2186 leckhampton saturn modelling note final - … · peter evans partnership tn23 atkins saturn...

Peter Evans

Partnership

TN23 Atkins Saturn Modelling April 2014

2186 LAND AT KIDNAPPERS LANE, LECKHAMPTON

TRANSPORT NOTE 23 – GCC / ATKINS SATURN MODELLING

1.0 INTRODUCTION

1.1 This note accompanies the planning application for Land at Kidnappers Lane, Leckhampton, Cheltenham (ref 13/01605/OUT) to provide the technical notes of the Saturn modelling undertaken to inform the application. Discussions with Gloucestershire County Council (GCC) and the Highways Agency (HA) regarding the application have identified the need to consider the impact of the proposals on a wider area basis, rather than within the immediate vicinity of the site only. Peter Evans Partnership (PEP) commissioned Atkins on behalf of GCC to undertake Saturn strategic traffic modelling using the Central Severn Vale (CSV) model to assess the effect of the development.

1.2 Outputs from the modelling have been utilised within the Transport Assessment September 2013 (TA) and Supplementary Traffic Note January 2014, as well as in the HA Paramics modelling for the Strategic Road Network.

1.3 The traffic flows used in the modelling do not take into account reductions in traffic generation or existing traffic anticipated as a result of transport measures and Travel Plans provided with the application.

2.0 SATURN MODELLING SCENARIOS

2.1 Saturn modelling was undertaken using GCC’s Central Severn Vale (CSV) model. Pre-application discussions were held with GCC and the HA regards the forecasting methodology for modelling. The scenarios modelled include 2014 as opening year for HA purposes and 2023 as forecast year. Joint Core Strategy (JCS) housing sites have been included in all scenarios according to the likely build-out rates of each development. More details of this are provided in Appendix 9 of the TA.

2.2 The modelling was undertaken in two stages. In September 2012 modelling for 2023 was undertaken assessing the ‘with’ and ‘without’ Leckhampton scenarios. At the time it was envisaged that there would be in the order of 1,200 dwellings at the Leckhampton site. The results of these model runs were reported in the Atkins Technical Note TN05, provided at Attachment 1.

Peter Evans

Partnership


2.3 TN05 provides a summary of the four scenarios modelled in the September 2012 modelling. These were:

• Scenario 1: 2023 Base; • Scenario 2: 2023 Base + Leckhampton; • Scenario 3: 2023 Base + All JCS development including Leckhampton; and • Scenario 4: 2023 Base + All JCS development excluding Leckhampton.

2.4 In this case the Leckhampton development refers to the Illustrative Masterplan area, which includes 1,200 dwellings.

2.5 In September 2013 further modelling was commissioned following a change in housing numbers to reflect a smaller application site. The site within the application boundary includes up to 650 houses and other uses. The remaining 550 houses within the Illustrative Masterplan area have therefore been included in the ‘without Leckhampton’ scenario.

2.6 The September 2013 modelling also included 2014 scenarios as an opening year assessment for HA purposes.

2.7 A further sensitivity test was undertaken in the September 2013 modelling that considered the potential impact of a capacity restriction along Leckhampton Lane.

2.8 The results of these model runs are reported in the Atkins Technical Note TN06, provided at Attachment 2.

2.9 TN06 provides a summary of the four scenarios modelled in the September 2013 modelling. These were:

• Scenario 1: 2014 Base + All JCS development built out by then excluding Leckhampton;

• Scenario 2: 2014 Base + All JCS development built out by then including Leckhampton;

• Scenario 3: 2023 Base + All JCS development excluding Leckhampton; and • Scenario 4: 2023 Base + All JCS development including Leckhampton +

Capacity limit along Leckhampton Lane.

2.10 In this case the Leckhampton development refers to the area within the application boundary, which includes 650 houses. The ‘without Leckhampton’ scenarios include the remaining 550 houses from the Illustrative Masterplan area.

2.11 No further modelling was required for the 2023 Base + All JCS development including Leckhampton because this scenario was included in the September 2012 modelling and was unchanged.

Peter Evans

Partnership


3.0 APPLICATION OF MODEL RESULTS

3.1 The Saturn model results reported in TN05 were utilised for the Transport Assessment September 2013. A comparison of flows with and without 1,200 dwellings and a mix of non-residential uses at the proposed Leckhampton development was considered and local junctions assessed on this basis.

3.2 The Supplementary Traffic Note January 2014 utilised the traffic flows reported in TN06 and in comparison with those reported in TN05, to consider the effect of a smaller scale of residential development (650 dwellings). The further scenario of a traffic constraint on Leckhampton Lane, as reported in TN06, was also provided in the January 2014 Traffic Note as a sensitivity test.

3.3 The Paramics modelling undertaken of the Highways Agency network, of relevance to the application, utilised the results in both TN05 and TN06.

Attachment 1 – Atkins Technical NoteTN05 Attachment 2 – Atkins Technical NoteTN06

TN05_Leckhampton

Technical note TN_05

Project: Leckhampton II Tests To: GCC/GH

Subject: 2023 CSV Forecast without Leckhampton II

From: Ashish Chadha/James Lindsay

Date: 2 Apr 2013 cc:

1.1. Background

ATKINS and Gloucestershire County Council (GCC) were requested by Peter Evans Partnership (PEP) on behalf of their client to undertake traffic forecasting and testing of the proposed Leckhampton II development.

ATKINS had earlier developed a 2008 base year validated SATURN traffic model of Central Severn Vale (CSV) region for GCC. This validated model was used to develop an updated 2023 base and three other forecast year traffic modelling scenarios as request by PEP below:

1. 2023 Base

2. 2023 Base + Leckhampton only

3. 2023 Base + All Development including Leckhampton

4. 2023 Base + All Development excluding Leckhampton

The model area covers Gloucester, Cheltenham and Tewkesbury in simulation and rest of the UK in buffer. The core study area is presented in figure 1 below. CSV model is strategic in nature and Leckhampton lies on the outskirts of Cheltenham town with only major roads being modelled in that area.

Figure 1. Study Area

Key

Model area

Leckhampton Development

TN05_Leckhampton

Technical note TN_05 1.2. Forecasting Methodology

The forecasting approach is summarised in figure 2. The approach had two streams to achieve 2023 forecasts of Leckhampton development i.e, network development and matrix development.

Figure 2. Forecasting Methodology

After initial review of the 2008 base year model PEP suggested that Kidnapper’s Ln and Farm Lane should be included in the model before forecasting. Thus these links were added to the base year and the model was recalibrated in the local area to represent the base year condition before undertaking forecasting.

Network development included:

Adding Kidnappers Ln/ Farm Ln roads to the 2008 base model

Adding 2023 network changes as per JCS modelling done earlier for GCC

Updating the generalised cost coefficients for 2023 forecast years As requested by PEP, traffic growth within the study area was taken from the supplied development trip ends. The total traffic growth within the internal study area was not constrained to TEMPRO, but growth in external area was derived from, and constrained to TEMPRO for cars and NTM for LGVs/HGVs.

Matrix development included:

Applying development trip ends to the base year car trip matrix

Applying TEMPRO growth factors to the external car trips

Applying NTM growth factors to LGV/HGV trips

Furnessing base year matrix to produce forecast

1.3. Scenario 1

This test scenario includes all the agreed and committed developments as described in the briefing note ‘2186 12.10.11 CSV Model Briefing Note Final with Atts.pdf’ and spreadsheet ‘JBB7795.Leckhampton.Spreadsheets.Housingtrajectories.06.09.12.V5.FinalDraft.xlsx’. The exceptions are the strategic JCS sites and Leckhampton development which are not modelled in this scenario.

Base Car Matrix Base LGV/HGV Matrix

Internal Trip Ends External Trip Ends

Development Growth

TEMPRO Growth

NTM Growth

Internal/External Trip Ends

2023 Highway Forecast Matrix

Base Highway Network

Kidnappers Ln/Farm Ln Network addition

2023 committed plus Leckhampton Scheme

2023 Highway Forecast Network

TN05_Leckhampton

Technical note TN_05

During the course of model development, ATKINS was informed that ‘Tewkesbury Rural’ allocations are part of Homelands I, Homelands II & Cleevelands development and there is no requirement to model it separately. A list of committed and completed sites including ‘Tewkesbury Rural’ as described above have been provided by GCC for the 2023 forecast year.

Networks from 2021 Joint Core Strategy (JCS) forecasts were used to develop the 2023 networks. After an initial assignment, these networks were further enhanced to ensure traffic generated by the new developments could be loaded on the network. This involved increasing capacity of selected junctions connected to small number of forecast site zone connectors. This approach is consistent across all the modelled scenarios presented in this report.

1.3.1. Results

Demand Forecast

The forecasting methodology, as agreed with GCC for 2021 JCS forecast was adopted for developing the 2023 AM and PM peak hour demand matrices. The base year 2008 demand was forecast to 2023. Table1 compares the growth of trips between 2008 base year and 2023 forecast year for the five user classes in the model. Overall an AM peak growth of 17% is projected between 2008 and 2023. Growth in the PM is slightly higher at 19%. Table 2 presents expected growth in trip ends due to developments for scenario 1.

Table 1. Growth in demand between 2008 and 2023 - scenario 1 (pcu/hr)

User Class

Morning Peak Evening Peak

Base 2023 % increase Base 2023 % increase

UC1 – Work 6627 7740 17% 6277 7223 15%

UC2 - Commute 29409 34973 19% 25311 31252 23%

UC3 – Others 22412 25144 12% 25773 29158 13%

UC4 – LGV 5046 6549 30% 3931 5206 32%

UC5 – HGV 4823 5594 16% 3534 4131 17%

All UC 68317 80000 17% 64825 76969 19%

Table 2. Total Development Tripends - scenario 1 (pcu/hr)


Origin Destination Origin Destination

Total 7,965 9,993 12,181 9,577

Global Network Statistics

The highway assignment results for base and forecast year for each time period vary in terms of the level of congestion, delay and overall journey time in and around the CSV area. Table 3 compares attributes in the base year and forecast for key global statistics, and each attribute is explained below.

Transient Queues (in PCU hours) – For example, at traffic signals the transient queue corresponds to the queue that develops during the red phase and then dissipates during the subsequent green phase.

TN05_Leckhampton

Technical note TN_05 Over-Capacity Queues (in PCU hours) – These occur only for turning movements in excess of capacity

where a permanent queue builds up which is unable to clear within the modelled period

Link Cruise Time (in PCU hours) – This is the time spent travelling on links within the model, as distinct from time spent in queues at junctions.

Total Travel Time (in PCU hours) – This is the sum of Transient Queue time, Over-Capacity Queue time and Link Cruise time.

Total Distance (in km) – This is the total distance travelled by all vehicles in the network.

Average Speed (in kph) – This is the average speed of vehicles in the network. (It is simply the Total Distance divided by the Total Travel Time).

Average Trip Time (in hours) – This is the average length of time taken for each trip. (It is calculated as the Total Travel Time divided by the number of trips.)

Average Trip Distance (in km) – This is the average distance covered by each trip. (It is calculated as the Total Distance divided by the number of trips.)

Table 3 clearly shows that as demand increases between the 2008 base to the forecast year, the level of congestion and delay increases as expected. This is reflected in the increase of the Total Travel Time, Transient and Over-Capacity queues, along with the decrease in Average Speed across the network. There is a substantial increase in the over capacity queues that reflects higher level of congestion in forecast years. It is noted from the last column in the table 3 that the deterioration greatly exceeds overall growth in demand of around 17% in the AM and 19% in PM.

Table 3. Summary statistics for base and forecast models - scenario 1

Indicator Time Period 2008 2023 Increase 08-23

Transient Queues (PCU hrs) AM 3,199 4,403 38%

PM 3,151 4,950 57%

Over-Capacity Queues (PCU hrs) AM 362 858 137%

PM 151 1,137 651%

Link Cruise Time (PCU hrs) AM 12,423 15,428 24%

PM 12,236 15,301 25%

Total Travel Time (PCU hrs) AM 15,984 20,689 29%

PM 15,538 21,388 38%

Total Distance (km) AM 9,10,459 10,81,820 19%

PM 8,96,397 10,70,154 19%

Average Speed (kph) AM 57 52 -8%

PM 58 50 -13%

Average Trip Time (hrs) AM 0.23 0.26 11%

PM 0.24 0.28 16%

Average Trip Distance (km) AM 13.33 13.55 2%

PM 13.85 13.93 1%

TN05_Leckhampton

Technical note TN_05 1.4. Scenario 2

Scenario 2 test includes all the committed developments provided by PEP up to 2023 including Leckhampton but excluding the strategic Joint Core Strategy (JCS) sites. This test provides a backdrop to compare and assess the quantum of development that can occupy the Leckhampton site without causing undue traffic problems in its vicinity, provided JCS doesn’t go forward but rest of the committed schemes build as per schedule.

As confirmed by PEP, Leckhampton II includes development Farm Lane/Kidnappers Lane site in addition to Leckhampton site. Thus out of total 1200 dwelling units proposed, 353 units have been allocated to existing zone 305 to represent Farm Lane development site and rest to zone 918 representing the Leckhampton site. Trips ends for Leckhampton residential development have been taken from the briefing note ‘2186 12.10.11 CSV Model Briefing Note Final with Atts.pdf’ and distributed on a pro rata basis depending upon the split in housing between Farm Lane and Leckhampton development.

Traffic distribution for the new Leckhampton zone was assumed to follow a similar pattern to the neighbouring existing zones of similar landuse. This principle was applied to all the new development trips across all user classes except for inbound commute trips to Leckhampton development, which uses the distribution from Journey to Work (JTW) data provided by PEP. As JTW data is at ward level therefore the distribution for this user class could only be replicated at ward level. The distribution within each ward follows the relative attractiveness of the zones in the 2008 base year model.

1.4.1. Results

Demand Forecast

Table 4 compares the growth of trips between 2008 base year and 2023 forecast year for the five user classes. Overall an AM peak growth of 18% is projected between 2008 and 2023. Growth in the PM is slightly higher at 19%. Table 5 presents expected growth in trip ends due to developments for scenario 2.

Table 4. Growth in demand between 2008 and 2023 scenario 2 (pcu/hr)

User Class



UC1 - Work 6627 7797 18% 6277 7263 16%

UC2 - Commute 29409 35296 20% 25311 31525 25%

UC3 - Others 22412 25257 13% 25773 29316 14%

UC4 - LGV 5046 6550 30% 3931 5206 32%

UC5 - HGV 4823 5600 16% 3534 4137 17%

All UC 68317 80501 18% 64825 77446 19%

Table 5. Total Development Trip ends - scenario 2 (pcu/hr)



Total 8,466 10,295 12,557 10,054

TN05_Leckhampton

Technical note TN_05 Global Network Statistics

The results for base and forecast year for each time period vary in terms of the level of congestion, delay and overall journey time in and around the CSV area. Table 6 compares attributes in the base year and forecast for key global statistics.

As expected, table 6 clearly shows that as demand increases between the 2008 base to the forecast year, the level of congestion and delay also increases. There is a substantial increase in the over capacity queues that reflects higher level of congestion in forecast years. It is noted that the deterioration in network performance greatly exceeds overall growth in demand of around 18%.

Table 6. Summary statistics for base and forecast models – scenario 2



PM 3,151 5,013 59%

Over-Capacity Queues (PCU hrs) AM 362 884 144%

PM 151 1,196 690%


PM 12,236 15,410 26%


PM 15,538 21,618 39%


PM 8,96,397 10,76,016 20%


PM 58 50 -14%


PM 0.24 0.28 17%


PM 13.85 13.92 1%

1.5. Scenario 3

This test scenario includes all the agreed and committed developments as described in the briefing note ‘2186 12.10.11 CSV Model Briefing Note Final with Atts.pdf’ and spreadsheet ‘JBB7795.Leckhampton.Spreadsheets.Housingtrajectories.06.09.12.V5.FinalDraft.xlsx’

Leckhampton development is included in scenario 3 and network updates are same as scenario 2. Farm Lane/Kidnappers Lane site is considered as a part of the proposed 1200 houses for Leckhampton development and trips are distributed accordingly as described previously for scenario 2.

TN05_Leckhampton

Technical note TN_05 1.5.1. Results

Demand Forecast

Table 7 compares the growth of trips between 2008 base year and 2023 forecast year Scenario 3 for the five user classes. As shown in table 8, overall an AM peak growth of 22% is projected between 2008 and 2023. Table 8 presents expected growth in trip ends due to developments for scenario 3.


User Class



UC1 - Work 6627 8145 23% 6277 7509 20%

UC2 - Commute 29409 37265 27% 25311 33229 31%

UC3 - Others 22412 25917 16% 25773 30298 18%

UC4 - LGV 5046 6587 31% 3931 5225 33%

UC5 - HGV 4823 5645 17% 3534 4178 18%

All UC 68317 83559 22% 64825 80440 24%

Table 8. Total Development Trip ends (pcu/hr)



Total 11,552 12,159 14,910 13,051


Table 9 compares attributes in the base year and forecast for key global statistics. The results for base and forecast year for each time period vary in terms of the level of congestion, delay and overall journey time in and around the CSV area.

There is a substantial increase in the over capacity queues that reflects higher level of congestion in forecast years. It is noted that the deterioration in network performance greatly exceeds overall growth in demand which is around 23%

Table 9. Summary statistics for base and Scenario-3 forecast models



PM 3,151 5,471 74%

Over-Capacity Queues (PCU hrs) AM 362 1,121 210%

PM 151 1,878 1141%


PM 12,236 15,984 31%


TN05_Leckhampton

Technical note TN_05 PM 15,538 23,334 50%


PM 8,96,397 11,07,343 24%


PM 58 48 -18%


PM 0.24 0.29 21%


PM 13.85 13.79 0%

1.6. Scenario 4

This test scenarios includes all the agreed and committed developments as described in the briefing note ‘2186 12.10.11 CSV Model Briefing Note Final with Atts.pdf’ and spreadsheet ‘JBB7795.Leckhampton.Spreadsheets.Housingtrajectories.06.09.12.V5.FinalDraft.xlsx’ except for Leckhampton development. Scenario 4 is essentially scenario 3 without Leckhampton development.

1.6.1. Results

Demand Forecast

Table10 compares the growth of trips between 2008 base year and 2023 forecast year for the five user classes. Table 11 presents expected growth in trip ends due to developments for scenario 4.


User Class



UC1 - Work 6627 8088 22% 6277 7470 19%

UC2 - Commute 29409 36942 26% 25311 32956 30%

UC3 - Others 22412 25804 15% 25773 30140 17%

UC4 - LGV 5046 6585 31% 3931 5225 33%

UC5 - HGV 4823 5639 17% 3534 4172 18%

All UC 68317 83058 22% 64825 79963 23%

Table 11. Total Development Tripends (pcu/hr)



Total 11,051 11,857 14,534 12,574

TN05_Leckhampton

Technical note TN_05 Global Network Statistics

Table 12 shows that as demand increases between the 2008 base to the Scenario 4 forecast year, the level of congestion and delay increases as expected. There is a substantial increase in the over capacity queues that reflects higher level of congestion in forecast years. It is noted from the last column in the table 12 that the deterioration greatly exceeds overall growth in demand of around 22%

Table 12. Summary statistics for base and Scenario 4 forecast models



PM 3,151 5,375 71%


PM 151 1,757 1064%


PM 12,236 15,870 30%


PM 15,538 23,002 48%

Total Distance (km) AM 910,459 1,110,504 22%

PM 896,397 1,101,191 23%


PM 58 48 -17%

Average Trip Time (PCU hrs) AM 0.23 0.26 13%

PM 0.24 0.29 21%


PM 13.85 13.80 0%

1.7. Scenario Comparison

As requested by PEP following four scenario differences have been created and presented in figure 3 onwards showing Flow differences, Delays differences and V/C differences for links/nodes. Below is a brief summary of plots where the results are not obvious and needs further explanation.

a) Figure 4 shows flow difference between 2023 Scenario 1 and 2008 Base. Traffic at Andover Rd/ Lansdowne Rd junction seems to be less in forecast. This is due to this junction working at capacity in the 2008 base. With increased demand the junction is getting congested and some of the trips are getting rerouted to adjacent roads. Also Shurdington Rd between Up Hatherley Way and Leckhampton Ln seems to have less flow in Scenario 1. Investigation revealed that there are increased delays at Shurdington Rd/Leckhampton Ln junction and as a result some of the traffic which was earlier using Shurdington Rd to reach Cheltenham is using alternate routes via Up Hatherley Way and Hatherley Rd joining A46 Shurdington Rd North of Up Hatherley Junction.

b) Figure 11 &12, represents flow difference between scenario 2 and scenario 1. As scenario 2 has extra Leckhampton development traffic, one would expect this scenario to have more traffic in the vicinity especially around Shurdington Rd. But figures show that there is decrease in traffic mainly between the eastern access of the development and Up Hatherley Way. This is attributed to the fact

TN05_Leckhampton

Technical note TN_05 that some of the through traffic diverts to other roads as development traffic loads on to the network. As development has two accesses so eastbound trips loads from east and westbound trips loads from west, thereby the absolute flow between the east and west accesses being lower than in scenario 1. Overall there is very little difference in throughput of the traffic as we move slightly away from the development on A46.

c) In Figures 12 &14, there is some flow difference around Andover Rd/ Lansdowne Rd junction which is not expected and can be attributed to the reason as described in figure 4 explanations.

TN05_Leckhampton

2023 Scenario 1 – 2008 Base

Figure 3. 2023 Scenario 1 – 2008 Base year AM flow difference

TN05_Leckhampton

Figure 4. 2023 Scenario 1 – 2008 Base year PM flow difference

TN05_Leckhampton

Figure 5. 2023 Scenario 1 – 2008 Base year AM Delay difference

TN05_Leckhampton

Figure 6. 2023 Scenario 1 – 2008 Base year PM Delay difference

TN05_Leckhampton

Figure 7. 2023 Scenario 1 – 2008 Base year AM V/C difference

TN05_Leckhampton

Figure 8. 2023 Scenario 1 – 2008 Base year PM V/C difference

TN05_Leckhampton

Figure 9. 2023 Scenario 1 – 2008 Base year AM V/C difference (Nodes)

TN05_Leckhampton

Figure 10. 2023 Scenario 1 – 2008 Base year PM V/C difference (Nodes)

TN05_Leckhampton

2023 Scenario 2 – Scenario 1

Figure 11. 2023 Scenario 2 – Scenario 1 AM flow difference

TN05_Leckhampton

Figure 12. 2023 Scenario 2 – Scenario 1 PM flow difference

TN05_Leckhampton

Figure 13. 2023 Scenario 2 – Scenario 1 AM Delay difference

TN05_Leckhampton

Figure 14. 2023 Scenario 2 – Scenario 1 PM Delay difference

TN05_Leckhampton

Figure 15. 2023 Scenario 2 – Scenario 1 AM V/C difference

TN05_Leckhampton

Figure 16. 2023 Scenario 2 – Scenario 1 PM V/C difference

TN05_Leckhampton

Figure 17. 2023 Scenario 2 – Scenario 1 AM V/C difference (Nodes)

TN05_Leckhampton

Figure 18. 2023 Scenario 2 – Scenario 1 PM V/C difference (Nodes)

TN05_Leckhampton



TN06_Leckhampton II Tests_v3

Technical Note (TN06)

Project: Leckhampton II Tests To: GCC/GH

Subject: 2014/23 Leckhampton II Tests From: Ashish Chadha/Anan Allos

Date: 4 March 2014 cc:

1.1. Background

ATKINS and Gloucestershire County Council (GCC) were requested by Peter Evans Partnership (PEP) on behalf of their client to undertake traffic forecasting and testing of the proposed Leckhampton II development. This work is in continuation of the Leckhampton development testing previously undertaken by ATKINS on behalf of PEP in early 2013 and presented in Technical Note TN_05 dated 2nd, April 2013.

ATKINS had previously developed a 2008 base year validated SATURN traffic model of the Central Severn Vale (CSV) area for GCC. This validated model was used to develop the following four traffic modelling scenarios for 2014 and 2023 as request by PEP:

1. Scenario 1: 2014 Base + Joint Core Strategy (JCS) Development built out by 2014 (in line with the housing trajectories spreadsheet provided by PEP Consultants), WITHOUT the Leckhampton development

2. Scenario 2: 2014 Base + JCS Development built out by 2014 (in line with the housing trajectories spreadsheet provided by PEP Consultants), WITH the Leckhampton development

3. Scenario 3: 2023 Base + JCS Development built out by 2023 (in line with the housing trajectories spreadsheet provided by PEP Consultants), WITHOUT the Leckhampton development; and

4. Scenario 4: Sensitivity test ‘2023 Base + JCS Development built out by 2023 WITH the Leckhampton development’, testing a capacity limit of 150 PCUs’ (passenger carrying units) per hour on Leckhampton Lane.

The model includes Gloucester, Cheltenham and Tewkesbury as part of the core simulation area, with the rest of the UK modelled as buffer network. The core study area is presented in Figure 1 below. It should be noted that the CSV model is strategic in nature and that the Leckhampton area of interest lies on the outskirts of the Cheltenham urban area with only the major roads being modelled in that area.



Figure 1. Study Area

1.2. Forecasting Methodology

The forecasting approach is summarised in Figure 2. The approach utilises two streams (network development and matrix development) to develop year 2014/2023 forecasts for the study area with the proposed Leckhampton development.

Figure 2. Forecasting Methodology

Base Car Matrix Base LGV & HGV Matrix

Internal Trip Ends External Trip Ends

Development Growth

TEMPRO Growth

NTM Growth

Internal/External Trip Ends

2014 & 2023 Highway Forecast Matrix

Base Highway Network

Network Update

2014 & 2023 Committed + Leckhampton Scheme

2014 & 2023 Highway Forecast Network

Key

Model area

Leckhampton Development



Based on a review of the earlier Technical Note TN 05 for the Leckhampton development - as referred to earlier in section 1.1, PEP requested the following assumptions to be adopted in developing the new scenarios for modelling.

1) The Leckhampton development to include only 650 houses, 4,500 sq m Employment (B1), 500 sq m Retail and 300 sq m GP Surgery (model zone 918)

2) The development at Farm Lane (c.350 houses, in model zone 305) and the development on the Council land (c. 200 houses, in model zone 936) to be included as part of the ‘Base’, rather than as part of the overall Leckhampton development.

3) The network and matrix assumptions to stay the similar (as in the earlier April 2013 assessment, but with the new trip ends), with the exception of the inclusion of the 550 houses at Farm Lane and on the Council land as part of the base.

Network development included:

The addition of new model zone 936, representing the Council Land, to the 2008 base model.

The development of the 2014 network from the 2008 base in line with the earlier JCS development network changes incorporated for the 2023 model runs.

Updating the generalised cost coefficients for the 2014 forecast years. As requested by PEP, traffic growth within the study area was obtained from the development trip ends provided in the PEP Technical Note ‘2186 13.09.26 CSV Model Briefing Note - September 2013 Final with atts.pdf’, as previously agreed with GCC officers . The total traffic growth within the internal study area (Gloucester, Cheltenham & Tewkesbury) was not constrained to TEMPRO. However, growth in the external areas was derived from, and constrained to TEMPRO and NTM for cars and LGVs/HGVs, respectively.

Matrix development included:

Applying the agreed development trip ends to the base year car trip matrix

Applying TEMPRO growth factors to the external car trips.

Applying NTM growth factors to LGV/HGV trips.

Furnessing the base year trip matrix to develop forecast trip matrices.

1.3. Scenario 1

Base + JCS Development built out by 2014, WITHOUT the Leckhampton development

Scenario 1 includes all committed developments up to 2014, based on information obtained from PEP/Skanska. It also includes the strategic Joint Core Strategy (JCS) sites but excludes the specific Leckhampton development under review. Scenario 1 therefore provides a benchmark to compare and assess the quantum of development that can occupy the Leckhampton site without causing undue traffic problems in its vicinity, assuming timely implementation of all committed highway schemes considered under Scenario 1.

As confirmed by PEP, the proposed Scenario 1 test excludes the Leckhampton development but assumes development of the Farm Lane/Kidnappers’ Lane site and the nearby Council Land as part of the base. Therefore 350 dwelling units were allocated to the Farm Lane development site (existing zone 305) and 200 dwelling units were allocated to the Council Land (zone 936). The trip ends for the proposed Leckhampton residential development were taken from the PEP briefing note ‘2186 13.09.26 CSV Model Briefing Note -


Technical Note (TN06) September 2013 Final with atts.pdf’ and distributed using the same methodology agreed for the earlier April 2013 Leckhampton modelling work.

Traffic distribution for the new model zones was assumed to follow a pattern similar to neighbouring existing zones with similar land uses.

The ‘Tewkesbury Rural’ allocations were considered to include the Homelands I, Homelands II & Cleevelands developments at Bishop’s Cleeve and hence to avoid double counting were not modelled separately.

A list of all the committed and completed development sites, including ‘Tewkesbury Rural’ as described above, were provided by GCC for the 2014 forecast year.

2008 Base year networks from the CSV model were used to develop the 2014 networks. In line with the earlier April 2013 modelling work, the networks were further enhanced to ensure that traffic generated by the new developments was able to load on to the network, which involved increasing the capacity of selected junctions connected to a small number of future zone connectors. This approach was applied to all the modelled scenarios presented in this report.

1.3.1. Results

Demand Forecasts

The forecasting method used for developing the 2014 AM and PM peak hour demand matrices was similar to that adopted to develop the 2023 Leckhampton forecast carried out earlier. The base year 2008 trip demand was projected to year 2014. Table 1 summarises the growth in trips between the 2008 base year and 2014 Scenario 1 for the five user classes in the model. In summary, the AM and PM peak hour growth rates between 2008 and 2014 were 9% and 10%, respectively.

Table 1. Growth in Demand between 2008 Base and 2014 Scenario 1 (pcu/hr)

User Class AM Peak PM Peak

Base 2014 Percent Change Base 2014 Percent Change

UC1 – Work 6,627 7,192 9% 6,277 6,760 8%

UC2 - Commute 29,409 32,514 11% 25,311 28,589 13%

UC3 – Other 22,412 23,818 6% 25,773 27,671 7%

UC4 – LGV 5,046 5,594 11% 3,931 4,418 12%

UC5 – HGV 4,823 5,259 9% 3,534 3,874 10%

Total 68,317 74,376 9% 64,825 71,312 10%

Table 2 below shows the expected growth in trips due to all committed and completed developments assumed as part of Scenario 1, including JCS developments .

Table 2. Total Development Trips - Scenario 1 (pcu/hr)

AM Peak PM Peak


Total Trips 4,764 4,283 5,881 5,710


The highway assignment results for the 2008 Base and Scenario 1 for each time period vary in terms of the level of congestion, delay and overall journey time in and around the CSV area. Table 3 provides a comparative summary based on the following global performance measures:



Transient Queues (in PCU hours) – For example, at traffic signals the transient queue corresponds to the queue that develops during the red phase and then dissipates during the subsequent green phase.

Over-Capacity Queues (in PCU hours) – These occur only for turning movements in excess of capacity where a permanent queue builds up which is unable to clear within the modelled period

Link Cruise Time (in PCU hours) – This is the time spent travelling on links within the model, as distinct from time spent in queues at junctions.

Total Travel Time (in PCU hours) – This is the sum of Transient Queue time, Over-Capacity Queue time and Link Cruise time.

Total Distance (in km) – This is the total distance travelled by all vehicles in the network.

Average Speed (in kph) – This is the average speed of vehicles in the network. (It is simply the Total Distance divided by the Total Travel Time).

Average Trip Time (in hours) – This is the average length of time taken for each trip. (It is calculated as the Total Travel Time divided by the number of trips.)

Average Trip Distance (in km) – This is the average distance covered by each trip. (It is calculated as the Total Distance divided by the number of trips.)

Table 3 shows that the change in demand between the 2008 Base and 2014 Scenario 1 results in an increase in congestion and delays. This is reflected in the increase of the Total Travel Time, Transient and Over-Capacity queues, along with a decrease in Average Speed across the network. It should be noted that there is a substantial increase in the over-capacity queues (+186% and +687% for the AM and PM peak hours respectively) indicating that the level of congestion is expected to increase considerably under Scenario 1. It is noted that the deterioration in network performance greatly exceeds overall growth in demand which is around 10%, as shown in Table 1

Table 3. .Summary Statistics for 2008 Base and Scenario 1 Models -

Performance Measure Time Period 2008 2014 Percent Change


PM 3,151 3,831 22%


PM 151 1,189 687%


PM 12,236 13,538 11%


PM 15,538 18,558 19%

Total Distance (km) AM 910,459 977,095 7%

PM 896,397 972,776 9%


PM 58 52 -10%


PM 0.24 0.26 9%

Average Trip Distance (km) AM 13.33 13.16 -1%

PM 13.85 13.67 -1%



1.4. Scenario 2

Base + JCS Development built out by 2014, WITH the Leckhampton development

This test scenario includes all the agreed and committed developments for Scenario 1 as described in section 1.3, plus the Leckhampton development having 650 dwelling units (allocated to model zone 918) along with supportive Employment, Retail and GP Surgery land uses (refer section 1.2).

Traffic distribution for the new zones was assumed to follow a pattern similar to neighbouring existing zones with similar land uses. This principle was applied to all the new development trips across all user classes except for inbound commute trips to the proposed Leckhampton employment element of the development. Instead, these inbound commute trips were based on Journey to Work (JTW) data provided by PEP. Since the JTW data is at ward level, the distribution for the ‘car commute’ user class was replicated at the ward level. The distribution within each ward follows the relative attractiveness of the zones in the 2008 base year model.

1.4.1. Results

Demand Forecasts

Table 4 summarises the growth in trips between the 2008 Base year and 2014 Scenario 2 models for the five user classes. The AM and PM peak hour growth rates between 2008 and 2014 were 9% and 10%, respectively.


User Class AM Peak PM Peak

Base 2014 Percent Change Base 2014 Percent Change UC1 - Work 6,627 7,223 9% 6,277 6,781 8%

UC2 - Commute 29,409 32,689 11% 25,311 28,737 14%

UC3 - Other 22,412 23,879 7% 25,773 27,756 8%

UC4 - LGV 5,046 5,595 11% 3,931 4,418 12%

UC5 - HGV 4,823 5,263 9% 3,534 3,877 10%

Total 68,317 74,648 9% 64,825 71,570 10%

Table 5 presents the expected growth in trips due to all completed and committed developments, as well as JCS developments and the proposed Leckhampton development assumed as part of Scenario 2.

Table 5. Total Development Trips - Scenario 2 (pcu/hr)

AM Peak PM Peak


Total Trips 5,195 4,502 6,172 6,097



Technical Note (TN06) The highway assignment results for the 2008 Base and Scenario 2 for each time period vary in terms of the level of congestion, delay and overall journey time in and around the CSV area, with Table 6 providing a comparative summary based on key performance measures.

Table 6 shows that the change in demand between the 2008 Base and 2014 Scenario 2 results in increases in congestion and delays. It should be noted that there is a substantial increase in the over-capacity queues indicating that the level of congestion is expected to increase considerably under Scenario 2. It is noted that the deterioration in network performance greatly exceeds overall growth in demand which is around 10%, as shown in Table 4, and which is similar to the growth in demand for Scenario 1.

Table 6. Summary Statistics for 2008 Base and Scenario 2 Models



PM 3,151 3,852 22%


PM 151 1,302 763%


PM 12,236 13,571 11%


PM 15,538 18,725 21%

Total Distance (km) AM 910,459 978,931 8%

PM 896,397 974,431 9%


PM 58 52 -10%


PM 0.24 0.26 9%


PM 13.85 13.64 -2%

1.5. Scenario 3

2023 Base + JCS Development built out by 2023, WITHOUT the Leckhampton development

As in Scenario 1 for 2014, the proposed Scenario 3 for 2023 test excludes the Leckhampton development but includes the Farm Lane/Kidnappers’ Lane development site and the houses on the Council Land as part of the ‘base’. Therefore 350 dwelling units were allocated to the Farm Lane development site (existing zone 305) and 200 dwelling units to the Council Land (zone 936). Trips ends for the proposed Leckhampton residential development were taken from the PEP briefing note ‘2186 13.09.26 CSV Model Briefing Note - September 2013 Final with atts.pdf’, and distributed using the methodology agreed for the earlier April 2013 Leckhampton work.

Traffic distribution for the zones containing the new developments was assumed to follow a pattern similar to neighbouring existing zones with similar land uses.

The ‘Tewkesbury Rural’ allocations were considered to include Homelands I, Homelands II & Cleevelands developments and hence, to avoid double counting, were not modelled separately. A list of the committed and completed sites including ‘Tewkesbury Rural’ as described above, were provided by GCC for the 2023 forecast year.


Technical Note (TN06) 2023 networks from the earlier April 2013 Leckhampton modelling exercise were used to develop the updated networks for this scenario, with the new zone 936 added and appropriate access provided.

Demand Forecasts


Table 7. Growth in Demand Between 2008 Base and 2023 Scenario 3 (pcu/hr)

User Class

AM Peak PM Peak


UC1 - Work 6,627 8,113 22% 6,277 7,487 19%

UC2 - Commute 29,409 37,085 26% 25,311 33,077 31%

UC3 - Other 22,412 25,854 15% 25,773 30,210 17%

UC4 - LGV 5,046 6,585 31% 3,931 5,225 33%

UC5 - HGV 4,823 5,642 17% 3,534 4,175 18%

Total 68,317 83,278 22% 64,825 80,174 24%

Table 8 shows the predicted growth in trips due to the committed and completed developments, the build out of the proposed JCS developments as assumed as part of Scenario 3.

Table 8. Total Development Trips – Scenario 3 (pcu/hr)

AM Peak PM Peak


Total 11,272 11,939 14,662 12,785


The comparison of the highway assignment results for the 2008 Base and 2023 Scenario 3 models for each time period vary in terms of the level of congestion, delay and overall journey time in and around the CSV area. Table 9 provides a comparative summary based on the key performance measures.

Table 9 shows that the change in demand between the 2008 Base and Scenario 3 would result in a substantial increase in the over-capacity queues leading to congestion and delays. It is noted that the deterioration in network performance greatly exceeds overall growth in demand which is around 23%.




PM 3,151 5,228 66%


PM 151 1,674 1009%


PM 12,236 15,518 27%



Technical Note (TN06) PM 15,538 22,421 44%


PM 896,397 1,076,776 20%


PM 58 48 -17%


PM 0.24 0.28 17%


PM 13.85 13.46 -3%

1.6. Scenario 4

2023 Base + JCS Development built out by 2023, WITH the Leckhampton development plus a capacity limit on Leckhampton Lane

The purpose of this Scenario is to provide a ‘sensitivity test’ to assess the effects of introducing a capacity restraint of 150 PCUs on Leckhampton Lane in both directions, on the section immediately east of the priority junction with the A46.

This test scenario includes all the agreed and committed developments as described in the PEP Briefing Note ‘2186 12.10.11 CSV Model Briefing Note Final with Atts.pdf’, and spreadsheet ‘JBB7795 Leckhampton.Spreadsheets.Housing Trajectories.06.09.12.V5.FinalDraft.xlsx.’ The Leckhampton development is included in scenario 4 and network updates are similar to those in scenario 3 described previously.

Traffic distribution for the new zones was assumed to follow a pattern similar to neighbouring existing zones with similar land uses. This principle was applied to all the new development trips across all user classes except for inbound commute trips to the proposed Leckhampton development, which were based on the Journey to Work (JTW) data provided by PEP. Since the JTW data is at ward level, the distribution for this user class was replicated at the ward level. The distribution within each ward follows the relative attractiveness of the zones in the 2008 base year model.

1.6.1. Results

Demand Forecasts



User Class

AM Peak PM Peak


UC1 – Work 6,627 8,145 23% 6,277 7,509 20%

UC2 – Commute 29,409 37,265 27% 25,311 33,229 31%

UC3 – Other 22,412 25,917 16% 25,773 30,298 18%

UC4 – LGV 5,046 6,587 31% 3,931 5,225 33%

UC5 – HGV 4,823 5,645 17% 3,534 4,178 18%


Technical Note (TN06) Total 68,317 83,559 22% 64,825 80,440 24%

Table 11 shows the expected growth in vehicle trips due to committed, completed and proposed JCS developments including the Leckhampton development, as assumed in Scenario 4

Table 11. Total Development Trips – Scenario 4 (pcu/hr)

AM Peak PM Peak


Total 11,552 12,159 14,910 13,051


The highway assignment results for the 2008 Base and 2023 Scenario 4 for each peak hour time period vary in terms of the level of congestion, delay and overall journey time in and around the CSV area, with Table 12 providing a comparative summary based on key performance measures.

Table 12 shows that the change in demand between the 2008 Base and Scenario 4 results in an increase in congestion and delays. It should be noted that there is a substantial increase in the over-capacity queues, indicating that the level of congestion is expected to increase considerably under Scenario 4. It is also noted that the deterioration in network performance greatly exceeds overall growth in demand which, from Table 10 above, is around 23% for either peak hour.




PM 3,151 5,320 69%


PM 151 1,750 1059%


PM 12,236 15,571 27%


PM 15,538 22,641 46%


PM 896,397 1,079,534 20%


PM 58 48 -18%

Average Trip Time (PCU hrs) AM 0.23 0.26 13%

PM 0.24 0.28 18%


PM 13.85 13.45 -3%


Technical Note (TN06) 1.7. Comparison of Scenario Results

The following set of Figures (3 to 18) provide a series of comparisons of Scenarios in the form of ‘flow difference plots’, differences in average vehicle delays and differences in Volume / Capacity (V/C) ratios for network links/nodes.

Two sets of network comparisons have been provided, with Figures 3 to 10 based on a comparison of Scenario 2 against Scenario 1, while Figures 11 to 18 summarise the differences between Scenario 4 and Scenario 3. In the subsequent flow difference plots, green depicts an increase in vehicle flows, and blue a decrease.

A brief summary of the key results of this comparative analysis is provided below:-

1. Figures 3 & 4 show the AM and PM peak hour ‘flow differences’ between Scenario 2 and Scenario1. for the 2014 year of opening, with and without the Leckhampton development in place. The results show that with the inclusion of the Leckhampton development there is some shift in modelled southbound traffic on to Up Hatherley Way away from Caernarvon Road & Woodlands Road. This could be attributed to the reduced travel time on the route due to the reconfiguration of key A46 junctions around the Leckhampton development. As expected, there is also increased vehicle flow in Scenario 2 on the A46 in the vicinity of the development site, due to the newly generated traffic.

2. Figures 5 & 6 show the differences in average vehicle delays for the AM and PM peaks, indicating minor increases in delay at the 2 Leckhampton site access junctions, as well as at the Charlton Lane / Old Bath Lane junction in the AM peak hour.

3. Figures 7& 8 provide a comparison of V/C link flow differences, showing the Charlton Lane / Old Bath Rd junction operating at capacity during the AM peak in Scenario1 (Figure 7), experiencing vehicle ‘blocking back in Scenario 2 resulting in a higher V/C ratio at the junction. Figures 9 & 10 show the differences in Junction V/C ratios which, as was the case in Figures 5 & 6, indicate significant increases at key junctions along the A46 Shurdington Road corridor adjacent the Leckhampton development site.

4. In the comparison of Scenario 4 against Scenario 3 for the 2023 future year, Figures 11 & 12 show the rerouting of traffic from Leckhampton Lane on to Shurdington Road. This is primarily due to the introduction of the capacity restriction on Leckhampton Lane (down to 150 PCUs per hour in Scenario 4). There is also a diversion of through traffic into the Up Hatherley area away from the A46 corridor. This is due to the Up Hatherley Way/ Shurdington Road and Woodlands Road/Shurdington Rd Junctions (Figure 13 & 14) experiencing congestion on account of the growth of traffic along with the Leckhampton development, together with the link capacity restriction on Leckhampton Lane.

5. Figures 15 & 16 show an increase in the V/C ratio for link capacity on Leckhampton Lane in Scenario 4 compared to Scenario 3, due to the capacity restriction at Leckhampton Lane. Increases in link capacity ‘ratios’ are also apparent on the A46 corridor approaching the Up Hatherley Way roundabout.

6. Consistent with the above, Figures 17 & 18 show increased V/C ratios for junctions along the A46 Shurdington Rd due to diversion of traffic from Leckhampton Lane because of the capacity restrictions. The Leckhampton Lane/Farm Lane junction experiences an increased V/C ratio up to 88 % in the AM for the eastbound movement towards Cheltenham. .There is also an increased V/C ratio for left turning traffic from Leckhampton Lane at the Leckhampton Lane/A46 junction. The Moorend Park Road junction with the A46 also experiences an increased V/C ratio (nearly 100% eastbound towards Cheltenham town centre in the AM peak) for nearly all the junction movements with the extra generated traffic and diverted flow on the A46.

7. Finally, the significant decrease in the V/C ratio at the Leckhampton Lane/Shurdington Road junction (as shown in Figure 18) is due to the fact that there is less turning traffic to / from the Leckhampton Lane side road which as a result, increases the ‘A46 straight ahead’ capacity for eastbound traffic towards Cheltenham town centre.

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