University Site: Land Between Madingley Road and Huntingdon Road (Parcel A); and

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1 Technical Note Project: North West Cambridge Transport Study To: Cambridgeshire County Council Subject: Additional Development Scenarios - University From: Atkins Date: 19/02/2009 cc: Executive Summary Background Information Atkins has been commission by Cambridgeshire County Council (CCC) to undertake transport modelling work to inform the Inspectors for the Examination of the North West Cambridge Area Action Plan, of the likely transport impact of a larger site footprint than that proposed in the submission draft Area Action Plan (AAP). The 2006/7 Atkins Study In Atkins undertook a study of the transportation impacts for the two development sites that are collectively known as North West Cambridge (NWC). The two land parcels are: University Site: Land Between Madingley Road and Huntingdon Road (Parcel A); and NIAB Site: Land between Huntingdon Road and Histon Road (Parcel B). Two levels of development were assessed: Allocated level of development in the Cambridge Local Plan (2006); A sensitivity test representing higher Levels of development to reflect the emerging/proposed development sites to the north west of the CNW allocated site and also land to the north of the NIAB site; The Transport Study identified measures to be considered for inclusion in a transport strategy for the north west quadrant consistent with the following principles; A predict, provide and promote strategy for trips by public transport, cycling and foot; and; A demand management approach for trips by private car. The study has informed the County Council input into the transport planning for both the NIAB development and the preparation of the North West Cambridge AAP Enlarged Site - Sensitivity Test To respond to the Inspectors request to consider the impact of a larger footprint option, this study has assessed the highway impact of additional residential development on the University site, beyond the higher levels of development already assessed in the 2006/7 Atkins Report. The two sensitivity tests are: Additional 300 residential dwellings; and, Additional 700 residential dwellings. Each was tested both with 1 and without 2 the package of measures recommended by the earlier study to reduce encourage non-car modes of transport and enable the preferred modal split to be 1 DTRWSM Development Trip Rate with Sustainable Measures 2 DTR Development Trip Rate /Transport Study supplement FINAL 20 Feb 1

2 achieved (i.e. no more than 40% of journeys for work to be made using the private car, excluding passengers). The figures of 300 and 700 were agreed before officers of the two district councils together with the University had made their assessment of the likely capacity of the additional land at 500 dwellings, due to the early need to commence the modelling work. It does however, provide a robust test of the likely additional dwellings if the Inspectors larger site option were to be adopted The results of the SATURN modelling suggest that if the development areas can achieve the DTRWSM then the additional 300 or 700 dwellings will not have a significant additional impact on the congested local highway conditions (the Base 2025 highway network is already congested). The results show that only relatively minor changes to traffic flows, queuing and delays occur when compared against the base level of development traffic conditions. If an additional 300 or 700 dwellings only achieve the DTR more significant changes could occur to local traffic conditions. In particular, due to increases in delay on Huntingdon Road and Madingley Road, local city centre traffic could reassign via Histon Road and the A14 as an alternative westbound route to Huntingdon Road and Madingley Road. Summary Conclusion In conclusion, the results of these modelling runs taking account of the extra dwellings demonstrate that there is not any additional significant impact upon the highway network in terms of capacity, delay and redirected traffic over that identified in the original study. However, the modelling results have shown that these extra dwellings can be acceptably accommodated, as long as a 40% or less modal share for car driver is achieved /Transport Study supplement FINAL 20 Feb 2

3 1. Background Information Atkins has been commissioned by Cambridgeshire County Council (CCC) to undertake additional development traffic modelling for a development area to the north west of Cambridge City Centre, known as Cambridge North West (CNW) /7 Atkins Report: Scenario & Option testing In Atkins undertook a study to examine impacts on transport and identify mitigation measures for two development sites that are collectively known as CNW. The two land parcels are: Parcel A University Site: Land Between Madingley Road and Huntingdon Road; and Parcel B NIAB Site: Land between Huntingdon Road and Histon Road, The AM Peak Hour SATURN traffic modelling (2025) that supported the study assessed the highway impact of a range of development and highway infrastructure options. Originally two landuse development scenarios were tested, an agreed level of development and a sensitivity test. The development levels under each scenario are summarised in Table 1.1. Table 1.1 Cambridge North West Development Levels Scenario 1 Allocated Development NIAB Land Scenario 2 Sensitivity Development NIAB Land Land Use Quantity Unit Land Use Quantity Unit Residential 1780 Dwellings Residential 2800 Dwellings Primary School 2.3 Hectares Primary School 4.6 Hectares Local centre 1 Hectare Local centre 1.6 Hectares Secondary School 8 Hectares Secondary School 8 Hectares Scenario 1 Allocated Development University Land Scenario 2 Sensitivity Development University Land Land Use Quantity Unit Land Use Quantity Unit Primary School 2.3 Hectares Primary School 3.8 Hectares Residential (Key Worker 50%) (Private 50%) Dwellings Residential (Key Worker 50%) (Private 50%) Dwellings Higher Education 14 Hectares Earth Science Faculty Hectares University related Research 6 Hectares University related Research (Academic Faculty) (Commercial) 100,000 50,000 50,000 Sq.m Local Centre 1 Hectare Local Centre 2.2 Hectares Student Housing 2,000 units In addition to the two land use scenarios, two highway infrastructure options were tested as part of the study. The two highway options were: /Transport Study supplement FINAL 20 Feb 3

4 Option A Orbital Link: Direct orbital link road between Madingley Road and Histon Road through each of the development sites; and Option B M11 Slip roads and Extended Park and Ride: Provision of northern slip roads at the M11 Junction 11 and a sinuous orbital link through both development sites between Madingley Road and Histon Road. This option also included an extension to the Madingley Park and Ride. The vehicle trip rates used to determine the number of additional vehicle movements generated by NIAB and the University site was predicted using the trip rates outlined in CCC Housing Trip Rates, Comparison of Surveys (October 2001). These trip rates are used as a starting point for all new developments in Cambridgeshire. For the purposes of this report these trip rates will be referred to as the Development Trip Rates (DTR). The trip rates for non-residential land-uses were predicted using the TRICS database. Following the initial SATURN modelling, and discussions with Cambridgeshire County Council and the University s transport consultants (Peter Brett Assoc.) it was decided that the DTR were not suitable for assessing trips generated by the residential elements of the CNW development. A new trip rate was derived to account for a package of measures to encourage sustainable modes of travel associated with the Preferred Transport Option for CNW (see below). For the purposes of this paper the reduced trip rates will be referred to as Development Trip Rates with Sustainable Measures (DTRWSM). The DTR and DTRWSM are show in Table 1.2. Table 1.2 CNW AM Peak Hour Car Driver Trip Rates per Residential Dwelling Source In Out Total Development Trip Rates Development Trip Rates with Sustainable Measures Preferred Transport Option The SATURN highway and development scenario option testing resulted in the development of a Preferred Transport Option (Option C). The preferred option can be summarised as follows: Sinuous orbital route through NIAB development site to discourage through traffic; Direct orbital route through the University development site to discourage existing rat-running on Storey s Way; and Development Scenario1-Allocated Development (land allocated within Cambridge City) with reduced vehicle mode share (shown in Table 1.2) to account for the potential impact of a package of measures to promote sustainable travel from the development area /Transport Study supplement FINAL 20 Feb 4

5 2. Aims and Objectives of this Technical Note The aim of this Technical Note is to assess the highway impact of additional residential development on the University site. CCC provisionally proposed two sensitivity tests: Additional 300 residential dwellings; and Additional 700 residential dwellings. South Cambridgeshire District Council (SCDC) and Cambridge City Council together with the University subsequently assessed the potential additional capacity as 500 dwellings on the University Site, but due to the project timescales the additional dwelling scenarios outlined above have been assessed. It was agreed with CCC that: An additional 300 and 700 dwellings on the University site would be added to the Development Scenario 2 which includes the higher level of development on the University and NIAB sites, assessed as part of the CNW Transport study (see Table 1.1); The Preferred Highway Option C would be used to assess the additional residential development; and Both the DTR and DTRWSM (preferred option) vehicle mode shares would be assessed for additional housing (see Table 1.2). 3. Strategic Traffic Modelling Assessment To be consistent with the original assessment the A14 Ellington to Fen Ditton SATURN model was used to assess the following scenarios: AM 2025 Base Case including Development Scenario 2, DTR Vehicle Mode Share, Highway Option C AM Peak 2025; AM 2025 Base Case including Development Scenario 2, DTRWSM Vehicle Mode Share, Highway Option C AM Peak 2025; AM 2025 Base Case Dwellings University Site including DTR Vehicle Mode Share; AM 2025 Base Case Dwellings University Site including DTRWSM Vehicle Mode Share; AM 2025 Base Case Dwellings University Site including DTR Vehicle Mode Share; and AM 2025 Base Case Dwellings University Site including DTRWSM Vehicle Mode Share /Transport Study supplement FINAL 20 Feb 5

6 3.1 AM Peak 2025 Base The Base model represents the forecast highway network in the vicinity of the development area under AM Peak 2025 traffic conditions with the CNW Development Scenario 2 and Highway Option C infrastructure included. Two base models have been produced using the DTR and DTRWSM vehicle mode shares. These models have been used as a base, against which the highway impact of the additional residential dwellings can be assessed. The AM Peak 2025 base model results are presented in the form of Queue/Saturation (Q/S) plots in Figures 3.1 to 3.3. The Q/S plots provide a visual representation of the queues that are predicted. Figures 3.1 and 3.2 show the results for the AM Base 2025 with DTR and DTRWSM respectively. The results for both models show significant queuing is predicted in the AM 2025 Peak Hour in the following locations: Huntingdon Road; Girton Interchange; and Histon Interchange. The CNW development and associated infrastructure results in significant queuing being predicted at the Madingley Road/University Orbital Road junction and to a lesser degree at the Histon Road/NIAB orbital route junction. Figure 3.3 shows the predicted change in queuing as a result of the reduced vehicle trip generation of the CNW due to a package of sustainable measures (the difference between Figures 3.2 and 3.1). The results in Figure 3.3 show that the reduced vehicle trip generation of CNW results in a significant reduction to queuing predicted on the University and NIAB orbital roads exiting onto Madingley and Histon Road respectively. The results suggest that the DTRWSM has significant benefits in terms of the amount of local congestion experienced on the orbital route when compared to the DTR. The main strategic impact is a reduced queue on the Histon Road northbound approach to the Histon interchange. However, in general the reduction in vehicle trip generation is not sufficient to have a significant impact on predicted queuing on the wider network. In summary, the AM Base 2025 model results suggest that the local highway network will be heavily congested at several locations during the Peak Hour. As a result of predicted future traffic flows significant queuing and delays are predicted inbound on Madingley Road and Huntingdon Road /Transport Study supplement FINAL 20 Feb 6

7 Technical Note Figure 3.1 Base 2025 Scenario 1 Q/S Plot /Transport Study supplement FINAL 20 Feb 7

8 Figure 3.2 Base 2025 Scenario 2 Q/S Plot /Transport Study supplement FINAL 20 Feb 8

9 Figure 3.3 Base 2025 Comparison Scenario 2 and Scenario 1 Q/S Plot /Transport Study supplement FINAL 20 Feb 9

10 Technical Note Additional Dwellings The 300 Dwellings with DTR and DTRWSM models represent the forecast highway network conditions in the vicinity of the development area under AM Peak 2025 traffic conditions including vehicular traffic generated by the additional 300 dwellings on the University site. The 300 Dwelling Model results have also been compared against the relevant AM 2025 Base models in Figures 3.4 and 3.5. Figures 3.4 and 3.5 show that in general the additional 300 dwellings results in minor increases to predicted queuing on the orbital link roads through NIAB and the University Sites. No significant changes in highway conditions are observed on the wider network. Comparing Figures 3.4 and 3.5 one significant difference is evident between the 300 Dwellings DTR and DTRWSM results when compared to their respective base results. The DTR results show a reduction in queuing on the northbound approach to the Histon Interchange with the additional 300 dwellings (Figure 3.4) whereas with DTRWSM there is no significant change in queuing at this junction. Further analysis of the SATURN model suggests that this reduction in queuing on the northbound approach to Histon Interchange is due to a reassignment of traffic in the Saturn Model. Figure 3.6 presents a comparison of the actual flows with the additional 300 DTR against the Base DTR. An increased left turn flow onto the A14 is shown due to a reduction in traffic using Huntingdon Road westbound. The queuing in the SATURN model has decreased despite the increase in flow through this junction approach because the left turn movement has a free flowing exist whereas the ahead movement is constrained. The DTRWSM results show that the lower number of additional vehicle trips being generated by the additional 300 dwellings do not result in any significant reassignment to highway network traffic movements (despite the additional 300 dwellings) and therefore no significant changes in highway congestion conditions. This is shown graphically in Figure 3.7. In summary, the additional traffic generation associated with the addition of 300 dwellings at the University Site does not have a significant additional impact on the congested local highway conditions. The results of the modelling suggest that the DTRWSM result in a less significant wider reassignment of traffic compared to the DTR /Transport Study supplement FINAL 20 Feb 10

11 Technical Note Figure 3.4 Comparison Q/S Plots Additional 300 Dwellings against Base Scenario /Transport Study supplement FINAL 20 Feb 11

12 Figure 3.5 Comparison Q/S Plots Additional 300 Dwellings against Base Scenario /Transport Study supplement FINAL 20 Feb 12

13 Figure 3.6 Comparison Actual Flows Additional 300 Dwellings against Base Scenario /Transport Study supplement FINAL 20 Feb 13

14 Figure 3.7 Comparison Actual Flows Additional 300 Dwellings against Base Scenario /Transport Study supplement FINAL 20 Feb 14

15 Technical Note Additional Dwellings The 700 Dwellings DTR and DTRWSM models represent the forecast highway network conditions in the vicinity of the development area under AM Peak 2025 traffic conditions including vehicular traffic generated by the additional 700 dwellings on the University site. The 700 Dwelling Model results have also been compared against the relevant AM 2025 Base models in Figures 3.8 and 3.9. Figure 3.8 and 3.9 show that compared to the base the additional 700 dwellings do not result in significant changes to queuing on the congested local highway network. However, Figure 3.7 shows that with DTR, there are increases in predicted queuing on the NIAB orbital link Road exit to Histon Road and on the Huntingdon Road approach to the southern orbital link junction. Analysis of the DTRWSM results in Figure 3.9 suggests that the additional 700 Dwellings results in no significant increases to queuing and congestion on the local highway network. The impact of the additional development traffic on local traffic flow assignment has also been analysed in Figures 3.10 and Figure 3.10 shows the difference in Actual Flows on the local highway network between the 700 additional dwellings DTR and the Base DTR. The results in Figure 3.10 show that the additional traffic generated by 700 Dwellings on the University site applying the DTR results in the reassignment of additional traffic northbound on Histon Road compared to the Base. The results suggest that due to increased flows from the University Site, a proportion of outbound traffic from Cambridge has reassigned from Madingley Road and Huntingdon Road to Histon Road to access the strategic road network. The results in Figure 3.10 show that with the DTRWSM trip generation for the 700 additional dwellings at the University site the local reassignment impact in the SATURN model is less significant. The predicted movement patterns between the 700 dwellings and Base model are generally consistent. In summary, the SATURN model results suggest that an additional 700 dwellings will not have a significant impact on the congested local highway network. However, use of the DTR result in localised reassignment of outbound traffic from Cambridge from Madingley Road and Huntingdon Road to Histon Road to access the strategic road network. The increase in flows due to the 700 dwellings DTRWSM are not sufficient to result in this significant reassignment of traffic flows on the local highway network /Transport Study supplement FINAL 20 Feb 15

16 Technical Note Figure 3.8 Comparison Q/S Plots Additional 700 Dwellings against Base Scenario /Transport Study supplement FINAL 20 Feb 16

17 Figure 1.9 Comparison Q/S Plots Additional 700 Dwellings against Base Scenario /Transport Study supplement FINAL 20 Feb 17

18 Figure 1.10 Comparison Actual Flows Additional 700 Dwellings against Base Scenario /Transport Study supplement FINAL 20 Feb 18

19 Figure 1.11 Comparison Actual Flows Additional 700 Dwellings against Base Scenario /Transport Study supplement FINAL 20 Feb 19

20 Technical Note 4. Summary and conclusions The results of the SATURN modelling suggest that if the development areas can achieve the DTRWSM then an additional 300 or 700 dwellings on the University site will not have a significant impact on the congested local highway conditions the (Base 2025 highway network is already congested). The results suggest only relatively minor changes to traffic flows, queuing and delays occur when compared against the base level of development traffic conditions. If an additional 300 or 700 dwellings achieve the DTR more significant changes could occur to local traffic conditions. In particular, due to increases in delay on Huntingdon Road and Madingley Road, local city centre traffic could reassign via Histon Road and the A14 as an alternative westbound route to Huntingdon Road and Madingley Road. In conclusion, the modelling results show that up to 700 additional dwellings (above that proposed in the draft submission AAP) will not result in significantly worse highway conditions compared to the CNW Base Development if the residential element of the development can achieve the DTRWSM. If the DTR is achieved then the introduction of additional delays is sufficient to cause some local reassignment of traffic and additional delays that are more likely to have a perceivable impact on localised congestion /Transport Study supplement FINAL 20 Feb 20