little road traffic Urban Urban with some workshops, business premises & main roads Central business Industrial In accordance with Section of SABS 0328 the probable community response for various degrees of excess of the estimated future L r over the typical L r, derived from Table 6 of SABS 0103, is set out below: Excess of L r over typical or existing L r, db Probable community response 0 No observed reaction > 0 5 Sporadic complaints > 5 10 Widespread complaints > Threats of community/group action > 15 Vigorous community/group action 4.2 NOISE CONTROL REGULATIONS Definitions. In terms of Schedule 1 of the Noise Control Regulations (NCR) of the Environmental Conservation Act 1989 (Act 73 of 1989) applicable to the Province of the Western Cape, Provincial Gazette Number 5309 of 20 November 1998: controlled area means a piece of land designated by a local authority where, in the case of 4

11 (a) road traffic noise directly adjacent to a road (i) the reading on an integrating impulse sound level meter, taken outdoors at the end of a period extending from 06:00 to 24:00 while such meter is in operation, exceeds 65 dba; or (ii) the outdoor equivalent continuous A -weighted sound pressure level at a height of at least 1,2 m. but not more than 1,4 m. above the ground for a period extending from 06:00 to 24:00, as calculated in accordance with SABS 0210, and projected for a period of 15 years following the date on which the local authority makes such designation, exceeds 65 dba: Noise control procedure. In terms of Schedule 3(d) of the Act: No person shall build a road or change an existing road, or alter the speed limit on a road, if this will cause an increase in noise in or near residential areas, or offices, churches, hospitals or educational buildings, unless the need for noise control measures has been properly determined by the local authority in consultation with the road authority concerned to ensure that the land in the vicinity of that road will not be designated as a controlled area. 4.3 WORLD HEALTH ORGANISATION AND EUROPEAN COMMUNITY The World Health Organisation, WHO, summarises the thresholds for noise nuisance in terms of outdoor daytime L Aeq in residential districts as follows: At dba noise creates annoyance. At dba annoyance increases considerably. Above 65 dba constrained behaviour patterns, symptomatic of serious damage caused by noise arise. The World Health Organisation recommends a maximum outdoor daytime L Aeq of 55dBA in residential areas and schools in order to prevent significant interference with normal activities of local communities. It further recommends a maximum night time L Aeq of 45 dba outside dwellings. No distinction is made as to whether the noise originates from road traffic, from industry, or any other noise source other than air traffic noise. Countries within the European Community have either adopted or are in the process of adopting the WHO recommendations. 4.4 WORLD BANK The World Bank has adopted the WHO recommendations on maximum L Aeq in residential areas and schools. Since 1 July 1998 these recommendations apply to all World Bank Group funded projects. 5

12 4.5 DISTINCTION BETWEEN SABS, NCR AND WHO The maximum outdoor L Aeq of 55 dba during the day and 45 dba during night time recommended by the WHO correspond to the typical rating levels for ambient noise in an urban district referred to in Table 6 of SABS Certain terminology used in the Noise Control Regulations and in the SABS 0103 have similar sounding, but not equal, meanings. Thus, Noise Regulations: SABS 0103: Ambient sound level is similar to Residual noise Noise level is similar to Rating level of ambient noise The assessment of noise in terms of SABS 0103 is based on determining how many decibels the level of noise due to the activity under investigation exceeds, or would exceed, the acceptable level for the particular district and relating this to the probable community response for such excess. In contrast, the Noise Control Regulations specify a maximum allowable level of 65 dba on noise sensitive land adjacent to a road. Where the predicted noise level exceeds 65 dba, noise mitigation measures may need to be implemented to ensure that this level is not exceeded. However, the existing Noise Control Regulations ignore situations where the introduction of a new road into a rural or residential area may cause a significant increase in ambient level. Thus an increase from 45 or 50 dba, respectively, to 65 dba would impose a very high noise impact on hundreds of residents near to the new road. The significance of the impact would consequently be very high. It is considered important to note that the 65 dba legal limit specified in the Noise Control Regulations exceeds the maximum L Aeq of 55 dba recommended by the World Health Organisation by 10 db. 10 db is a significant difference in terms of subjective human response to sound. In general, the greatest noise impact of any development occurs where there has been no development initially. Thus, the impact of a new road with only little traffic is very much larger than the impact of even a substantial increase in traffic flow on an existing road. 6

13 5. STUDY APPROACH The investigation was conducted in accordance with the South African Bureau of Standards Code of Practice 0328 Methods for environmental noise impact assessments. The following procedure was followed: The existing Rating Level, L r, of sound was determined at selected locations in the study area in accordance with Section of the Code. The Rating Level of future noise due to road traffic on the proposed route passing through or near each identified noise sensitive area was estimated following procedures contained in Section of the Code. The estimated noise impact on each identified area was determined by calculating the difference between the estimated rating level of future ambient noise and the acceptable rating level in accordance with Section of the Code. The assessment of the estimated noise impact was established in accordance with Section 7.5 of the Code by determining the probable community response from Table 6 of SABS Code of Practice 0103 The measurement and rating of environmental noise with respect to annoyance and to speech communication ; in terms of the Noise Control Regulations of the Environment Conservation Act 73 of 1989 and in terms of world best practice. These are summarised in Section 4. The effect of mitigation measures was quantified for each identified noise sensitive area using procedures contained in SABS 0210 as specified by the NIA process in SABS The algorithms used to calculate the 18-hour L Aeq, the influence of noise barriers and the data used to determine the influence of porous asphalt road surfaces were derived from SABS The L Aeq values are validated up to a range of 300 metres from a road. The accuracy of the calculated L Aeq decreases for distances beyond 300 metres. In terms of SABS 0238 the impact of road traffic noise is to be assessed in accordance with Table 6 of SABS For the purpose of this investigation the intensity of a predicted noise impact is qualified as follows: Negligible Low Medium High Predicted L r does not exceed the acceptable or residual L r Predicted L r exceeds the acceptable, or residual, L r by between 0 & 5 db Predicted L r exceeds the acceptable, or residual, L r by between 5 & 10 db Predicted L r exceeds the acceptable, or residual, L r by more than 10 db The significance of a noise impact is dependent on the intensity of the impact together with the area of land affected by road traffic noise that is zoned for residential, recreational, or other noise sensitive use, whether presently occupied or not. The significance is also determined by the particular land use, such as educational. Thus, the significance of a medium intensity of noise impact on farmland with one residential dwelling is considered to be low to medium; whereas the significance of a medium intensity of noise impact on a single school is considered to be high. In all cases the duration is assumed to be long term 7

14 6. MITIGATION OF NOISE All noise problems contain three elements: the noise source(s), the sound propagation path and the receiver(s) of the noise. Sections 6.1 through 6.4 present a general discussion of noise mitigation alternatives. The effect of specific alternative mitigation measures is quantified for each identified noise sensitive area using procedures contained in SABS 0210 as specified by the NIA process in SABS The algorithms used to calculate the influence of noise barriers and the data used to determine the influence of porous asphalt road surfaces as applied in the investigation of each noise sensitive area in this report are derived from SABS The term porous asphalt appearing in the discussions of mitigation measures in this report refers to porous road surfaces such as open grade bitumen rubber contained in SABS In calculating the 18-hour L Aeq, or 18-hour L r, a constant correction of 3,5 db, irrespective of vehicle speed, is applied if the road surface is porous. This constant correction has been used in all predictions contained in this report. However, experience and published literature [1,3] has shown that this value is not constant. It is dependent on vehicle speed and is highly dependent on surface texture. Use of modern low-noise porous asphalt surfaces can result in a reduction of 5 db or more compared to smooth dense asphalt at freeway speeds. This should be borne in mind when considering the different noise mitigation alternatives. 6.1 ROAD SURFACE TEXTURE Tyre/road interaction noise accounts for over 90% of the total noise generated by light vehicular traffic [2]. The level of engine noise of modern cars exceeds tyre/road noise only during the brief period when a vehicle accelerates from rest or when negotiating a steep gradient. The greatest influence on the level of noise produced is due to the road surface texture and porosity. Compared to a smooth dense asphalt road surface, a reduction in sound level of between 3.5 db at 50 km/hr to 8 db at 120 km/hr can be achieved using TWINlay, a two-layer, porous, bitumen-rubber surface with the upper surface consisting of 2/8 cubical aggregate and a porosity in excess of 20% [1]. Experiments are presently being conducted on even quieter surfaces with sound level reductions approaching 10 db. The new surfaces are also designed to eliminate clogging of the pores that is a disadvantage of open graded, porous surfaces. The reduction of road noise using modern, low noise surfaces, such as TWINlay, is significantly greater than conventional porous road surfaces used to date in this country. On the other end of the scale, deep grooved cement concrete and 14mm chip seal surfaces, typically used on many road surfaces in South Africa, are the noisiest surfaces producing almost 10 db higher sound levels compared to the quietest surfaces [1]. The cost incentive of using chip seal surfaces must therefore be weighed against the high social cost of the noise impact on a community. Many of the road noise complaints received have been due to chip seal road surfaces and conventional surfaces containing large aggregates. It is strongly recommended that these surfaces not be used on roads 8

15 within 1 km of residential areas, offices, recreation and parkland, or other noise sensitive areas. 6.2 NOISE BARRIERS Noise barriers are often seen as a general palliative against noise from road traffic. However, their effectiveness is limited. Barriers are only effective against road traffic if their effective height is at least two meters and they are positioned close to the noise source. Effective height is the vertical distance between where the line-of-sight joining noise source and receiver intersects a barrier and the top of the barrier. This is illustrated in Figure 1. Figure 1a. illustrates that for a road in cut, the ground floor of the dwelling is in the acoustic shadow of the barrier thereby benefiting from the barrier. However, the barrier provides no attenuation to the upper floor because the top of the window is in line of sight of traffic on the furthest lane. Lines of sight Effective barrier height for ground floor window for furthest vehicle a. Road below level of receiver no noise reduction of furthest vehicle for upstairs Effective barrier height for upper floor window for furthest vehicle b. Road elevated above receiver noise reduction of both vehicles for upstairs Lines of sight Effective barrier height for ground floor window c. Road on same level as surrounding land - no noise reduction of furthest vehicle for upstairs FIGURE 1. The effective height of a noise barrier for a road located: a. Below, b. Above, and c. On the same level as the receiver Figure 1b. illustrates the benefit of raising a road above the height of the receiver. Here a relatively low wall at the edge of the elevated road screens both ground floor and upper 9

16 floor of the dwelling. The wall is normally closer to the road edge and hence closer to the noise sources compared to a road at level or in cut. Figure 1c. illustrates the limited effectiveness of the physical barrier height for a road at grade. This represents the least effective use of a noise barrier. However, in practice the angle of the sides of a cutting are often such that the top of the noise barrier is far removed from the noise sources thereby offsetting the benefits of a road in cut. Furthermore, sound diffracts, or spills, over the top of a barrier. Dwellings located further away from a barrier benefit increasingly more from the reduction of noise with increased separation distance from the road and less from the barrier. In addition, under certain meteorological conditions, sound propagating in the atmosphere bends down towards the earth as illustrated in Figure 2. This condition generally prevails during wind still evenings and for light winds blowing from source to receiver direction. The impact of road noise is greatest for dwellings flanking the road. Although less severe, the noise impact can still be significant for dwellings located several hundred metres from a busy road. Hence the roar of road traffic that can be heard on the outskirts of cities. FIGURE 2. Refraction of sound through the atmosphere reduces effectiveness of a barrier. Trees and shrubs provide no meaningful reduction of sound from road traffic noise. They do provide a benefit by reducing the visual distraction of passing traffic. 6.3 SOUND INSULATION OF DWELLING FACADES The installation of doubling glazing is often suggested as a noise mitigation option. Although more acceptable in colder climatic regions, this is less tenable in the warm South African climate where windows are traditionally left open. Doubling glazing would need to be accompanied by the installation of costly forced, fresh-air ventilation systems with appropriate noise attenuation. This would not resolve the problem of noise intruding into private gardens and outdoor educational spaces of the effected properties. This intrusion of noise would impinge on the constitutional rights of owners and tenants of property to enjoyment/use of that property up to the property boundary, whether indoors or outdoors, with reasonable peace and quiet. 6.4 DISTANCE Doubling the distance between road noise source and a listener results in a 3 db reduction in noise level. Doubling the new distance results in a further 3 db reduction in 10

17 noise level. The use of distance, alone, in achieving acceptable noise levels is thus very costly in terms of land use. 6.5 SUMMARY Noise barriers are often essential to reduce noise levels in noise sensitive areas located adjacent to multi-lane freeways. However, the barrier height needs to be significantly greater than 3 metres to benefit upper storeys of nearest dwellings. The effectiveness of barriers is significantly reduced, if not negated, in hilly terrain if the road passes below the noise sensitive areas. The effectiveness of noise barriers decreases with increasing distance of the barrier from either the source or the receiver of noise. Beyond several tens of metres the reduction of noise is increasingly due to the increased distance and less due to the barrier. The most effective means of reducing the spread of road traffic noise over large areas, including areas close to the road, is reducing the noise at source. Namely, by utilising special low-noise road surfaces such as TWINlay[1]. The cost benefit far exceeds that of noise barriers when considering the area of land impacted upon by road noise. Unfortunately, noise barriers may still be needed to screen the nearest noise sensitive areas from the road. A 3 db reduction in noise at source is equivalent to doubling the distance of the listener from the road. Modern, low-noise road surfaces reduce the noise at source by 6 db or more. This is equivalent to more than a fourfold increase in distance between road and listener. This could be doubled again should the results of latest research on low-noise road surfacing be successful. 7. NOISE SENSITIVE AREAS. In terms of the Environment Conservation Act, the following sections of the routes of the N1 and N2 were identified potentially causing a noise impact on adjacent land: The location of mainline toll plazas and ramp plazas. New interchanges The introduction of a new road through an area The proposed Somerset West bypass. Changes made to an existing road This includes: The widening and the introduction of a new traffic lane on the sections of the N1 between Durban Road and the Brighton Road (Kraaifontein) interchange; The widening and the introduction of a new traffic lane on the sections of the N2 between Vanguard Drive and the R300; Realignment of the N1 through the Hex River Poort. 11

18 8. NOISE IMPACT OF TOLL PLAZAS The prediction of noise emanating from toll plazas is not straightforward. The standard procedures used to predict the noise from free-flowing traffic on freeways are inadequate to predict the impact of noise from toll plazas. Procedures are proposed in this investigation for predicting the combined noise emanating from the different sources that is perceived at distances from a toll plaza. Section 8.1 characterises the different types of noise that might be produced at toll plazas arising out of investigations conducted at three toll plazas in the country. The predicted impact of noise from alternative mainline toll plaza locations on the N2 are considered in detail in Sections 11.2 through The information contained in those Sections is used to estimate the impact of noise in the vicinity of the proposed mainline toll plaza locations on the N1(refer to Sections 9.2 and 9.3). 8.1 CHARACTERISTCS OF NOISE EMANTING FROM TOLL PLAZAS Jongens Keet Associates (JKA) previously undertook studies of the conditions that produce noise at three toll plazas in the country. These are the Machado Toll Plaza and the Middelburg Toll Plaza in Gauteng and the Huguenot Tunnel Toll Plaza in the Western Cape. The Machado Plaza is located on a section of the N4 freeway immediately east but outside the developed area of Machadodorp. The Middelburg Plaza is located on a section of the N4 freeway immediately south but outside the developed area of Middelburg. The Huguenot Toll Plaza is located on the N1 at the foot of the Du Toit s Kloof Mountains, close to the town of Paarl. The area around all three toll plazas is farmland with no residential or other development in the area that would be sensitive to noise from the toll plazas other than housing provided for toll plaza personnel. The noise emanating from a toll plaza is associated with a mixture of several sound sources. The sources identified at one or more of the three toll plazas studied include: i) General traffic operation sounds under stop-start (interrupted flow) conditions as vehicles pass through the tollbooths. ii) These normal sounds are, however, interspersed with sporadic, very loud and more intrusive sounds from some vehicles, including: Vehicles with overly noisy engines and exhaust systems. Vehicles decelerating and accelerating excessively loudly. This includes respectively the squeal of brakes from some light- and heavy-duty vehicles as well as the sudden, loud, high frequency hiss of the air brakes on many heavy-duty vehicles, and the loud revving of engines by some vehicles prior to accelerating out of the toll plaza. Rattling of badly maintained vehicles and badly loaded freight. Vehicles hooting. Radios in some vehicles being played very loudly. 12

19 The noise produced by the tyres and suspension of a vehicle during interaction with the rumble strips on some approaches to the plaza. The instantaneous, high impulse sound levels render this noise particularly noticeable at night when the ambient noise level is low. Intermittent sounding of a siren at the weighbridge indicating an overload of a heavy duty vehicle. The one-hour L Aeq values measured in the vicinity of the plaza booths studied varied between 72 and 78 dba, depending on the number of vehicles per hour, percentage heavy-duty vehicles, the driving conditions of individual vehicles and the number of adjacent lanes operating. However, these slowly varying sound levels were frequently interspersed with short duration levels of sound often exceeding 100 dba. The noise in the vicinity of a toll plaza is characterized by two distinct types of noise: i. Noise that fluctuates relatively little and slowly in level (loudness) and frequency content (tone) over a period of several seconds or minutes due to the collective noise of vehicles passing through the toll plaza. ii. Sporadic, abrupt emission of noise from single events occurring infrequently resulting in brief but significant changes in level and/or frequency of the ambient noise. Examples of the latter noise sources are rumble strips, compressed air release, siren and squeal of brakes. The significance of this distinction is that the subjective response to noise by a human listener is determined not only by the level of the noise but to a greater extent on the variability of the level and frequency content of the noise with time. The more constant the noise, the more readily a human listener becomes accustomed to the noise and the less conscious the listener is of the noise. In contrast, the more rapidly the noise changes with time, the more the listener is aware of the noise and the greater the probability of the noise intruding on the activity of the listener, be it work or rest. The first type of noise produced at a toll plaza can be predicted with a medium to high level of confidence by applying the same procedures used for free-flowing freeway traffic contained in the South African Bureau of Standards Code of Practice 0210 for Calculating and predicting road traffic noise. Methods for predicting the erratic but brief occurrence of high levels of sound do not appear in the standard procedures for predicting noise. In this investigation, the noise level at a distance from impulsive types of noise produced at the tollbooths is determined by assuming hemi-spherical spreading of sound from point sources producing a brief maximum noise level of 100 dba. For minimal impact of the noise at a receiver location, the instantaneous level of sound must not exceed the typical or existing rating level, whichever is relevant, of ambient noise for the area by 10 db. It is understood that the Proponent is not considering the use of rumble strips at any of the toll plazas. For completeness of the investigation, the effect of this type of noise is included. The procedures adopted in this investigation for determining the impulse correction for noise emanating from rumble strips are derived from a separate JKA report [4]. 13

20 9. N1 FREEWAY This section commences with the expected impact of noise from proposed toll plaza locations. This is followed by the expected impact of proposed interchanges and proposed ramp plazas; and subsequently the proposed realignments on the N1 route, relative to existing ambient noise levels. The predicted ambient levels of noise from alternative mainline toll plaza locations on the N2 are considered in detail in Sections The information contained in that Section is used to estimate the expected impact of noise in the vicinity of the proposed mainline toll plaza locations on the N MAINLINE TOLL PLAZAS AT WESTERN END OF CONCESSION Kraaifontein west of the Brighton Road Interchange (Kraaifontein) This location would be within 10 metres of the nearest residences. Assessment: The noise impact would be considerably higher than that at Khayelitsha West. The intensity of impact is expected to be High with High significance. Recommendations: With a 5-metre high noise barrier shielding the tollbooth and forecourt, the intensity of noise impact is expected to range between Low and Medium with Medium significance. This location is not recommended Joostenbergvlakte west of Joostenbergvlakte Interchange This location is bounded by farmland with the nearest farm dwelling located 300 metres to the north of the proposed tollbooths. Assessment: The expected intensity of impact would be expected to be Low with Low significance. Recommendations: The recommended mitigation should be determined at the detailed design stage Joostenbergvlakte east of Joostenbergvlakte Interchange This location is bounded by farmland with no dwellings within 300 metres of the N1. Assessment: No impact Recommendations: None. 14

21 9.1.4 Assessment summary: Comparative assessment of the Kraaifontein, Joostenbergvlakte West and East proposed toll plaza locations relative to existing conditions; assuming no rumble strips. IMPACT LOCATION Kraaifontein Joostenbergvlakte West Joostenbergvlakte East CRITERIA No mitigation Mitigation No mitigation Mitigation No mitigation Mitigation Extent Local Local Local Local Local Phase Operation Operation Operation Operation Operation Duration Long term Long term Long term Long term Long term No mitigation Intensity High Low to Med. Low Very low Low required Probability High High Medium Medium Medium Significance High Medium Low Very low Low Status Negative Negative Negative Negative Negative Confidence Low Low Low Low Low 9.2 HEX RIVER POORT AND SANDHILLS TOLL PLAZAS According to the CTO Yearbook 2000 the traffic counts at station 109 between Worcester and De Doorns indicate a relatively constant daytime traffic flow through the Poort of 340 vehicles per hour with 14% heavy-duty traffic between 07:00 hrs and 18:00 hrs. This reduces to less than 40 vehicles per hour between midnight and 04:00 hrs. The day- and night-time 1-hr L Aeq would be approximately 60 and 48 dba, respectively, for dwellings located 50 metres from the road. For sporadic high noise levels emanating from vehicles at the toll booths not to exceed the night time L Aeq of 48 dba by 10 db the separation distance between toll booths and nearest dwellings would need to exceed 260 metres in the absence of noise mitigation (refer to Section 8.1) De Wet This proposed site is located approximately 100 metres from a winery with sparse residential developments to the east of the road and a farm residence located approximately 130 metres west of the road. Assessment: The intensity of impact on the nearest dwellings is expected to be Medium with a Medium significance for both western and eastern areas. Recommendations: Erection of a barrier along the edge of the toll plaza would not shield the eastern residences from noise emanating from the tollbooths as the residences would be in direct line-of-sight of the toll booths. A noise barrier in excess of 2 metres height would need to be erected perpendicular to the road close to the nearest residential boundary. A noise barrier in excess of 2 metres height would need to be erected along the western side of the toll plaza. The expected intensity of impact would be reduced at both locations to Low with Low significance Glen Heatlie This proposed location lies within the Hex River Poort close to labourers cottages. It is proposed to realign the road on fill to reduce the curvature of the S-bend while retaining the existing rail bridge. This would bring the toll plaza to within 20 metres of the cottages. 15

22 Assessment: The intensity of impact on the nearest dwellings is expected to be High with a High significance. Recommendations: Unless the residents of the cottages are to be relocated, a 3-metre high wall along the western edge of the toll plaza would be required with an expected reduction in the intensity of impact to Medium with Medium significance Glen Heatlie North No noise sensitive land is located near this proposed location. Assessment: No impact Recommendations: It is recommended that this be chosen as the preferred location. 16

23 9.2.4 Sandhills This proposed location, shown in Figure 3, is at the bottom of a long incline leading from the Hex River Poort approximately 300 metres from the nearest residential dwellings. This location is similar to that at the Huguenot Toll Plaza where high noise levels accompany excessive speeds of passenger vehicles followed by rapid braking. The location is flanked on the southern side by steep mountain slopes that would cause sound to reflect into the residential area and the farmlands in the Hex River Valley to the north. Night time ambient levels in the valley are very low - below 30 dba. The erratic high noise levels produced at the toll plaza and the noise of braking and subsequent acceleration of heavy-duty vehicles are likely to be intrusive to farm residences in the valley at night despite the large distances from the N1. Assessment: The intensity of impact on the nearest dwellings is expected to be High with High significance. Recommendations: Erection of a 3-metre high barrier extending at least 50 metres on either side of the tollbooths along the northern edge of the toll plaza is expected to reduce the intensity of impact to Medium with Medium significance. FIGURE 3 Sandhills, showing proposed mainline Toll Plaza location and the proposed alternative road realignments. 17

24 9.2.5 Assessment summary: Comparative assessment of the Glen Heatlie, Glen Heatlie North, De Wet and Sandhills proposed toll plaza locations relative to existing conditions; assuming no rumble strips. IMPACT LOCATION Glen Heatlie Glen Heatlie North De Wet CRITERIA No mitigation Mitigation No mitigation Mitigation No mitigation Mitigation Extent Local Local Local Local Local Phase Operation Operation Operation Operation Operation Duration Long term Long term Long term Long term Long term Intensity High Medium No impact No mitigation Medium Low Probability Probable Probable Probable required Probable Probable Significance High Medium No impact Medium Low Status Negative Negative Neutral Negative Negative Confidence Low Low Medium Low Low IMPACT LOCATION Sandhills CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity High Medium Probability Probable Probable Significance High Medium Status Negative Negative Confidence Low Low 18

25 9.3 N1 INTERCHANGES AND RAMP PLAZAS Durban Road Interchange. An additional lane on the Cape Town-bound on-ramp is to be added on the median side of the ramp. The land bounding the southern side of the ramp is zoned industrial. In terms of SABS 0103 the typical day time and night time rating levels for ambient noise are 70 dba and 60 dba, respectively. The Danie Uys Park bounds the southern side of the N1 where the ramp merges with the N1. The site contains an amphitheatre. Although SABS 0103 contains no typical rating levels for recreational areas such as parks, the existing impact of noise on the Park is considered to be high. Assessment: It is expected that there would be no impact due to the additional lane. Recommendations: No mitigation is required for the adjacent industrial land. At the time of rehabilitation of the N1 all existing roads should be resurfaced with low-noise porous asphalt. This would result in a positive impact on a large area of land adjoining the N1. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Phase Operation Duration Long term Intensity No impact No mitigation Probability Medium required Significance No impact Status Neutral Confidence High Okavango Road Interchange. The upgrade would bring the northbound Okavango Road very close to existing residential areas. All these residences would experience an increase in noise impact with the degree of impact increasing with increasing distance from the N1. Assessment: Intensity of impact is expected to range between Medium and High with Medium to High significance dependent on distance from the N1. Recommendations: It is recommended that the new road be surfaced with low-noise porous asphalt plus a noise barrier, 1½ metres above road level is to be constructed close to the new road edge. With mitigation the intensity of impact is expected to be Low with Low significance. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Medium to High Low Probability Probable Probable Significance Medium to High Low Status Negative Negative Confidence Medium Medium 19

26 9.3.3 Brighton Road Interchange (Kraaifontein). New east-facing on- and off-ramps would bring traffic closer to residences. Sections of Brighton Road and van Riebeeck Street would be brought close to existing residences with increased noise impact. Assessment: The ramps would provide a benefit by reducing the existing noise from the N1. However, it is expected that this would be offset by closer traffic on the ramps. The resultant intensity of impact on residences close to the ramps is expected to remain unchanged. The intensity of impact for existing residences adjacent to the new sections of Brighton Road and van Riebeeck Street is expected to be Medium with Medium significance. Recommendations: The new roads are to be surfaced with low-noise porous asphalt plus 2-metre high noise barriers are to be constructed close to the new road edges facing the residences. These mitigation measures are expected to result in a benefit to all nearby residences by reducing the existing level of noise from the N1 and reducing the total noise from existing and new intersecting roads. Upon mitigation the resultant status would therefore be positive. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Medium Low Probability Probable Probable Significance Medium Low Status Negative Positive Confidence Medium Medium Joostenbergvlakte Interchange Ramp Plaza The proposed ramp plaza would be located very close to residential land (smallholdings) to the north. Industrial land is located on the southern side of the ramp plazas. Assessment: The estimated impact of the off-ramp on residences to the north would be Medium to High with Medium Significance. With mitigation it is expected that the impact would reduce to low intensity and low significance. It is estimated that there would be no impact on the industrial land on the southern side. Recommendations: A 3-metre high noise barrier is to be located close to the northern edge of the off-ramp extending 50 metre on either side of the tollbooths. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Medium to High Low Probability Probable Probable Significance Medium Low Status Negative Negative Confidence Medium Medium 20

27 9.3.5 R304 (Stellenbosch) Interchange No noise sensitive land is located in the vicinity of the proposed interchange. Assessment: No noise impact Recommendations: None Huguenot Tunnel eastern Ramp Plaza No noise sensitive land is located in the vicinity of the proposed interchange. Assessment: No noise impact Recommendations: None Florence Interchange No noise sensitive land is located in the vicinity of the proposed interchange. Assessment: No noise impact Recommendations: None 21

28 9.3.8 Worcester West Interchange Redundancy of the existing road (R43) to the east of the Rainbow Chickens farm would reduce the existing noise impact from this road on the farmhouse. This would, however be offset by increased vehicle speeds on the N1 route unless speed can be effectively controlled. The impact on farm cottages close to the N1 would be negligible. However, if vehicle speeds on the N1 increase due to uninterrupted traffic flow, there would be a marginal increase in impact. Assessment: Increased vehicle speeds on the N1 would result in an expected impact of Low intensity and Low significance and Negative status. If vehicle speeds are strictly enforced the expected impact would be of Low intensity and Low significance but Positive status. Recommendations: Strict enforcement of traffic speeds on the N1 to 100 kph by means of permanent cameras. At the time of rehabilitation of the N1 it is recommended that the size of aggregates used not exceed 10 mm and that the new surface be smooth and well rolled. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Low Low Probability Probable Probable Significance Low Low Status Negative Positive Confidence Medium Medium Casino Interchange Redundancy of the southern access road would marginally reduce the noise due to interrupted traffic flow presently experienced at residences in Brandwacht. Assessment: The estimated intensity of impact on the farm and Brandwacht dwellings would be Low with a Low significance and Positive status provided vehicles speeds are kept to 100 kph. Recommendations: Strict enforcement of traffic speeds on the N1 to 100 kph by means of permanent cameras. At the time of rehabilitation of the N1 it is recommended that the size of aggregates used not exceed 10 mm and that the new surface be smooth and well rolled. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Low Low Probability Probable Probable Significance Low Low Status Positive Positive Confidence Medium Medium 22

29 Roux overpass. Elimination of existing controlled intersection would reduce the level of noise impact due to smoother traffic flow. This would, however be offset by increased traffic speeds on the N1 route unless speed can be effectively controlled. Assessment: The estimated intensity of impact would be Neutral to Low with Low significance provided traffic speeds on the N1 are strictly enforced. Recommendations: Strict enforcement of traffic speeds on the N1 to 100 kph by means of permanent cameras. At the time of rehabilitation of the N1 it is recommended that the size of aggregates used not exceed 10 mm and that the new surface be smooth and well rolled. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Neutral to Low Low Probability Probable Probable Significance Neutral to Low Low Status Negative Positive Confidence Medium Medium High Street Overpass. Elimination of existing controlled intersection would reduce the level of noise impact due to smoother traffic flow. This would, however be offset by increased traffic speeds on the N1 route unless speed can be effectively controlled. Assessment: The estimated intensity of impact would be Neutral to Low with Low significance provided traffic speeds on the N1 are strictly enforced. Recommendations: Strict enforcement of traffic speeds on the N1 to 100 kph by means of permanent cameras. A 1½ -metre high noise barrier located close to the elevated road leading onto the bridge would reduce the impact of existing noise from High Street and result in Low Intensity of impact with a Positive status. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Neutral to Low Low Probability Probable Probable Significance Neutral to Low Low Status Neutral Positive Confidence Medium Medium 23

30 Worcester East Interchange Several farm dwellings would be located close to the ramp and access roads. Portions of these would be in cut while other portions would be on fill. Once the Eastern Ring Road has been constructed, high traffic volumes are anticipated with an anticipated significant increase in ambient noise levels at the farm dwellings. Assessment: The estimated intensity of impact would be Medium to High with Medium significance. Recommendations: All new roads are to be surfaced with low-noise porous asphalt. Noise barriers would need to be erected on roads at grade and on fill on the northern side of the interchange. The height of the noise barriers would need to be determined at the detail design stage. With the implementation of mitigation measures the intensity of impact is estimated to be Low to Medium with Low significance. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Medium to High Low to Medium Probability Probable Probable Significance Medium Low Status Negative Negative Confidence Medium Medium Further consideration for the N1 through Worcester If, at the time of rehabilitation of the N1 passing through Worcester, the existing surface were to be replaced with low-noise, two-layer, porous, rubber-bitumen asphalt, the properties of this surface would permit vehicle speeds at 120 kph while reducing levels of noise on adjacent land below existing noise levels. A further benefit would be improved safety in wet weather. The good drainage surface would result in improved tyre traction and markedly improved visibility of road markings accompanying the absence of spray. 24

31 9.4 REALIGNMENT OF THE N1 WITHIN THE HEX RIVER POORT Northern Section - Sandhills It is proposed to increase the capacity of the N1 in the Hex River Poort close to Sandhills by the construction of an additional two-lane carriageway. Alternative X, Y and O are shown in Figure 3 in Section Assessment: Alternative X represents constructing a northbound lane on a viaduct west of the existing alignment around a hill and exposed to farmers in the Hex River Valley. This would significantly increase the noise levels in the Valley particularly from heavy-duty vehicles during the day. The expected intensity of impact for this alternative is High with High significance. Alternative Y represents constructing a box cut to the east of the existing alignment to accommodate a southbound carriageway. Alternative O represents widening of the existing box cut to accommodate the additional carriageway. Both of these alternatives would screen the Valley from road noise along the new alignments. It is expected that alternatives Y and O would both result in Negligible Impact. Recommendations: It is recommended that either of alternatives Y and O be given preference over alternative X. Assessment summary: ALTERNATIVE X Y and O IMPACT CRITERIA No mitigation No mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity High Negligible Probability Probable Probable Significance High Very Low Status Negative Neutral Confidence Medium Medium Central Section near Glen Heatlie North No noise sensitive land is located near this section of the route. Assessment: No impact Southern Section Glen Heatlie This location lies within the Hex River Poort close to labourers cottages. The existing road alignment forms an S-bend with the closest separation distance between road and nearest cottage being 50 metres. Two alternative alignments have been proposed. 25

32 Alternative A would realign the road on fill to reduce the curvature of the S-bend while retaining the existing rail bridge. This would bring the road to within 20 metres of the cottages. This would result in an increase in L Aeq of approximately 4 db at the nearest cottage. An additional factor is that mean traffic speeds are likely to increase. It is expected that the increase in L Aeq would be limited to approximately 1 db. It is expected that the relative impact due to the combined effects would be between Low and Medium intensity with Low to Medium significance. Alternative B would remove the S-bend resulting in a gentle curvature with a new roadover-rail bridge constructed further south. The distance to the nearest cottage would remain unchanged compared to the existing alignment but would bring the realigned road approximately 20 metres closer to the remaining cottages. This would result in an increase in L Aeq of approximately 1 db at most of the cottages. An additional factor is that mean traffic speeds are likely to increase. It is expected that the increase in L Aeq would be limited to approximately 1 db. It is expected that the relative intensity of impact due to the combined effects would be Low and of Low significance. Recommendations: The replacement of the existing road surface within 500 metres of the cottages with a lownoise, two-layer, porous asphalt surface is expected to offset the negative impact of either alternative and result in a Low intensity of impact with Low significance and Positive status in the case of Alternative B Assessment summary: ALTERNATIVE A B IMPACT CRITERIA No mitigation Mitigation No mitigation Mitigation Extent Local Local Local Local Phase Operation Operation Operation Operation Duration Long term Long term Long term Long term Intensity Low to Medium Neutral to low Low Low Probability Probable Probable Probable Probable Significance Low to Medium Neutral to low Low Low Status Negative Negative Negative Positive Confidence Medium Medium Medium Medium 26

33 10. WIDENING OF THE N1 BETWEEN DURBAN ROAD AND BRIGHTON ROAD (KRAAIFONTEIN) AND N2 BETWEEN VANGUARD DRIVE AND THE R300. The Proponent intends to widen the N1 between Durban Road and Brighton Road (Kraaifontein) and the N2 between Vanguard Drive and the R300 by increasing a lane on the median side of each carriageway. The potential impacts of noise of both of these sections of the respective routes need to be considered in terms of the Noise Control Regulations. The results of extensive noise measurements conducted at various locations along the N1 are recorded in Section They represent the results of noise for differing elevations between noise source and receiver. Due to the similarity of existing and anticipated future traffic flow conditions and the associated production of road noise, these sections of the N1 and N2 routes are considered together in this Section. The assessments of the noise from existing and future traffic on the N1 and N2 are considered in Sections 10.1 and 10.2, respectively. From the CTO Yearbook 2000 the average mid-morning traffic flow at Counting Station 610, Old Oak Road on a Tuesday is a total of 3200 vehicles per hour. At Counting Station 706, Swartklip, just west of the R300, the corresponding traffic flow is 2800 vehicles per hour. These stations are both on the sections of the N1 and N2, respectively, for which an additional lane in each direction is proposed. The mean traffic speed on each of these sections is estimated to be approximately the same. The difference in traffic volumes between the two sections accounts for a difference of 0,6 db in noise level produced at a given distance for the same traffic speed. This difference is negligible with respect to the subjective human response to noise. It has therefore been assumed that the existing impact of noise due to traffic on the N2 is the same as that for the N1 for the same separation distance and relative elevations. The discussion regarding assessment of the noise from existing and future traffic considered, respectively, in Sections 10.1 and 10.2 for the N1 between Durban Road and Brighton Road therefore also applies to the section on the N2 between Vanguard Drive and the R300. The only difference is that the topography adjacent to the section of the N2 is for the most part level whereas this is not the case for the section along the N1. These differences have been taken into consideration MEASUREMENT AND ASSESSMENT OF EXISTING NOISE IMPACT Ambient noise levels on land adjacent to the N1 Sound measurements were conducted during weekdays along several locations along the N1. The locations were considered representative of different source/receiver locations on the N1 and the N2. Simultaneous traffic counts were recorded during each sound measurement. The mean speed was estimated by driving along this section of the N1 at the same speed as surrounding traffic immediately after completion of the sound measurements. The microphone of the sound level meter was 1,4 metres above local ground level. The following 1-hr L Aeq were recorded: 27

34 Tygerberg - Parc du Cap site 1-hr L Aeq Means Speed: Distance from road edge: Location: Measurement time: Traffic flow: 68 dba. 125 kph 150 metres Sloping ground overlooking N1 near the ends of the ramps on the Cape Town side of the Durban Road interchange 16:50 to 17:50 hrs vehicles on westbound carriageway; 5230 vehicles on eastbound carriageway; 3% heavy-duty traffic From these measurements it was calculated that the 1-hr L Aeq at residential properties in Oakdale suburb, 40 metres north of this section of the N1, was 74 dba Oakdale c/o Barnard and Springfield Roads 1-hr L Aeq 68 dba. Means Speed: 140 kph (including all heavy-duty vehicles) Distance from road edge: 35 metres Location: at boundary of nearest residential property below the level of the N1 with the top of a single storey window being approximately level with the road surface. The eastbound carriageway was partially obscured from the measurement location. Measurement time: 14:30 to 15:30 hrs Traffic flow: 2854 vehicles on westbound carriageway; 11% heavy-duty traffic Plattekloof - Landdros Protea Hotel. 1-hr L Aeq 80 dba. Means Speed: 110 kph (including all heavy-duty vehicles) Distance from road edge: 30 metres Location: on the lawn in line with the facades of the hotel buildings overlooking the N1 in direct line-of-sight of seven traffic lanes. Measurement time: 16:45 to 17:45 hrs Traffic flow: 5180 total; 4,2% heavy-duty traffic Paarl Several sound measurements were conducted between 10:00 hrs and 13:00 hrs at residential boundaries closest to the N1. No estimation of vehicle speeds was made. The N1 is in cut and is partially obscured from residents fronting New Vlei Road. The Pieter Hugo Road site was in line-of-sight of the N1. Location Vehicles per hour % heavy-duty 1-hr L Aeq, dba c/o Vlei & New Vlei 28m c/o Tabak & New Vlei 18m c/o Steward & New Vlei 19m Pieter Hugo 21m

35 For each location the measured noise levels were compared with calculated 1-hour L Aeq in accordance with SABS 0210, for the same traffic volume and mean speed and relative locations. In each case the calculated noise level was within 1 db of the measured level. This represents a close correlation thereby providing confidence in the prediction of road traffic noise in accordance with procedures contained in SABS Assessment: The measurements indicated that the existing ambient daytime levels of noise at residences adjoining the N1 equalled or exceeded the 65 dba limit contained in the Noise Control Regulations. In terms of SABS 0103 and in terms of World Best Practice the level of ambient noise at many of the residences along the N1 is already unacceptably high with a high social cost presently being borne by the affected communities. The existing impact of noise due to traffic on the N2 is assumed to be the same as that for the N1 for the same separation distance and relative elevation. The results of the measurements indicate that all residential properties adjacent to the N1 between Durban Road and Brighton Road (Kraaifontein) and the closest residences adjacent to the N2 between Vanguard Drive and the R300 are presently exposed to very high levels of ambient noise with associated High intensity of noise impact in terms of the SABS 0103 and unacceptably high in terms of World Best Practice. In all instances the 18-hour L Aeq determined from the measured values equal or exceed the legal limit of 65 dba contained in the Noise Control Regulations NOISE IMPACT OF ROAD WIDENING. The addition of an extra lane in each direction between Durban Road and Brighton Road on the N1 and between Vanguard Drive and the R300 on the N2 would initially cause an insignificant increase in existing ambient noise level. However, due to the increased capacity it is anticipated that during the concession period there would be a measurable increase in ambient noise level of up to 3 db. In accordance with Section 3 (d) of the Noise Control Regulations noise control measures would need to be considered. Assessment: The relative intensity of noise impact due to the proposed extra lanes is expected to be Low with Low significance. However, the actual levels of ambient noise are and would remain unacceptably high in terms of SABS 0103 and in terms of World Best Practice in the absence of noise mitigation measures. Strictly in accordance with the Regulations, noise mitigation measures would need to be implemented along these sections of the two routes in order to reduce the noise level on adjacent land to 65 dba from existing levels that are significantly higher than this value. In terms of National Regulations and National and International recommendations there is no debate regarding the need to reduce the existing high levels of noise along the two routes. The debate centres around who should bear the substantial cost of noise mitigation measures required to correct a situation that has arisen out of previous planning decisions. Although the debate is considered to be outside the scope of this study, it is pertinent to note that the existing situation is not unique to this country. It is considered prudent for planners and decision makers in this country to consider the history of noise control in 29

36 other countries. The United States, Europe and Eastern countries have in the past all been faced with the same road noise problems associated with increased traffic density. This resulted initially in a fire fighting response of erecting high, unsightly noise barriers (up to 10 metres in height) coupled with a growing awareness of the need to control and reduce levels of road traffic noise. This was followed by legislation to control and reduce road traffic noise accompanied subsequently by national noise control policies that included procedures for a holistic approach to all forms of noise to be adopted by planners, decision makers and local and national government. Most importantly, in most instances, mechanisms have been put into place for the cost of noise mitigation to be shared between road builder/developer and the broader community. Recommendations: It is strongly recommended that the new lanes on the N1 and the N2 freeways be surfaced with low-noise, two-layer, porous asphalt and that existing sections of both freeways be resurfaced with low-noise, two-layer, porous asphalt when rehabilitation is required. These mitigations measures will, however, not bring the noise levels down sufficiently to comply with the Noise Control Regulations. With due regard to the previous paragraphs of this Section, it is further recommended that that the relevant authorities (NRA and local authorities) should address the fact that, in addition, noise barriers will need to be erected along both sections of the routes to comply with the Noise Control Regulations. Assessment summary: Relative impact of the proposed road widening along the N1 and the N2. The impact of mitigation in this summary only considers the use of low-noise, two-layer, porous asphalt. IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Low Medium Probability Probable Probable Significance Low Medium Status Negative Positive Confidence Medium Medium 30

37 11. N2 TOLL ROUTE Section 11.1 explains the contents of the tables used in Sections 11.2 through 11.4 to predict the rating levels of noise, L r, and the expected relative impact of noise at the nearest noise sensitive sites to proposed toll plaza locations on the N1 and N2 routes. Section 11.5 considers the relative impact of proposed interchanges and of ramp plazas. Section 11.6 considers the proposed Somerset West By-Pass between Helderzicht and Firlands. Section 11.7 considers, in detail alternative mitigation measures to reduce the noise from the proposed By-Pass EXPLANATION OF TABLE HEADINGS AND CONTENTS The description of each of the proposed toll plaza locations on the N2 contained in Sections 11.2 through 11.4 are accompanied by one or more Tables containing the results of calculations predicting the noise levels at the nearest noise sensitive area for various mitigation conditions in terms of the Rating Level of Sound, L r, determined over several reference time periods. The L r is defined in SABS 0103 as the calculated L Aeq over the respective time period to which is added a correction due to impulsive noise (refer to Section 4.1.1). Assessment of road traffic noise in terms of the Noise Control Regulations applicable to the Province of the Western Cape is based on the value of the 18-hour L Aeq without consideration of any impulse correction, as this type of noise is unusual and absent in normal free-flowing road traffic. In this study, an applicable impulse correction [4] is added to the 18-hour L Aeq and to the L Aeq for each reference time interval when considering impulsive noise emanating from road traffic moving over rumble strips on the approach to the tollbooths. Reference time period The reference time periods in the first three rows of each Table are the night time, daytime and evening reference time periods defined in SABS The L r in the last row is the 18- hour L Aeq to which an impulse correction is added, if applicable. Existing traffic conditions The L r values are those for existing free-flowing traffic. The L r values equal the L Aeq values in the absence of any impulsive type of noise. In certain tables the influence of a porous asphalt road surface is included. With toll plaza The mean speed of traffic within 280 metres of the tollbooths is assumed to be 80 kph. The mean speed of traffic beyond 280 metres of the tollbooths is assumed to be 120 kph unless otherwise indicated. No barriers The L r values are those predicted in the presence of a toll plaza without noise barriers. 3m (or 5m) barrier at plaza A 3 or 5 metre high barrier, assumed to be located 20 metres from the nearest road edge, extending 280 metres on either side of the tollbooths. Calculations indicated that 3 metres was the minimum height for a barrier to provide a significant reduction in noise level. 31

38 Instantaneous level This is the maximum instantaneous A-weighted sound level at the receiver location due to the impulsive sources of noise emanating from the vicinity of the tollbooths described in Section 10.1 but excluding rumble strips. Rumble strips The L r values are the calculated L Aeq to which are added an impulse correction due to noise emanating from rumble strips upon a 280-metre length of the road approaching the tollbooths. This is the length of the approach road containing rumble strips at the Huguenot Tunnel Toll Plaza [4]. 32

39 11.2 N2 KHAYELITSHA MAINLINE TOLL PLAZA LOCATIONS Three alternative locations for a toll plaza have been proposed near Khayelitsha: Khayelitsha West situated east of the R300 interchange; Khayelitsha Central situated between the M44 and M32 (Spine Road) interchange; Khayelitsha East situated approximately midway between the M32 and R310 (Baden Powell) interchanges. The predicted noise levels from road traffic on land adjacent to the toll plazas along this section of the N2 were obtained from hourly traffic flow counts at Counting Station 710 recorded on page 224 of the South African National Roads Agency Ltd Comprehensive Traffic Observations (CTO) Yearbook Typical flow for a Tuesday are reproduced in Figure 4 and summarised in the accompanying Table. The mean speed of passenger vehicles was taken as 120 kph on the freeway beyond 280 metres from the tollbooths. Within the 280-metre approach road to the tollbooths the mean speed was taken as 80 kph. These speeds were derived from the investigation conducted at the Huguenot Toll Plaza [4]. Westbound Eastbound Total Hr CT SW Hr CT SW CT: Traffic flow 100 in Cape Town direction SW: Traffic flow 100 in Somerset West direction FIGURE 4. Hourly traffic flow at Counting Station Number 710, Khayelitsha, N2. 33

40 Khayelitsha West Figure 5 shows the proposed Khayelitsha West toll plaza location and road reserve outlined in yellow. The proposed toll plaza location is flanked by formal and informal settlements on both sides of the N2. The nearest dwellings to the north are situated approximately 75 metres from the N2 and the distance to those on the southern side of the carriageway approaching the tollbooths is 120 metres. Beyond the toll plaza, informal settlements are located within 40 metre of the westbound carriageway. 30 m 56 m m 75 m 120 m FIGURE 5. Proposed site of Khayelitsha West toll plaza. Table 1a and 1b record the calculated L r in dba for different noise mitigation conditions over different reference time periods at the nearest dwellings lying 120 metres to the south of the N2. The L r exceeding 64 dba are indicated in bold red type. 34

41 TABLE 1a. Reference time L r and instantaneous sound levels for different mitigation conditions at 120 metres. Dense asphalt. Existing With toll plaza Reference time period traffic Instantaneous level Rumble strips, L r conditions No Barrier 3m barrier No barrier 3m barrier 5m barrier 6-hr nighttime L r hr daytime L r hr evening L r hour L r TABLE 1b. Reference time L r and instantaneous sound levels for different mitigation conditions at 120 metres. Porous asphalt. Existing With toll plaza Reference time period traffic Instantaneous level Rumble strips, L r conditions No Barrier 3m barrier No barrier 3m barrier 5m barrier 6-hr nighttime L r hr daytime L r hr evening L r hour L r Table 2a and 2b record the calculated L r in dba for different noise mitigation conditions over different reference time periods at the nearest dwellings lying 75 metres to the north of the N2. The L r exceeding 64 dba are indicated in bold red type. TABLE 2a. Reference time L r and instantaneous sound levels for different mitigation conditions at 75 metres. Dense asphalt. Existing With toll plaza Reference time period traffic Instantaneous level Rumble strips, L r conditions No Barrier 3m barrier No barrier 3m barrier 5m barrier 6-hr nighttime L r hr daytime L r hr evening L r hour L r TABLE 2b. Reference time L r and instantaneous sound levels for different mitigation conditions at 75 metres. Porous asphalt. Existing With toll plaza Reference time period traffic Instantaneous level Rumble strips, L r conditions No Barrier 3m barrier No barrier 3m barrier 5m barrier 6-hr nighttime L r hr daytime L r hr evening L r hour L r

42 Khayelitsha Central Figure 6 shows the proposed Khayelitsha Central toll plaza location and road reserve outlined in yellow. The nearest informal settlements are situated approximately 240 metres to the south of the N2. No dwellings are located immediately to the north of the N m 240 m 60 m FIGURE 6. Proposed alternative site of Khayelitsha Central toll plaza. Table 3 records the calculated L r in dba for different noise mitigation conditions over different reference time periods at the nearest dwellings lying 240 metres to the south of the N2. The L r exceeding 64 dba are indicated in bold red type. TABLE 3. Reference time L r and instantaneous sound levels for different mitigation conditions at 240 metres. Dense asphalt. Existing With toll plaza Reference time period traffic Instantaneous level Rumble strips, L r conditions No Barrier 3m barrier No barrier 3m barrier 5m barrier 6-hr nighttime L r hr daytime L r hr evening L r hour L r

43 Khayelitsha East Figure 7 shows the proposed Khayelitsha East toll plaza location and road reserve outlined in yellow. The nearest informal settlements are situated approximately 290 metres to the south of the N2. No dwellings are located immediately to the north of the N m 280 m 25 m 317 m 290 m FIGURE 7. Proposed alternative site of Khayelitsha East toll plaza. Table 4a and 4b record the calculated L r in dba for different noise mitigation conditions over different reference time periods at the nearest dwellings lying 290 metres to the south of the N2. The L r exceeding 64 dba are indicated in bold red type. 37

44 TABLE 4a. Reference time L r and instantaneous sound levels for different mitigation conditions at 290 metres. Dense asphalt. Existing With toll plaza Reference time period traffic Instantaneous level Rumble strips, L r conditions No Barrier 3m barrier No barrier 3m barrier 5m barrier 6-hr nighttime L r hr daytime L r hr evening L r hour L r TABLE 4b. Reference time L r and instantaneous sound levels for different mitigation conditions at 290 metres. Porous asphalt. Existing With toll plaza Reference time period traffic Instantaneous level Rumble strips, L r conditions No Barrier 3m barrier No barrier 3m barrier 5m barrier 6-hr nighttime L r hr daytime L r hr evening L r hour L r A study of the results of the calculations contained in Tables 1 through 4 indicate the following: 1. The present 18-hour L Aeq at all of the dwellings located closest to the N2 freeway exceed the 65 dba limit contained in the Noise Control Regulations or are within 1 db of this limit for existing traffic conditions. In terms of SABS 0328 the noise impact of existing traffic is of high intensity. 2. The calculations predict that Khayelitsha East is the only location, in the absence of rumble strips, where no mitigation measures would be needed to comply with the Noise Control Regulations 65 dba 18-hour L Aeq limit. However, in terms of SABS 0328 the actual intensity of noise impact would be high even with a 3 metre high barrier plus the use of porous asphalt at and beyond the toll plaza. 3. The use of rumble strips would present a noise impact of high intensity in the vicinity of Khayelitsha West and Central, even with the implementation of extensive noise mitigation measures. In the vicinity of Khayelitsha East the intensity would be high for both a 3 metre and 5 metre high barrier. 4. In terms of SABS 0328 the intensity of noise impact in the vicinity of all three locations would still be high due to noise emanating from the unaltered sections of the N2 away from the toll plazas. The intensity and significance of impact would only be reduced if mitigation measures, in the form of noise barriers as well as a low noise road surface, were implemented along the entire route through Khayelitsha (refer to Section 10.2). In assessing the noise impact of any of the proposed toll plaza locations it needs to be borne in mind that, due to the volume of existing traffic flow past Khayelitsha, with a mean speed of the order of 120 kph, the intensity of the noise impact is already high up to distances of 290 metres from the freeway (refer to the first column of Tables 1 through 4). The noise impact is assessed by comparing the predicted noise from the toll plaza combined with freeway traffic noise with the acceptable level for the particular district as described in Section 5. The placing of a toll plaza along this stretch of the freeway has the effect of reducing the mean speed of vehicles within ¼ km of the plaza associated with a decrease in noise 38

45 level. This is, however, offset by the intrusive effects of unpredictable, sporadic, impulse types of noise emanating from the immediate vicinity of the tollbooths. With increased distance from the toll plaza location the relative contribution of noise from the freeway increases. Beyond approximately 300 metres the freeway noise is dominant. At all three toll plaza locations rumble strips within 290 metres of noise sensitive land would cause a very high noise impact, even with a 5 metre high barrier extending the full length of road covered with rumble strips. The results support the Proponent s decision not to implement rumble strips Assessment summary: Comparative assessment of the relative effect of Khayelitsha West, Central and East toll plaza locations assuming no rumble strips. IMPACT LOCATION Khayelitsha West Khayelitsha Central Khayelitsha East CRITERIA No mitigation Mitigation No mitigation Mitigation No mitigation Mitigation Extent Local Local Local Local Local Local Phase Operation Operation Operation Operation Operation Operation Duration Long term Long term Long term Long term Long term Long term Intensity High Low Low Low Low Low Probability High High High High High High Significance High Low Low Low Low Low Status Negative Negative Negative Positive Negative Positive Confidence Medium Medium Medium Medium Medium Medium Recommendations: It is recommended that, of the three locations, only Khayelitsha Central and East be considered. In view of the expected Low intensity of the relative impact mitigation measures would probably not be required. With regard to the high levels of existing noise, reference is made to Section 10.2 relating to the need to reduce the existing levels of noise along this section of the route. 39

46 11.3 FIRLANDS WEST AND FIRLANDS MAINLINE TOLL PLAZA LOCATIONS Figure 8 shows the proposed Firlands West and Firlands mainline toll plaza locations and the proposed Firlands Interchange. Ramp plazas are proposed on either the western or eastern ramps depending on the location of the mainline toll plaza. 270 Firlands Toll Plaza Firlands Interchange FIGURE 8. Proposed location of Firlands mainline plaza on realigned N2 on realigned N Firlands West Toll Plaza Several farm dwellings would be located within 100 metres, north of the tollbooths of this alternative Toll Plaza location. Assessment: In the absence of a toll plaza it is expected that the impact due to noise emanating solely from the new N2 on all the residences in this area would result in a High intensity with a High significance (refer to Section 10). The addition of a toll plaza would result in instantaneous sound levels at residential dwellings located within 100 metres from the tollbooths being 6 db higher than the ambient levels during night time. The expected intensity of impact relative to the new road alignment would therefore be Medium with a Medium significance. It is expected that a 3 metre high barrier extending 50 metres on either side of the tollbooths would reduce the impact to Low with Low significance. The combined impact of a new road plus a toll plaza at this proposed location is expected to be High. Recommendations: It is recommended that this location is not the preferred location. 40

47 Firlands Toll Plaza The nearest residential development lies approximately 270 metres to the north of the toll plaza. The predicted noise levels from road traffic on land adjoining the toll plaza along this section of the N2 were obtained from hourly traffic flow counts at Counting Station 3016, Somerset West recorded on page 227 of the CTO Yearbook Typical flow for a Tuesday are reproduced in Figure 9 and summarised in the accompanying Table. The mean speed of passenger vehicles was taken as 120 kph on the freeway beyond 280 metres from the tollbooths. Within the 280-metre approach road to the tollbooths the mean speed was taken as 80 kph. These speeds were derived from the investigation conducted at the Huguenot Toll Plaza. Table 5 records the calculated L r and instantaneous sound levels in dba for different noise mitigation conditions over different reference time periods at the nearest dwellings lying 270 metres to the north of the N2. The levels exceeding 64 dba are indicated in bold red type. Westbound Eastbound Total Hr CT SW Hr CT SW CT: Traffic flow 100 in Cape Town direction SW: Traffic flow 100 in Somerset West direction FIGURE 9. Hourly Traffic flow at Counting Station 3016, Somerset West. 41

48 TABLE 5. Reference time L r and instantaneous sound levels for different mitigation conditions at 270 metres. Dense asphalt. Realigned With toll plaza Reference time period N2 Instantaneous level Rumble strips, L r L r No Barrier 3m barrier No barrier 3m barrier 5m barrier 6-hr nighttime L r hr daytime L r hr evening L r hour L r Assessment: Realignment of the N2 would benefit the new residential development by increasing the separation distance from approximately 200 metres to 350 metres. For the same traffic flow conditions this would result in a 2 db reduction in L Aeq. The 18-hour L r is expected to be below the NCR 65 dba limit. However, in terms of SABS 0328 the impact due to the realigned N2 would be medium to high. It is expected that the relative intensity of impact of a toll plaza at this location, without rumble strips, would be Medium. Recommendations: It is recommended that a 3 metre high barrier be erected extending 50 metres on either side of the tollbooths in order not to increase the level of impact Assessment summary: Comparative assessment of the relative impacts of Firlands West and Firlands toll plaza sites assuming no rumble strips. IMPACT LOCATION Firlands West Firlands CRITERIA No mitigation With mitigation No mitigation With mitigation Extent local local local local Period Operation Operation Operation Operation Duration Long term Long term Long term Long term Intensity Medium Low Medium No impact Probability High High High High Significance Medium Low Medium Low Status Negative Negative Negative Neutral Confidence Medium Medium Medium Medium 42

49 11.4 N2 HOUWHOEK PASS AND BOT RIVER MAINLINE TOLL PLAZA LOCATIONS Houwhoek Pass The proposed location of the mainline toll plaza at Houwhoek Pass is shown in Figure 10. Houwhoek Houwhoek Toll Plaza FIGURE 10. Proposed sites of the Houwhoek Pass mainline Toll Plaza. The proposed location is far removed from any noise sensitive land. Assessment: It is expected that there would be no impact. 43

50 Bot River The proposed location of the mainline toll plaza, to the south of Bot River is shown in Figure 11. The distance between the edge of the toll plaza and the nearest residences is approximately 180 metres. Bot River Plaza Ramp plaza FIGURE 11. Proposed sites of the Bot River mainline Toll Plaza and Ramp Plaza. No hourly traffic flow counts were available in the vicinity of Bot River. Counting Station 080 between Sir Lowry s Pass and the Grabouw turn-off was the nearest counting station for which hourly traffic flow data could be obtained. This is recorded on page 232 of the CTO Yearbook The published average daily traffic flow is vehicles including 9,6% heavy-duty vehicles. Figure 2c of the Final Scoping Report records an average daily traffic flow of vehicles including 7% heavy-duty vehicles at this location. This is 97% of the CTO value. At the Bot River mainline plaza the values shown in Figure 2c of the Final Scoping Report are 4500 vehicles including 9% heavy-duty vehicles; thus approximately 35% of the average daily traffic flow at Grabouw. The predicted noise levels from road traffic on land flanking the Bot River mainline plaza were calculated using 34% of the hourly traffic flow counts for a Tuesday at Counting Station 080 at Grabouw. Typical hourly traffic flow are reproduced in Figure 12 and the adjusted values are summarised in the accompanying Table. The mean speed of passenger vehicles was taken as 100 kph on the N2 beyond 280 metres from the tollbooths. Within the 280-metre approach road to the tollbooths the mean speed was taken as 80 kph. 44

51 Westbound Eastbound Total Hr CT CA Hr CT CA CT: Traffic flow 100 in Cape Town direction CA: Traffic flow 100 in Caledon direction FIGURE 12. Hourly traffic flow at Counting Station 080, Grabouw with tabulated values reflecting a 34% adjustment for flow at Bot River - see text. TABLE 6. Reference time L r and instantaneous sound levels for different mitigation conditions at 180 metres. Dense asphalt. Existing With toll plaza Reference time period traffic Instantaneous level Rumble strips, L r conditions No Barrier 3m barrier No barrier 3m barrier 5m barrier 6-hr nighttime L r Not required 12-hr daytime L r Not required 6-hr evening L r Not required 18-hour L r Not required Assessment: For all scenarios it is expected that the 18-hour L r would be below the Noise Control Regulations 65 dba limit. In terms of the Regulations no noise mitigation measures would be required. In terms of SABS 0328 it is expected that the intensity of impact would be medium without mitigation and low to medium with mitigation. The significance levels are considered to be medium and low, respectively. 45

52 Assessment summary: Comparative assessment of the relative impacts of Houwhoek Pass and Bot River mainline toll plaza sites assuming no rumble strips. IMPACT LOCATION Houwhoek Pass Bot River CRITERIA No mitigation With mitigation No mitigation With mitigation Extent local local local local Period Operation Operation Operation Operation Duration Permanent Permanent Permanent Permanent Intensity No impact No impact Medium Low to medium Probability High High High High Significance Very low Very low Medium Low Status No impact No impact Negative Negative Confidence Medium Medium Medium Medium Recommendations: It is recommended that, of the two locations, the Houwhoek Pass location be considered, as there would be no associated impact. If the Bot River location is chosen, it is recommended that a 3 metre high barrier be erected on the northern side extending 50 metres on either side of the tollbooths. 46

53 11.5 N2 INTERCHANGES AND RAMP PLAZAS Firlands Interchange and Ramp Plazas The proposed interchange is shown in Figure 8. There are few residences in the area except to the southeast of the proposed interchange. It is expected that the major noise impact on the residences would be due to the proposed new N2 bypass. The intersection would be on a major feeder to and from Gordons Bay and the coast road. It is expected that there would be high traffic volumes on the west-facing ramps, particularly during weekends. It is proposed to locate ramp plazas on the east- or west-facing ramps. Assessment: The elevated ramps would provide partial screening of residences located close to the ramp from the N2 route. This would result in a reduction of noise from the screened portion of the N2. However, it is expected that this would be offset by the noise from accelerating vehicles on the westbound ramp. Thus, assessed in terms of the new N2 bypass, it is expected that the intensity of impact of the interchange on the closest residences would be Low. It is expected that the impact of the ramp plazas will be insignificant compared to the noise generated by traffic on the ramps. Recommendations: Notwithstanding the Low intensity of impact, when considering the proposed interchange as part of the proposed N2 bypass, it is recommended that a 1½ -metre high wall be erected along the south-eastern edge of the westbound ramp to reduce the level of particularly low-frequency noise emanating from vehicles accelerating on the ramp. Assessment summary: Assessment of the interchange relative to the presence of the realigned N2. IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Low Low Probability Probable Probable Significance Low Low Status Neutral Positive Confidence Medium Medium 47

54 Pineview A squatter settlement on the north-eastern side of the intersection extends almost up to the edge of the road. Assessment: Smoother traffic flow, due to removal of existing intersection, would reduce noise impact on surrounding land. The elevated east-facing ramp would provide partial screening of the squatter community located close to the ramp from the N2 route resulting in further reduction in exposure to noise from the N2 route. Although traffic on the ramp would be brought closer to the settlement it is expected that the intensity of impact due to the interchange would be Low. Screening the noise of traffic on the east-facing ramp is expected to provide a positive impact. Recommendations: It is recommended that a one metre high wall be erected along the east-facing ramp to reduce the level of noise emanating from vehicles on the ramp. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Local Phase Operation Operation Duration Long term Long term Intensity Low Low Probability Probable Probable Significance Low Low Status Neutral to positive Positive Confidence Medium Medium Grabouw West The Orchards farm stall is the only noise sensitive area located close to the intersection. Assessment: Smoother traffic flow due to removal of the existing intersection would reduce noise impact on surrounding land. The elevated east-facing access ramp would provide partial screening of the farm stall from the N2 route resulting in further reduction in exposure to noise from the N2 route. The traffic flow on the eastbound ramp is expected to be low with little to no increase in noise. It is therefore expected that the interchange would have a positive impact. Recommendations: None Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Phase Operation Duration Long term Intensity Low No mitigation Probability Probable required Significance Low Status Positive Confidence Medium 48

55 Grabouw East Road traffic on the bridge is expected to be low. Both proposed alternatives are sufficiently far removed from residential dwellings and the farm stall not to cause any significant noise impact. Alternative 1, being further removed from the nearest dwelling would impose least noise impact. Assessment: It is expected that the intensity of impact of both alternatives would be low with a very low significance. Recommendations: Due to the larger separation distance with noise sensitive areas it is recommended that alternative 1 be considered. Assessment summary: IMPACT CRITERIA No mitigation Mitigation Extent Local Phase Operation Duration Long term Intensity Low No mitigation Probability Probable required Significance Very Low Status Negative Confidence Medium Kromco No noise sensitive land is located close to the proposed alternatives. Assessment: No noise impact is expected. Recommendations: None 49

56 Houwhoek Interchange. The N2 and the existing intersection are located near several residences of Houwhoek Village. The existing rough road surface is the cause of unnecessarily high levels of existing noise being experienced in Houwhoek Village and the Houwhoek farmstall. Two of initially three proposals are presently being considered: Alternative 1 proposes removal of an existing intersection opposite the farm stall providing access to the farm stall and Houwhoek Village and a second east of this, linking with Houwteq Road, and constructing an underpass linking the latter with the Village and via a ramp linking with the N2 on the northern side. Alternative 2 considers locating the underpass 1 km east of the first proposal and relocating the farm stall to this location. Assessment: The estimated intensity of impact of the interchange is considered to be negligible. Details of road elevations are not at hand. Depending on the elevation of the access roads/ramps on the northern side of the route above local ground level, Alternative 1 may provide partial screening of the N2 route from land to the north. This would reduce the existing levels of ambient noise in the area. The assumed light road traffic travelling at low speeds on the underpass and access roads/ramps is not expected to offset the potential positive status. Alternative 2 would result in no change to existing noise levels in Houwhoek Village. It is estimated that the intensity of impact on the farm stall in its new location would be the same as at the present location. Recommendations: With regard to the potential benefits arising out of the Alternative 1, it is recommended that this alternative be considered. A one metre high wall should be erected along the northern edge of the access road/ramps to reduce noise emanating from vehicles on the ramp. During construction of the underpass of the Alternative 1, consideration should be given to replacing the existing road surface of the N2 in line-of-sight of Houwhoek village with lownoise porous asphalt. This would result in a significant reduction of existing ambient noise levels. In order to reduce the impact on the relocated farm stall it is recommended that the N2 in line-of sight of the farm stall be replaced with a low-noise surface. Assessment summary: IMPACT ALTERNATIVE 1 2 CRITERIA No mitigation Mitigation No mitigation Mitigation Extent Local Local Local Local Phase Operation Operation Operation Operation Duration Long term Long term Long term Long term Intensity Low Low Negligible Low Probability Probable Probable Probable Probable Significance Low Low Negligible Low Status Negative Positive Neutral Positive Confidence Low Low Low Low 50

57 Bot River Ramp Plaza The location of the proposed ramp plaza is shown in Figure 11. Assessment: There is no noise-sensitive area located close to the proposed ramp plaza. It is expected that there would be no impact. Recommendations: None 51

58 11.6 N2 - BYPASS BETWEEN HELDERZICHT AND FIRLANDS. Several alternative alignments have been proposed for the N2 bypass through Helderzicht. This section presents the results and assessment of calculated 18-hour L Aeq displayed by means of noise contours superimposed onto cadastral maps of the areas for the existing alignment and road traffic conditions and for the various proposed alternative road alignments without and with noise mitigation. These are displayed in Figures 14 through 22. The noise mitigation options take the form of noise barriers of different heights located approximately 10 metres from the road edge without and with the utilisation of a porous road surface. The contours represent the 18-hour L Aeq at a height of 1,4 metres above ground level in accordance with the requirements of the Noise Control Regulations. The Figures therefore contain no information regarding the levels of noise outside upper storey windows of multistorey buildings. The noise contour diagrams facilitate a general appreciation of the land areas that are presently exposed to particular levels of road traffic noise and how the area of land, and hence the number of residences, exposed to these noise levels are likely to change for the various alternative road alignment proposals and noise mitigation measures. The effects of noise mitigation measures are considered further in Section The proposed alternative alignments primarily occur in the vicinity of the Danie Ackerman Primary and Gordon High Schools. This Section therefore focuses on the predicted noise exposure to occupants of land in the immediate vicinity of the schools. The predicted noise exposure for the entire region between Helderzicht and Firlands is also included. Figures 14 through 23 portray the results of road noise prediction calculations performed in accordance with procedures contained in South African Bureau of Standards Code of Practice 0210 for Calculating and predicting road traffic noise. The influence of local noise shading by individual buildings or structures is not included. The procedures contained in SABS 0210 include the application of a constant correction of 3,5 db to the calculated 18-hour L Aeq for porous road surfaces such as open grade bitumen rubber. This constant correction has been used in all predictions contained in this report. However, experience has shown that this value is not constant and is dependent on vehicle speed and is highly dependent on surface texture. Use of modern low-noise porous asphalt surfaces can result in a reduction of 6 db or more compared to smooth dense asphalt at freeway speeds. This should be borne in mind when considering the different noise mitigation alternatives. The 18-hour L Aeq was estimated using traffic flow counts on a typical Tuesday for the N2 at Count Station 3016, Somerset West recorded in the CTO Yearbook This is reproduced in Figure 8. It has been found in numerous similar studies that the 18-hour L Aeq for the period 06:00 hrs till midnight is approximately equal to the 1-hour L Aeq using the 1-hour traffic count at mid trough between morning and afternoon peak traffic flows. Figure 13 shows that this occurs between 10:00 hrs and 14:00 hrs. The error in using this approximation has been found to be less than 1 db for typical hourly traffic flow distributions depicted in Figure

59 Westbound Eastbound Total FIGURE 13. Hourly traffic flow counts used for 18-hour L Aeq calculations. From Figure 13 the mid-trough hourly traffic flow is approximately 1000 vehicles per hour in each direction. This value of traffic flow was used to calculate the 18-hour L Aeq for the various alternative road alignments in this Section. The assumed mean speed on the existing and future freeway was 120 km/hr. During sound measurements conducted along the trunk road the mean speed of westbound traffic was judged to be 80 km/hr while that for eastbound traffic was judged to be 70 km/hr. This was based on driving at the same speed as traffic in both directions after completion of the sound measurements. A mean speed of 75 km/hr was therefore used for calculating the noise from traffic on the trunk road. 53

60 Existing road traffic. D. Ackerman & H. Gordon h l FIGURE 14. Calculated noise contours for existing road traffic with measured 1-hr L Aeq values superimposed. Sound measurements were conducted in the area of Helderzicht on Sunday 7 April 2002 between 14:30 hrs and 17:00 hrs. The measured 1-hour L Aeq values at the respective measurement locations are displayed against a white, circular background superimposed on the noise contour map in Figure 14. The calculated L Aeq values correlated closely with the measured values. Assessment: No residences in the area are exposed to 18-hour L Aeq exceeding 65 dba as contained in the Noise Control Regulations. The existing 18-hour L Aeq ranging between 59 dba and 65 dba on the school sites exceed the recommended maximum level of 50 dba outside classrooms (with windows open) in terms of SABS 0103 and exceed the 55 dba recommended by the World Health Organization. In terms of SABS 0103 the intensity of the existing noise impact is High with High significance. A large area of residential land is exposed to 18-hour L Aeq exceeding the 55 dba recommended by the World Health Organization and a 50 dba daytime level typical of a suburban district with little road traffic in terms of SABS The intensity of noise impact is Medium to High with Medium to High significance. 54

61 Assessment Summary: Assessment of existing noise impact on residential areas and school sites in terms of SABS CRITERIA Extent Period Duration Intensity Probability Significance Status Confidence IMPACT Local Existing Existing Medium to High Existing Medium to High Negative High 55

62 Alternative 1 Do nothing Traffic volumes will increase on Trunk Road 2 (T2) over time resulting in greater congestion and reduced mean speeds due to the controlled intersections. The increased volume of traffic will offset the reduced noise levels accompanying reduced speeds. Assessment: It is expected that there would be no significant change to the existing ambient noise levels in the medium term. With deterioration of the road surface the noise levels will increase with a Low estimated intensity of impact. The existing intensity of noise impact at the school is expected to remain High with High significance. The relative intensity of noise impact on residential land in doing nothing is expected to Low with Low significance. Recommendations: These recommendations are based on the results contained in Sections through and Section Resurface the T2 along its entire length where it bounds the school sites with lownoise porous asphalt when these surfaces need to be rehabilitated. Assessment summary: Assessment of the relative effect of doing nothing on residential areas and school sites. CRITERIA IMPACT Without Mitigation With Mitigation Extent Local Local Period Operation Operation Duration Long term Long term Intensity Low Low Probability Probable Probable Significance Low Low Status Negative Positive Confidence Low Low 56

63 Alternative 2 Upgrade the T2 to Freeway Standards. FIGURE 15. Calculated noise contours for upgrading the trunk road to freeway standards. Figure 15 shows the calculated noise contours for this alternative through Helderzicht. This is representative of the noise contours along the entire length of the proposed upgrade. Assessment: Increased road traffic volume and mean speed would extend the area exposed to 18- hour L Aeq in excess of 65 dba contained in the Noise Control Regulations including a significant area of existing residential land. In addition, a larger area of residential land would be exposed to 18-hour L Aeq in excess of the 55 dba recommended by the World Health Organization and 50 dba typical of a suburban district with little road traffic. However, areas exposed to high noise levels are contained along the existing trunk route. This is preferred compared to all other alternatives that would result in significantly larger areas of land exposed to noise from a realigned N2 (refer to subsequent Sections). The outdoor 18-hour L Aeq at the schools is increased further above the 55 dba recommended by the World Health Organization and the 50 dba daytime level typical of a suburban district with little road traffic in terms of SABS The intensity of the relative noise impact is expected to be Medium with Medium significance. 57

64 Recommendations: Surface the upgraded road with low-noise porous asphalt and erect a 5-metre high noise barrier close to the road edge along the school site and along the road where it passes through residential areas. These recommendations are based on the results contained in Sections through and Section Assessment summary: Assessment of residential areas and school sites. CRITERIA IMPACT Without Mitigation With Mitigation Extent Local Local Period Operation Operation Duration Long term Long term Intensity Medium Low Probability High High Significance Medium Low Status Negative Positive Confidence Medium Medium 58

65 Alternative 3 Bypass Helderzicht to the North with the N2 relocated on a Viaduct. Beyond Victoria Street join the N2 proclaimed route. FIGURE 16. Calculated noise contours for the N2 elevated on a viaduct above the trunk road. The surface of the elevated freeway is porous asphalt. Figure 16 shows the calculated noise contours only for the section of alternative 3 through Helderzicht. The remainder of alternative 3 follows the proclaimed N2 route that is considered in Section and shown in Figure 23. Assessment: High noise levels would be confined to existing areas of high noise levels along the existing route. It is expected that there would be a slight increase in land area exposed to 18-hour L Aeq values in excess of 65 dba. However it is expected that land further removed would be exposed to reduced levels of noise. 59

66 Recommendations: These recommendations are based on the findings contained in Section and 11.7 for two-storey buildings adjacent to the proposed route. Compliance with the Noise Control Regulations would require the N2 to be surfaced with low-noise porous asphalt plus a 3,5-metre high noise barrier located within 6 metres of the road edge where the N2 passes at grade along the school site and where it passes through residential areas at grade. A 1,5 metre high barrier would need to be erected along the edge of the elevated portion of the N2. This barrier height has been determined from several previous studies. Limiting the intensity of noise impact to medium in terms of SABS 0328 would require both the T2 and the N2 to be surfaced with low-noise porous asphalt. A 6-metre high noise barrier would need to be located within 6 metres of the edge of the N2 where the N2 passes at grade along the school site and where it passes through residential areas at grade. A 1,5 metre high barrier would need to be erected along the edge of the elevated portion of the N2. Assessment summary: Assessment of residential areas and school sites. CRITERIA IMPACT Without Mitigation With Mitigation Extent Local Local Period Operation Operation Duration Long term Long term Intensity Low Neutral to low Probability Probable Probable Significance Low Low Status Negative Neutral to positive Confidence Medium Medium 60

67 Alternative 4 Bypass Helderzicht to the South with N2 relocated through AECI property. FIGURE 17. Calculated noise contours for the N2 located to the south of Helderzicht. The surface of the N2 is porous asphalt. Figure 17 shows the calculated noise contours only for the section of alternative 4 through Helderzicht. The remainder of alternative 4 follows the proclaimed N2 route that is considered in Section and shown in Figure 23. Assessment: Notwithstanding the use of porous asphalt as a noise mitigation measure, the area of residential land exposed to 18-hour L Aeq exceeding the 50 dba typical of a suburban district with little road traffic and the 55 dba recommended by the World Health Organization is greatly increased compared to the existing situation. The estimated intensity would be High with a High significance. The 18-hour L Aeq at the schools remains unchanged compared to the existing situation. This is due to the proximity to the trunk road notwithstanding the assumed reduced traffic flow on the latter. 61

68 Recommendations: These recommendations are based on the findings contained in Section and 11.7 for two-storey buildings adjacent to the proposed route. Compliance with the Noise Control Regulations would require the N2 to be surfaced with low-noise porous asphalt plus a 3,5-metre high noise barrier located within 6 metres of the road edge. Limiting the intensity of noise impact to medium in terms of SABS 0328 would require the N2 to be surfaced with low-noise porous asphalt plus a 6-metre high noise barrier located within 6 metres of the road edge. Assessment summary: Assessment of residential areas and school sites. CRITERIA IMPACT Without Mitigation With Mitigation Extent Local Local Period Operation Operation Duration Long term Long term Intensity High Low to medium Probability High High Significance High Low to medium Status Negative Neutral to negative Confidence Medium Medium Alternatives 5, 6 and 7 - N2 on the proclaimed Route. Alternatives 5, 6 and 7 all follow the N2 proclaimed route with variations in elevation and noise mitigation. Alternative 5 proposes that the N2 be raised on a viaduct to pass over de Beers Avenue to just beyond the Lourens River crossing or, alternatively, to commence the viaduct east of de Beers Avenue. In the former case, where the elevated road surface would be 8 metres above surrounding ground level, the noise exposure on adjacent land would be similar to Alternative 3 considered in Section Along other sections with reduced elevation, the noise exposure would need to be calculated for the particular road elevations. This should be conducted during the detailed design stage of the project. Figures 18 to 22 display calculated noise contours adjacent to the N2 where it passes through Helderzicht. The various mitigation options displayed in Figures 19 through 22 apply to the remainder of land adjacent to the N2 proclaimed route. Figure 23 displays noise contours calculated for the approximate alignment of the entire route between Helderzicht and Firlands. 62

69 FIGURE 18. Calculated noise contours for the N2 located on the proclaimed route. No noise mitigation. Assessment: The area of residential land exposed to 18-hour L Aeq exceeding the 50 dba typical of a suburban district with little road traffic and the 55 dba recommended by the World Health Organization is greatly increased compared to the existing situation. The estimated intensity of impact would be High with High significance. The school buildings and a large area of residential land would be exposed to 18-hour L Aeq in excess of 65 dba. The predicted influences of various noise mitigation measures are shown in Figures 19 through 22. A noise barrier/wall separating the N2 from the school property is indicated extending up to the nearest residents to the school. The reduced effect of the wall at either end is to be noted. All wall heights are with reference to the road surface. The impact summary appears at the end of this Section. 63

70 Wall a. Without porous asphalt Wall b. With porous asphalt FIGURE 19. Noise mitigation: 3 metre high wall on school side of the N2 a. without and b. with porous road surface. 64

71 Wall a. Without porous asphalt Wall b. With porous asphalt FIGURE 20. Noise mitigation: 5 metre high wall on school side of the N2: a. without and b. with porous road surface. 65

72 Wall a. Without porous asphalt Wall b. With porous asphalt FIGURE 21. Noise mitigation: 7 metre high wall on school side: a. without and b. with porous road surface. 66

73 Wall FIGURE 22. Noise mitigation: 5 metre high wall both sides of N2 with porous road surface. Figure 22 shows the effectiveness of combining the use of a porous road surface with a 5 metre high wall in reducing the exposure to road noise on land located to the southwest of the wall. The 18-hour L Aeq would be less than presently experienced in this area as the land is also screened from noise emanating from the trunk road. The southwest wall is shown to commence at the position of the arrowhead. The reduced noise shading effect at the end of the wall and therefore the need to extend the wall well beyond the land to be protected from noise is clearly indicated. Figure 19 indicates that the combined effect of realignment of the N2 away from the northern boundary of the schools together with a 3 metre high wall erected along the southwest boundary of the school, within 10 metres of the nearest edge of the proposed N2, would reduce the 18-hour L Aeq to below the existing values over a large portion of the grounds of both schools for a receiver height of 1,4 metres above ground level. Figures 19 through 22 indicate that, due to the proximity of the trunk road to the schools, none of the additional noise mitigation measures relating to the N2 would further reduce the 18-hour L Aeq on the school sites. This would apply for a receiver height of 1,4 metres 67

74 above ground level as well as the noise levels 5 metres above ground level at the facades of the upper storeys of the schools. Recommendations: These recommendations are based on the findings contained in this Section and Section 11.7 for two-storey buildings adjacent to the proposed route. Compliance with the Noise Control Regulations would require the N2 to be surfaced with low-noise porous asphalt plus a 3,5-metre high noise barrier located within 6 metres of the road edge. However, the intensity of impact in terms of SABS 0103 would still be High. Limiting the intensity of noise impact to between Low and Medium in terms of SABS 0328 would require the N2 to be surfaced with low-noise porous asphalt plus a 6-metre high noise barrier located within 6 metres of the road edge. Where the N2 is elevated on a viaduct with the elevated road 8 metres above local ground level, a 1,5 metre high barrier would need to be erected along the edge of the elevated portion of the N2 (refer to Section ). For other elevations of viaduct, the required barrier height at the edge of the elevated road would need to be determined separately. Assessment summary: Assessment of residential areas and school sites. CRITERIA IMPACT Without Mitigation With Mitigation Extent Local Local Period Operation Operation Duration Long term Long term Intensity High Low to medium Probability High High Significance High Low to medium Status Negative Negative Confidence Medium Medium 68

75 a. Without porous asphalt b. With porous asphalt on the N2 only. FIGURE 23. N2 between Helderzicht and Firlands along proclaimed route. a. Conventional smooth dense asphalt road surface; b. Porous asphalt on N2 only; no noise barriers. 69