Technical Note: Impact of Boughton Heath S278 Works July 2013
SAIGHTON CAMP CHESTER COMMERCIAL ESTATES GROUP TECHNICAL NOTE: IMPACT OF BOUGHTON HEATH S278 WORKS UPON THE OPERATION OF THE LOCAL HIGHWAY NETWORK Bryan G Hall Consulting Civil & Transportation Planning Engineers Suite E8, Joseph s Well, Hanover Walk, Leeds, LS3 1AB Ref: July 2013
Report Reference No: Name Signed Date Note prepared by David Bell 14/07/2013 Note checked by Alex McGarrell 14/07/2013
EXECUTIVE SUMMARY This Technical Note considers the impact of the Section 278 works implemented at the Boughton Heath junction as part of the planning permission (ref: 08/02000/OUT) upon the operation of the junction and the surrounding highway network. The Note has been prepared to address the concerns of local residents over the impact of the works. The Section 278 works comprised the conversion and reconfiguration of the former five-arm roundabout form of control to a traffic signal form of control at the junction. The Boughton Heath Section 278 scheme was approved under planning permission (ref: 08/02000/OUT) for a mixed use redevelopment comprising 375 dwellings, 5,000 square metres of ancillary uses (A1, A2, A3, A4, A5 and D1), a new primary school (D1), open space, parking and ancillary landscaping on the front part of the Saighton Camp site (Area A). The Boughton Heath Section 278 works are covered under Condition No 15 of the planning permission. Construction of the works began in May 2011 and was substantially completed in February 2012. In order to assess the impact of the implementation of the works upon the operation of the local highway network, comprehensive traffic and queue surveys were carried out over the period Monday 25 February 2013 to Sunday 3 March 2013. The results of the surveys show that during the busiest morning and evening peak hours the Boughton Heath junction is operating within capacity with all demand getting through the junction. The results of the surveys on the wider highway network demonstrate that there is no evidence of a significant level of drivers using alternative routes to avoid the Boughton Heath junction. The personal injury collision records show that in the 17 month period post substantial completions of the works, there have been three personal injury collisions at the junction and none involved vulnerable road users such as pedestrians, pedal cyclists or motorcyclists. At the Area A Planning Appeal Inquiry held in March 2010 an agreed position was reached between the appellant and Cheshire West and Chester Council on the operation of the former Boughton Heath roundabout junction and the forecast operation of the implemented Section 278 traffic signal scheme. This agreed position was reached following the collection of comprehensive data on traffic flows and queues and undertaking detailed traffic modelling of the former roundabout layout and the traffic signal scheme implemented under the planning permission. The agreed opposition clearly demonstrated that in 2009, the Boughton Heath roundabout was operating over capacity with significant queuing and delays on all arms of the junction. Over the five year period (1 October 2006 to 30 September 2011) ie pre-implementation of the traffic signal scheme, 33 personal injury collisions occurred at the Boughton Heath junction including 6 involving cyclists and motorcyclists. This equated to an average rate of 6.6 personal injury collisions per annum.
At the Area A Inquiry detailed modelling evidence was submitted and agreed, demonstrating that following implementation of the Area A planning permission, including the Section 278 works, the Boughton Heath traffic signal junction would operate no worse than the former roundabout junction. Implementation of the Section 278 works at the Boughton Heath junction has provided the opportunity for the previously agreed forecast modelling to be revisited and re-validated against observed conditions. This in turn allows a comparison of the observed conditions at the Boughton Heath junction to be made against the position agreed at the Area A Inquiry. This comparison exercise has clearly demonstrated that following implementation of the Section 278 works, overall queuing at the junction has fallen by some 50% during the morning peak hour and some 45% during the evening peak hour, with the largest reduction in queues occurring on Caldy Valley Road, with a 76% reduction during the morning peak and 55% during the evening peak. The annual personal injury collision rate at the junction has fallen by 75% from a rate of 6.6 to 1.7. Using the updated 2013 survey results findings, updated modelling forecasts have been developed of the predicted situation, following full implementation of the Area A planning permission. The updated modelling shows that the forecast that total junction delays at the Boughton Heath junction are still lower than the forecast baseline position established at the Area A Planning Appeal Inquiry in 2010. In summary, the evidence collected in February 2013, post implementation of the Section 278 works at the Boughton Heath junction, has clearly demonstrated that there has been a material improvement in the operation of the junction when compared against the operational characteristics of the former five-arm roundabout method of control. The improvements include reduced queues and delays, a reduction in the number of personal injury collisions and improvements to pedestrian/cyclist crossing facilities at the junction. The updated forecast position at the Boughton Heath junction following full implementation of the Area A planning permission is a significant improvement over the forecast baseline position agreed at the Area A Planning Appeal Inquiry.
CONTENTS 1.0 INTRODUCTION 1 2.0 SCOPE OF SURVEYS COMMISSIONED 3 3.0 2013 SURVEY RESULTS AND FINDINGS 5 4.0 COMPARISON OF 2013 SURVEY RESULTS AGAINST 2009 SURVEYS AND AGREED BASELINE POSITION AT AREA A APPEAL INQUIRY 8 5.0 BOUGHTON HEATH JUNCTION MODELLING 13 6.0 SUMMARY AND CONCLUSIONS 15
APPENDICES Appendix BGH1 Location Plan of Traffic Survey Sites Appendix BGH2 Automatic Traffic Count Data Appendix BGH3 2013 Morning and Evening Peak Hour Network Flows Appendix BGH3A ANPR Data Appendix BGH4 Appendix BGH5 Appendix BGH6 Appendix BGH7 Queue Survey Results Cheshire Police Narration Report of Personal Injury Collisions at Boughton Heath Junction Agreed Baseline Arcady Modelling Results for Boughton Heath Junction 2009 Morning and Evening Peak Hour Network Flows Appendix BGH8 Difference between 2013 and 2009 Surveys Appendix BGH9 Personal Injury Collision Data 2008 to 2012 Appendix BGH10 Appendix BGH11 Appendix BGH12 Boughton Heath Operational Assessment 2013 Existing Flows Boughton Heath Operational Assessment 2009 Planning Appeal Inquiry Boughton Heath Operational Assessment Updated 2013 Survey Result Analysis
1.0 INTRODUCTION 1.1 This Note presents the findings of the usage of the local highway network in February 2013 in the vicinity of the Boughton Heath junction, Chester following substantial completion of the Section 278 works at the Boughton Heath junction implemented as part of the planning permission (ref: 08/02000/OUT) on the front part of the Saighton Camp site (Area A) for a mixed use redevelopment comprising 375 dwellings, 5,000 square metres of ancillary uses (A1, A2, A3, A4, A5 and D1), a new primary school (D1), open space, parking and ancillary landscaping. 1.2 Construction commenced on implementing the Area A planning permission in 2012 and all the required section 278 works covered under Condition No s 15 and 17 of the permission have been substantially competed including the traffic signal scheme at the Boughton Heath junction. The Boughton Heath junction works were substantially completed in February 2012. 1.3 In addition to the Section 278 works implemented as part of the Area A outline planning permission (ref: 08/02000/OUT), the Highways Agency implemented traffic signals scheme at the A51/A55 roundabout at the same time as the Boughton Heath junction works. 1.4 The purpose of this Note is to provide an update on the use and operational characteristics of the Boughton Heath junction following commencement of implementation of the Area A planning permission and substantial completion of the highway works outlined in paragraph 1.2 and 1.3. The Note also compares the updated survey results with survey data collected in 2009 pre commencement of the Area A development and associated offsite S278 highway works. 1.5 This Note is split into the following further sections. Section 2.0 Section 3.0 Section 4.0 Scope of the Surveys Commissioned This section describes the scope of the surveys commissioned. Results and Initial Finding This section presents the results and initial findings of the commissioned surveys. It also presents updated personal injury collision data for the Boughton Heath junction. Comparison of the 2013 Survey Results with 2009 Survey Results 1
This section compares the 2013 survey results with the 2009 surveys commissioned in 2009 as part of the Area A planning application (ref: 08/02000/OUT). Section 5.0 Section 6.0 Boughton Heath Junction Modelling This section presents forecast modelling of the Boughton Heath junction following full implementation of the Area A planning permission. It also compares the forecast modelling results using the 2013 survey data with the forecast modelling results agreed with Cheshire West and Chester Council at the Area A Planning Inquiry. Summary and Conclusions This section presents the summary and conclusion on the Note s findings. 2
2.0 SCOPE OF SURVEYS COMMISSIONED 2.1 This Section describes the scope of the surveys carried out post implementation of the Section 278 works at the Boughton Heath junction to establish the operating conditions on the local highway network. 2.2 In order to establish the existing usage and operating conditions on the local highway network the following traffic and queue surveys were carried out on Tuesday 26 February 2013. In addition to the surveys carried out on the Tuesday, automatic traffic counters were installed on a number of highway links over the two week period Monday 25 February 2013 to Sunday 3 March 2013 to ensure that the results of the surveys carried out on Tuesday 26 February 2013 were representative. The locations of the survey sites are shown on the plan at Appendix BGH1. Table 2.1 - Full Classified Junction Turning Counts and Queue Length Survey Junction Caldy Valley Road/A5115 Whitchurch Road/A41 Ring Road/A41 Whitchurch Road/A55 Slip Roads Littleton Lane/A51 Tarvin Road/Hare Lane Pearl Lane/A41 Ring Road Rowton Bridge Road/A41 Whitchurch Road Time Period 7:00am to 7:00pm 7:00am to 10:00am 3:00pm to 7:00pm 7:00am to 10:00am 3:00pm to 7:00pm 7:00am to 10:00am 3:00pm to 7:00pm Table 2.2: Origin-Destination Registration Plate Surveys Route Direction Time Period Route 1 Rowton Bridge Road/A41 Whitchurch Road to Pearl Lane/A41 Ring Road and Littleton Lane/A51 Tarvin Road Pearl Lane/A41 Ring Road to Littleton Lane/A51 Tarvin Road and Rowton Bridge Road/A41 Whitchurch Road 7:00am to 10:00am 3:00pm to 7:00pm Route 2 Toll Bar Road/A41 Ring Road Toll Bar Road/ A41 Whitchurch Road 7:00am to 10:00am 3
Table 2.3: Automatic Traffic Counts Location Caldy Valley Road A5115 Whitchurch Road A41 Ring Road A41 Whitchurch Road Time Period 24 Hours Monday 25 February 2013 to Sunday 3 March 2013 24 Hours Monday 25 February 2013 to Sunday 3 March 2013 24 Hours Monday 25 February 2013 to Sunday 3 March 2013 24 Hours Monday 25 February 2013 to Sunday 3 March 2013 4
3.0 2013 SURVEY RESULTS AND FINDINGS 3.1 This Section presents the results and findings of the 2013 traffic surveys described in Section 2.0. These survey results provide an updated evidence base to assess the impact of implementation of the Section 278 works, including at the Boughton Heath junction on the operation of the local highway network. 3.2 The 2013 survey results identify that the morning peak hour is 8:00am to 9:00am and the evening peak hour is 5:00pm to 6:00pm. Summary results of the Automatic Traffic Count data for the morning and evening peak hours is attached at Appendix BGH2 with the date of the full classified turning count surveys highlighted on the graphs. The graphs show that Tuesday 26 February 2013 was representative of the weekday morning and evening peak hour flows on the highway network over the period Monday 25 February 2013 to Sunday 3 March 2013. 3.3 The results of the full classified junction turning counts for the morning and evening peak hours are summarised on the traffic diagrams at Appendix BGH3. They show that the total vehicle movements at each junction during the morning and evening peak hours were as follows: Table 3.1: Total No of Movements (vehicles) AM Peak Hour PM Peak Hour Boughton Heath Junction 3937 3802 3.4 The key findings of the origin-destination survey data using Automatic Number Plate Recognition (ANPR) technology outlined in paragraph 2.2 are summarised below with the data attached at Appendix BGH3A. During the morning peak hour some 21 car drivers turn right into Rowton Bridge Road from A41 Whitchurch Road and travel through Christleton Village to either Pearl Lane or Littleton Lane. During the evening peak hour some 14 car drivers turn off A41 Ring Road and A51 Tarvin Road and travel through Christleton Village onto Rowton Bridge Road and onto A41 Whitchurch Road. During the morning peak hour some 10 car drivers used Toll Bar Road to travel between A41 Ring Road and A41 Whitchurch Road. 5
3.5 The results of the queue surveys at the Boughton Heath junction are attached at Appendix BGH4. Set out in the table below is a summary of the average queue lengths at the Boughton Heath junction for both the morning and evening peak hours. Table 3.3: Boughton Heath Junction Queue Survey Results Approach Average Queue (Vehicles) AM Peak Hour PM Peak Hour Caldy Valley Road 13 12 A5115 Whitchurch Road 17 11 A41 Ring Road 20 17 A41 Whitchurch Road 34 16 A55 Slips 17 19 Total 101 75 3.6 Since 2009, construction and occupation of the Area A planning permission has commenced, in addition to the on-going implementation of the Crownfields residential development. On Tuesday 26 February 2013, the Crownfields development and Area A site generated the following number of vehicle movements during the morning and evening peak hours. These movements included construction vehicle movements generated by both the Crownfields and Area A development sites. Table 3.5: Existing Vehicle Movements Generated by Crownfields and Area A Time Period Arrivals Departures Total Morning Peak Hour 44 70 214 Evening Peak Hour 59 52 111 6
Boughton Heath Junction Personal Injury Collision Data 3.7 Updated Personal Injury Collision Data Records for the Boughton Heath Junction have been obtained from Cheshire Police. During the period 01 January 2012 to 31 December 2012 (ie post substantial completion of the Section 278 works) there has only been one recorded personal injury collision at the Boughton Heath junction. This collision was of serious severity and occurred at 3:40pm on Monday 23 April 2012 at the Toll Bar Road/A41 Ring Road junction some 50.0 metres to the north of the Boughton Heath junction. The collision involved a car driver attempting to turn right out of Toll Bar onto A41 Ring Road colliding with a vehicle travelling southbound on A41 Ring Road towards the Boughton Heath junction. Two lanes of traffic on A41 southbound stopped to allow the vehicle emerging from Toll Bar but the driver failed to see an approaching vehicle in the third lane and a collision occurred between the two vehicles. The record of the collision identifies that the likely contributory factors are a poor turn or manoeuvre and failure to look properly. Since the collision occurred, yellow box road markings were introduced in August 2012 across the Toll Bar junction to assist drivers turning in and out of the junction. The Narrative report of this collision provided by Cheshire Police is attached at Appendix BGH5. 3.8 There is a time period between a personal injury collision occurring and the recorded data being processed and uploaded to the publicly available Cheshire Police database. The period 1 January 2013 to date is not covered by the records provided, however Cheshire Police have advised the Local Highway Authority, that for this period, two slight injury collisions have occurred. A slight injury collision occurred at 19:42 hours on Saturday 30 March involving a driver attempting to turn right from the A55 towards A41 too early and colliding with a vehicle exiting the junction heading towards A55. On 19 April 2013 a slight injury collision occurred involving a vehicle turning right into Toll Bar Road from A41. The narrative report records for both these collisions are not publically available to allow the identification of the contributory factors. 3.9 In summary over the 17 month period between 1 March 2012 to 1 June 2013 there have been three personal injury collisions at Boughton Heath junction. This equates to a collision rate of 1.7 collisions per annum. 7
4.0 COMPARISON OF 2013 SURVEY RESULTS AGAINST 2009 SURVEYS AND AGREED BASELINE POSITION AT AREA A APPEAL INQUIRY 4.1 This Section compares the findings of the 2013 survey results described in Section 3.0 against the agreed baseline position using the 2009 surveys reached at the Area A Planning Appeal Inquiry. The agreed baseline position included a detailed assessment of the operation of the former five-arm roundabout method of control at the Boughton Heath junction. This agreed position included detailed modelling of the roundabout using the results of traffic and queue data collected in 2009. This Section therefore compares the 2013 survey results against both the survey data collected in 2009 and traffic modelling results of the former roundabout. Change in Traffic Levels on Network 4.2 This section compares the results of the 2013 survey of the Boughton Heath junction post substantial completion of the Section 278 works against the baseline position using data collected in 2009 (i.e. pre-implementation of Section 278 works) agreed at the Area A Inquiry held in March 2010. At the Area A appeal inquiry the Supplementary Statement of Common Ground identifies the base ARCADY model for the Boughton Heath roundabout that was agreed as being representative of queue datasets collected in October 2009. Set out in Appendix BGH6 are the previously agreed ARCADY model outputs of the operation of Boughton Heath Roundabout for 2009, 2011 and 2021 without Area A development. 4.3 The results attached at Appendix BGH6 clearly show the former roundabout was operating significantly above capacity during both the morning and evening peak hours in 2009 and forecast to continue to operate well over capacity in 2021. 4.4 As noted in paragraph 1.4, in 2009 full classified turning count and queue surveys of the local highway network were carried out prior to the implementation of the Area A Section 278 works and these were used to develop the agreed baseline position model of the former Boughton Heath roundabout junction outlined in paragraphs 4.1 to 4.2. The results of the 2009 surveys are summarised on the traffic diagrams at Appendix BGH7 with the differences between the 2009 and 2013 surveys summarised on the diagrams at Appendix BGH8. Set out in the table below is a summary of the changes in total junction movements during the morning and evening peak hours. 8
Table 4.1: Total Number of Movements (Vehicles) Junction AM Peak Hour 2009 2013 Change % Change PM Peak Hour 2009 2013 Change % Change Boughton Heath Junction 4680 3937-743 -16% 4680 3802-878 -19% 4.5 In overall terms, the survey results show that during the morning peak hour, the number of vehicle movements has fallen some 16% between 2009 and 2013 with a 19% reduction during the evening peak hour. These changes in traffic levels are typical of trends showing a reduction in traffic levels on a national, regional and local level as a result of people s changing travel patterns. Data for the entire city of Chester shows there has been an 8% decline in traffic levels across the city between 2004 and 2013. 4.7 During the morning peak hour traffic flows on the Caldy Valley Road approach have increased by some 11% and on all other approaches the flows are in the range of 17% to 25% lower than the 2009 figures. During the evening peak hour flows on Caldy Valley Road have remained relatively unchanged with flows on all other approaches varying between 9% and 21% lower than the 2009 levels. The changes in the turning proportion movements at the junction show that during the morning and evening peak hours there has been a significant change in the distribution of turning proportions to/from Caldy Valley Road, with the A41 Ring Road to Caldy Valley Road movement and vice versa increasing by some 64% during the morning peak hour and some 27% during the evening peak hour. The A41 Whitchurch Road to Caldy Valley Road movement and vice versa has reduced by some 66% during the morning peak hour and some 58% during the evening peak hour. Comparison of Queue Survey Results 4.9 As noted in paragraph 2.1 queue data has been collected at the Boughton Heath junction outlined in Table 2.1. During the morning and evening peak hours the maximum queue for each 5 minute period was observed. Using the maximum queue datasets for each 5 minute period an average queue has been calculated for each junction arm for both the morning and evening peak hours. Average queues have been calculated for the morning and evening peak hours as they represent typical queuing levels across the entire peak hour periods. During all periods of the day there will be fluctuations in queuing that reflect fluctuations in traffic level patterns, including during the peak hours. Therefore average queues 9
have been calculated and used as they represent typical operating conditions during the peak hours that are also consistent with the queuing calculation methodology used in junction modelling software programs such as ARCADY and LinSig. This provides a sound methodology of comparing the 2013 queue data sets against the agreed baseline position of the Area A Inquiry using the 2009 queue data set. AM Peak Hour Table 4.3: Boughton Heath Junction Average Queues PM Peak Hour : Agreed 2009 Modelling 2013 % Change Queue % Change in Traffic Flow Agreed 2009 Modelling 2013 % Change Queue % Change in Traffic Flow Caldy Valley Road 55 13-76% +11% 27 12-55% -3% A5115 Whitchurch Road 33 17-48% -18% 50 11-78% -9% A41 Ring Road 24 20-17% -17% 27 17-37% -21% A41 Whitchurch Road 47 34-28% -20% 16 16 No change -21% A55 Slips 44 17-61% -25% 17 19 +12% -10% Total 203 101-50% -16% 137 75-45% -19% The results show that the total average queues at the junction have fallen by 50% during the morning peak hour and 45% during the evening peak hour. In comparison, total traffic movements have only fallen by 16% and 19% during the morning and evening peak hours respectively. The largest reduction in queues has occurred on Caldy Valley Road with a 76% reduction during the morning peak and 55% reduction during the evening peak and this is despite traffic levels increasing on this approach. It is noted that on some arms the level of queuing has increased, such as the A55 slip roads during the evening peak hour. However, these queues clear during each cycle, demonstrating that these approaches are operating within capacity. The increase in queue does not necessarily indicate a problem, as the queuing characteristics of a traffic signal junction are different to priority controlled roundabout form of control. The queue survey results clearly demonstrate that the Section 278 works at Boughton Heath are a significant 10
contributory factor at the reduced level of queuing in comparison with the queues that were occurring in 2009 when the junction was operating as a five-arm roundabout. Comparison of Personal Injury Collisions at Boughton Heath Junction Pre and Post Implementation of Section 278 Works 4.10 The graph below shows the annual rate of personal injury collision that have occurred at the Boughton Heath junction over the period 1 January 2007 to 31 December 2012 for complete calendar years. Graph 4.1 No. (collisions per annum) 10 9 8 7 6 5 4 3 2 1 0 Personal Injury Collision Rate at Boughton Heath Junction Substantial completion of Boughton Heath s278 Works 2007 2008 2009 2010 2011 2012 Year Graph 4.1 shows that pre-implementation of the Section 278 works the average annual rate is 6.4 collisions and this falls to 1.0 collision per annum post implementation. Full calendar years have been shown on the graph to provide a statistically sound sample size for comparison purposes. 4.11 Graph 4.1 shows the collision rate for the full calendar years, however, the collision records have been provided for 1 October 2006 to 31 December 2012. Over the period 01 October 2006 to 30 September 2011 (ie pre implementation of the traffic signal scheme) 33 personal injury collisions occurred at the Boughton Heath junction, of which two were serious and 31 were slight. The two serious collisions also involved motorcyclists and four of the slight collisions involved 11
cyclists and motorcyclists. Over the five year period, the number of collisions equated to an average rate of 6.6 personal injury collisions per year. In comparison, the personal injury data post implementation of the works (ie between 1 March 2012 to 31 May 2013) shows that the accident rate has fallen to 1.7 personal injury collisions per year with none involving vulnerable road users such as pedestrians, cyclists or motorcyclists. This equates to a 75% reduction in the annual personal injury collision rate at the junction following implementation of the Section 278 works. 4.12 The plans at Appendix BGH9 show the location of the personal injury collisions that have occurred on the wider highway network for each full calendar year over the period 1 January 2008 to 31 December 2012. The Study Area summary sheet and full records also at Appendix BGH9 shows that in the wider area beyond the Boughton Heath junction the total annual number of personal injury collisions has not materially changed following substantial completion of the Boughton Heath Section 278 works. 4.13 The plans attached at Appendix BGH9 demonstrate that there has been no material change in the pattern of personal injury collisions occurring on the local highway network following implementation of the Section 278 works. 12
5.0 BOUGHTON HEATH JUNCTION MODELLING 5.1 This Section presents updated modelling of the Boughton Heath junction using the results of the recent 2013 surveys. Using this updated model, updated forecasts following full implementation of the Area A planning permission have been carried out for the Boughton Heath junction and compared against the forecast position agreed at the Area A Inquiry. 5.2 At the Area A Inquiry the future operation of Boughton Heath traffic signal scheme was modelled using the LinSig modelling tool. The LinSig modelling tool is an industry standard software application for modelling and predicting the operational characteristics of traffic signal junctions including complex junctions such as the Boughton Heath junction. At the Area A Inquiry, a LinSig model was developed and agreed based upon a preliminary layout design. Following the granting of planning permission, as is common practice, a detailed design of the layout, including detailed specifications of the traffic signal method of control, was carried out under the terms of the Section 278 Agreement. Through the detailed design and implementation stage, the design has gone through a number of iterations, resulting in amendments to the input parameters used in the LinSig modelling software. These amendments include for example, changes to cycle times, green times and offsets. 5.3 Using the updated traffic signal control input parameters and the results of the 2013 traffic surveys, the LinSig model developed for the Area A Inquiry has been updated and re-validated. The updated LinSig modelling results for 2013 are attached at Appendix BGH10 and are representative of observed conditions. 5.4 In order to demonstrate that the Boughton Heath Section 278 works have delivered the benefits forecast at the Area A Planning Appeal Inquiry, the junction has been modelled at a forecast year of 2023 using the results of the 2013 surveys and assuming full implementation of the Area A planning permission and other unimplemented committed developments such as Crownfields, the Sainsbury s store extension and the Waitrose development. The Waitrose development was granted planning permission in 2012 (i.e. post implementation of the Boughton Heath Junction S278 works) 5.5 Using the LinSig modelling tool, the existing 2013 flows have been input into the model and the results validated against the 2013 queue survey results. The results are summarised at Appendix BGH10. 13
5.6 The 2021 forecast modelling results of the Boughton Heath junction using the 2009 survey results presented to the Area A Planning Appeal Inquiry are attached at Appendix BGH11. 5.7 An important point to note is that the traffic signal mitigation measures were agreed on the basis they would ensure that the junction would operate no worse than the baseline position of the former roundabout junction operating over capacity in the form of a 5 arm roundabout. 5.8 Using the LinSig modelling tool which has been updated and validated against the 2013 survey findings, updated forecast analyses using the results of the 2013 surveys have been undertaken. The results are attached at Appendix BGH12 and compared against the agreed Area A Inquiry forecast results at Appendix BGH11 for ease of reference. The updated modelling results clearly demonstrate that using the updated survey data evidence there will still be a significant improvement in the operation of the Boughton Heath junction over the predicted situation of the former roundabout agreed at the Area A Planning Inquiry in 2010. 14
6.0 SUMMARY AND CONCLUSIONS 6.1 This Section sets out a summary and conclusions drawn from the technical analysis in this Technical Note. 6.2 This Note presents the initial findings of the usage of the local highway network in the vicinity of the Boughton Heath junction, Chester following substantial completion of the Section 278 works at the Boughton Heath junction implemented as part of the planning permission (ref: 08/02000/OUT) on the front part of the Saighton Camp site (Area A) for a mixed use redevelopment comprising 375 dwellings, 5,000 square metres of ancillary uses (A1, A2, A3, A4, A5 and D1), a new primary school (D1), open space, parking and ancillary landscaping. 6.3 This Note provides up to date survey data on the use and operation of the local highway network following commencement of implementation of the Area A planning permission and substantial completion of the S278 highway works, including the Boughton Heath junction works. The Note also compares the up to date survey results with survey data collected in 2009 pre commencement of the Area A development and associated offsite S278 highway works. 6.4 In order to establish the existing usage and operating conditions at the Boughton Heath junction traffic and queue surveys were carried out on Tuesday 26 February 2013. In addition to the surveys carried out on the Tuesday, automatic traffic counters were installed on a number of links over the two week period Monday 25 February 2013 to Sunday 3 March 2013 to ensure the results of the surveys carried out on Tuesday 26 February 2013 were representative 6.5 The survey results at the Boughton Heath junction show there has been a 16% fall in total junction movements in the morning peak hour and 19% fall during the evening peak hour. Boughton Heath Junction 6.8 During the morning peak hour traffic flows on the Caldy Valley Road approach have increased by some 11% and on all other approaches the flows are in the range of 17% to 25% lower than the 2009 figures. During the evening peak hour flows on Caldy Valley Road have remained relatively unchanged with flows on all other approaches varying between 9% and 21% lower than the 2009 levels. The changes in the turning proportion movements at the junction show that during the morning and evening peak hours there has been a significant change in the 15
distribution of turning proportions to/from Caldy Valley Road, with the A41 Ring Road to Caldy Valley Road movement and vice versa increasing by some 64% during the morning peak hour and some 27% during the evening peak hour. The A41 Whitchurch Road to Caldy Valley Road movement and vice versa has fallen by some 66% during the morning peak hour and some 58% during the evening peak hour. 6.9 The results show that the total average queues at the junction have fallen by 50% during the morning peak hour and 45% during the evening peak hour. In comparison, total traffic movements have only fallen by 16% and 19% during the morning and evening peak hours respectively. The largest reduction in queues has occurred on Caldy Valley Road with a 76% reduction during the morning peak and 55% reduction during the evening peak and this is despite traffic levels increasing on this approach. It is noted that on some arms the level of queuing has increased, such as the A41 ring Road during the morning peak hour and A41 Whitchurch Road during the evening peak hour. However, these queues clear during each cycle, demonstrating that these approaches are operating within capacity. The queue survey results clearly demonstrate that the Section 278 works at Boughton Heath are a significant contributory factor at the reduced level of queuing in comparison with the queues that were occurring in 2009 when the junction was operating as a five-arm roundabout. 6.11 The key findings of the origin-destination surveys outlined in paragraph 2.1 are summarised below. During the morning peak hour some 21 car drivers turn right into Rowton Bridge Road from A41 Whitchurch Road and travel through Christleton Village to either Pearl Lane or Littleton Lane. During the evening peak hour some 14 car drivers turn off A41 Ring Road and A51 Tarvin Road and travel through Christleton Village onto Rowton Bridge Road and onto A41 Whitchurch Road. During the morning peak hour some 10 car drivers used Toll Bar Road to travel between A41 Ring Road and A41 Whitchurch Road. Comparison of Personal Injury Collisions at Boughton Heath Junction Pre and Post Implementation of Section 278 Works 6.12 The personal injury data post implementation of the works shows that the accident rate has fallen to one personal injury accident per year and no vulnerable road users such as cyclists or motorcyclists were involved. This equates to an 75% reduction in the annual personal injury collision rate at the junction post implementation of the Section 278 works. 16
6.13 Using the LinSig modelling tool which has been validated against the 2013 observed queues, updated forecast analyses using the results of the 2013 surveys have been carried out. The updated modelling results clearly demonstrate that using the updated survey data there will still be a significant improvement in the operation of the Boughton Heath junction over the baseline position agreed at the Area A Planning Inquiry in 2010. 6.14 In summary the updated survey data shows that the S278 works at the Boughton Heath junction have delivered improvements over and above the benefits of the overall reduction in traffic levels on the network since 2009. The personal injury collision rate at the Boughton Heath junction has fallen by some 75% following implementation of the S278 works. The results of the origin destination surveys also demonstrate that the level of through traffic movements through Christleton Village is not significant. The updated forecast position at the Boughton Heath junction following full implementation of the Area A planning permission is a significant improvement over the forecast position of the former roundabout agreed at the Area A Planning Appeal Inquiry held in March 2010. 17
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