The effect of ground characteristics on optimum road-building distance for motorway noise control

Transcription

1 The effect of ground characteristics on optimum road-building distance for motorway noise control S. Sibel OZER 1 ; Nese YUGRUK AKDAG 2 1 Meliksah University, Turkey 2 Yildiz Technical University, Turkey ABSTRACT Today motorway noise is the primary source of noise pollution in most residential areas. The lack of codes that stipulate the minimum distance between roads and buildings at the planning stage and failure to implement them in zoning regulations makes it difficult to resolve this issue. Lack of coordination between regulations and lack of provisions determining distances for reducing noise in zoning regulations pose an important problem in Turkey s EU harmonization process. This study identifies noise sensitive buildings that are indicated in the The Regulation of Environmental Noise Assessment and Management and suggests minimum distances required for motorways that generate different levels of noise. These distances were determined by taking into consideration differences in surface absorption rates and slopes between the road and the building. Minimum distances were obtained with the help of a simulation program, and section noise maps. Results were formulated and presented to users. We hope that the data obtained here will guide zoning regulations in Turkey. Keywords: Noise Control, Urban Planning, Setback Distances I-INCE Classification of Subjects Numbers: 52.3, INTRODUCTION Noise is a subtle and prevalent pollution factor that affects human health and behavior, with negative effects that are not as visible as other types of pollution. In eliminating or mitigating these negative effects or, in other words, keeping noise at acceptable levels, planned execution of noise control stages is crucial. When noise control is taken into consideration at the urban planning stage, newly planned settlements or transportation axes can be developed in a systematic and healthy way, as well as existing settlements being protected and/or improved. This makes the urbanization process compatible with the changing and developing conditions in existing and new settlements. Moreover, noise control at the urban planning stage eliminates the need for control at the building stage and saves labor and other costs. Locating quiet building groups (residences, hotels, hospitals, schools, etc.) and recreation areas (parks, gardens etc.) far from traffic, outdoor activity facilities (stadiums, amusement parks etc.) and industrial noise should be a fundamental principle in urban planning. However, noise control to a large extent is put off until the building stage in Turkey, and in most buildings this issue is ignored at the building stage due to increased costs. This leads to individuals being subject to constant noise in their living spaces and a variety of negative effects. Provisions on noise pollution in national and international standards and regulations focus on determining the noise level limits according to the usage type of the area, while the desired relationship between areas that have different levels of noise are not described. The fact that this issue has not been included in the Regulation of Environmental Noise Assessment and Management [1] and the zoning regulations of Turkey, in addition to regulations on noise, results in the noise problem being put off until the building stage, although it can be solved more effectively and economically at the urban planning stage. Setback distances for buildings from motorways are not explicitly mentioned in the Planned Areas 1 sibelkozer@gmail.com 2 neseakdag@yahoo.com 7236

2 Type Zoning Regulation [2], published in the Official Gazette on October 2, 1985 and revised on June 1, The third chapter of the regulation, the Provisions for Land and Buildings section, Article 18 merely mentions yard depth: ARTICLE 18-1) Front yard depths: The minimum depth for front yards and road facing yards of buildings in residential areas must be 5.00 meters. The 5 meter distance between the building and the motorway prescribed by this front yard depth is often insufficient in terms of noise and leads to violation of acceptable threshold levels if no precautions are taken on the building surface. This paper aims to determine the optimum motorway-building relationship conditions for keeping motorway noise, which is a very widespread phenomenon, under control. To do so, minimum distances between noise sensitive buildings and motorways were calculated using sectional noise maps, changes in these distances due to different types of ground were analyzed, and the results are presented in the tables and charts below [3]. 2. DETERMINING THE CONDITIONS FOR MOTORWAY- BUILDING RELATIONSHIP IN MOTORWAY NOISE CONTROL 2.1 Data and Assumptions The most effective method for motorway noise control is at the urban planning stage, especially for high rise buildings, is increasing distance. To achieve acceptable levels of noise outside the building, it is important to determine the minimum distance between the motorway and the building. The assumptions that are evaluated in studies that aim to determine the optimum distance between motorways and buildings when there are no barriers on the roadside are shown in Table 1. Table 1 Assumptions for the study Noise level (1 km from the motorway): Sound power level: 65 dba, 70 dba, 75 dba, 80 dba, 85 dba. 79 db, 83 db, 113 db, 117 db, 123 db. 15 meters (4 lane road) Road width 21 meters (6 lane road) Building height 13 stories; h: 40 meters Ground between the motorway and the residential building Topography Acceptable external noise level for the residential area As ISO standard [4]; reflective semi-reflective absorbent Flat terrain; 0 slope Upwards slope towards the building; 30% slope Downwards slop towards the building; 30% slope Lday< 55 dba [1,5]. 2.2 Determining Optimum Distances Sectional noise maps are created using SoundPLAN 7.1 noise mapping simulation software, to determine the minimum distance between the motorway and the building for each condition shown in Table 1 [6]. These maps were created based on the NMPB_Routes-96 standard and the Lday evaluation unit. The maps for five different noise levels (motorway noise level of 65, 70, 75, 80 and 85 dba), three different ground effects ( 0, 0.6, 1) and three different topographic conditions (flat, downhill, uphill) are shown in Figure 1, while the minimum distances that attain the limits determined by the maps are shown in Table

3 min. distance for 55 dba (m) Figure 1 Section noise maps for three different topographical conditions and three different ground effects when motorway noise level is 65 dba Table 2 Minimum necessary distances according to different noise levels, ground effects and topographical conditions ground effects (reflective) (semi-reflective) (absorbent) slope up-wards flat up-wards flat up-wards flat downwards downwards downwards 65 dba dBA dba dba dba According to the results shown in Table 2: The necessary building distances for keeping under the limit values for noise, changes according to the type of the ground. When the ground is flat, the minimum distances for 65 dba noise levels for reflective, semi-reflective and absorbent grounds are 75 meters, 51 meters and 42 meters respectively. The minimum distances increase significantly as the noise level increases and for the highest level studied, which is 85 dba, the distances for different absorbencies of ground are 887 meters, 600 meters and 516 meters respectively. The minimum distances for the examples are 44% lower when the ground is absorbent than when the ground is reflective. When the ground between the building and the motorway has an upwards or downwards slope instead of being flat, the distances required increase significantly. Since motorways are linear sources of noise and sound waves are circular waves, the minimum necessary distance increases when the 7238

4 slope is downwards from the road, while it decreases when the slope is upwards from the road. For instance, when the ground is semi-reflective and the motorway noise level is 65 dba, the minimum distance for achieving the limit value on the building facade is 51 meters for flat ground, 78 meters (53 % increase) for downwards slope and 47 meters (8 % decrease) for upwards slope. The distance that satisfies the limit value varies in similar proportions for different topographies at all noise levels. Comparison between the effects of different ground types on minimum distance and comparison between the effects of different slopes on minimum distance can be seen in Figure 2 and Figure 3. Figure 2 Comparison between the effects of different ground types on minimum distance Figure 3 Comparison between the effects of different slopes on minimum distance 7239

5 2.3 Evaluation The results of the study that determined the minimum setback distances between the motorway and the building for different conditions to eliminate noise pollution were used in a formulation study to reach more generic outcomes that can aid designers. The current minimum motorway-building distance formulas stipulated by Turkey s ENCE Bylaw are shown in Table 3. In the process of making zoning plans, these formulas should be used to determine distances, and noise barriers should be used when sufficient distances cannot be achieved. Table 3 Minimum motorway-building distance formulas for all conditions Ground type Reflective surface Semi-reflective surface Absorbent surface Topography (Ground slope) Flat terrain Downwards slop Upwards slope Flat terrain Downwards slop Upwards slope Flat terrain Downwards slop Upwards slope Minimum motorway-building distance formulas (x = motorway sound level) y = 0,0378e 0,1197x y = 0,0625e 0,1149x y = 0,0342e 0,1173x y = 0,0216e 0,1208x y = 0,0305e 0,1217x y = 0,0183e 0,1223x y = 0,0144e 0,1242x y = 0,0182e 0,1267x y = 0,0116e 0,1266x 3. CONCLUSIONS In order to solve noise problems more effectively and economically, urban planning practices must take noise into consideration at the land-use planning stage. This will make new development areas be subject to stronger regional control. However, noise control over existing settlements is limited. Therefore, the decisions made at the planning stage are very important. This paper exemplifies the studies conducted within the project that aims to determine the optimum conditions that are required for noise control between motorways and buildings. This study s data should guide urban planning experts and architects in the creation of zoning plans and to provide data for the zoning regulations to be prepared for new development areas. ACKNOWLEDGEMENTS This paper was written as a part of the YTU Scientific Research Project. We would like to thank the YTU Scientific Research Project Coordination Unit for their support. REFERENCES 1. The Regulation of Environmental Noise Assessment and Management. Official Gazette with number 27601; The Zoning Regulation of Planned Areas, the Official Gazette with number 18916; Yugruk Akdag N, Ozer S. Kent planlamada gurultunun tasarim olcutu olarak degerlendirilmesi icin bir yaklasim [Determination of the optimum conditions between road and building for highway noise control]. YTU, DOP Project, Project num: DOP01; 2014-finished. 4. ISO Attenuation of sound during propagation outdoors -- Part 2: General method of calculation;

6 5. Future Noise Policy. European Commission Green Paper, Com (96), Commission of E.C; Brussels, Belgium; SoundPLAN 7.1 user manuel, Braunstein+Berndt Gmbh;