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DEVIZES S-PARAMICS TRAFFIC MODEL

2026 MODEL FORECASTING:CORE STRATEGY OPTION TESTINGDecember 2011

DEVIZES TRAFFIC MODEL 2026 MODEL FORECASTING: CORE STRATEGY OPTION TESTING

December 2011

G:\Workfiles\W423\REPORTS\W423-DOC01-Model Forecasting.doc

DOCUMENT CONTROL

Job No. W423

Name Date Initials

Prepared by J Alexander 23.12.2011

Checked by P Cogar (SIAS) 23.12.2011 PC

Issue Date Comments Approved

4 23.12.2011 Final

P J Tregear This document has been prepared for the exclusive use of the client in connection with the project and unless otherwise agreed in writing by PFA Consulting, no other party may copy, reproduce, make use of or rely upon the contents of this report other than for the purposes for which it was originally prepared and provided. Opinions and information provided in this document have been provided using due care and diligence. It should be noted and is expressly stated that no independent verification of any information supplied to PFA Consulting has been made. Warning: This document may contain coloured images which may not print satisfactorily in black and white. It may also contain images originally created at a size greater than A4 which may not print satisfactorily on small printers. If copying is authorised but difficulty is incurred in reproducing a paper copy of this document, or a scaled copy is required, please contact PFA Consulting. Authorisation for reproducing plans based upon Ordnance Survey information cannot be given.

DEVIZES TRAFFIC MODEL 2026 MODEL FORECASTING: CORE STRATEGY OPTION TESTING

December 2011


CONTENTS

PAGE NO.

1. INTRODUCTION ............................................................................................................. 1

2. FORECASTING METHODOLOGY ................................................................................... 2

3. TRAFFIC GROWTH .......................................................................................................... 4

4. FUTURE DEVELOPMENT ................................................................................................. 6

5. PEAK SPREADING ............................................................................................................ 9

6. MODELLED SCENARIOS ................................................................................................ 10

7. MODEL OUTPUTS ......................................................................................................... 12

FIGURES

Figure 1 Devizes Traffic Model Study Area Figure 2 Developments Included in 2026 Model Forecasting Figure 3 Modelled Link Flows – AM Peak Hour (08:00-09:00) Figure 4 Modelled Link Flows – PM Peak Hour (17:00-18:00) Figure 5 Local Areas Assessed for Air Quality APPENDICES

Appendix A Devizes S-Paramics Modelled Highway Network Appendix B TEMPRO/NTM Traffic Growth Calculations Appendix C Development Schedule for 2026 Model Forecast Scenarios Appendix D 2026 Devizes Traffic Model Zone Plan for 2026 Forecasting Appendix E Network Wide Average Journey Time Graphs Appendix F A361 ‘Through Traffic’ Average Journey Time Graphs

DEVIZES TRAFFIC MODEL 2026 MODEL FORECASTING: CORE STRATEGY OPTION TESTING Page 1 of 21

December 2011


1. INTRODUCTION 1.1. PFA Consulting was commissioned by Wiltshire Council to develop future year

traffic model forecasts using the Devizes S-Paramics micro-simulation traffic model to assess the traffic impacts on the highway network from additional transport demand in Devizes up to 2026.

1.2. The traffic modelling provides technical evidence to assist Wiltshire Council in

developing its Core Strategy as part of the Local Development Framework (LDF) process. The results from the traffic modelling will help guide the development of a transport strategy for Devizes which will support the formulation of the Core Strategy element of the LDF.

Background

1.3. A 2011 base year S-Paramics traffic model of Devizes has recently been developed which represents the existing traffic patterns and conditions on the local highway network in both the weekday AM peak period (07:00-10:00) and weekday PM peak period (16:00-19:00).

1.4. The validated 2011 base year traffic model provides the basis from which to

develop 2026 future year model forecasts to assess potential development options put forward by Wiltshire Council to meet the housing and employment requirements of Wiltshire’s Core Strategy.

1.5. Figure 1 identifies the Devizes traffic model study area with the S-Paramics

modelled highway network represented at Appendix A. Report Outline

1.6. This report details the methodology adopted in developing future year traffic model forecasts and presents the model outputs from a number of development scenarios tested.


December 2011


2. FORECASTING METHODOLOGY 2.1. The aim of the forecasting in the Devizes traffic model is to determine the

impact on the future transport network as a consequence of shifting patterns of demand over time from planned development and traffic growth.

2.2. The model forecasting has assumed an assessment year of 2026 which is

consistent with Wiltshire Council’s Core Strategy Plan Period. 2.3. The forecasting methodology has allowed for traffic growth, proposed

developments, peak spreading and changes to the highway network planned to come forward by 2026. A summary of the forecasting methodology is set out below.

2026 Matrix Development

‘Lights’ (cars & lgvs)

Split the 2011 ‘Lights’ matrix into two matrices; an ‘external’ matrix containing external to external trips only, and an ‘internal’ matrix which only contains trips with an origin and/or a destination in Devizes.

Take the 2011 ‘external matrix’ and growth trips by applying Wiltshire TEMPRO growth factors.

Take the 2011 ‘internal matrix’ and generate a future year 2026 ‘internal

matrix’ by “furnessing” to future year trip ends allowing for proposed development in Devizes and applying local Devizes TEMPRO growth factors to zones where appropriate (e.g. town centre car parks, retail stores, external zones).

Add the factored 2026 ‘external matrix’ to the factored 2026 ’internal matrix’

containing development trips.

‘Heavies’ (hgvs) Take the 2011 HGV matrix and growth trips to 2026 by applying National

Transport Model (NTM) growth factors from the Department for Transport (DfT) ‘Road Transport Forecasts 2009’ for the South-West Region.

2026 Network Development

Development of a 2026 forecast modelled highway network to include proposed highway improvements assumed to come forward by 2026. This includes the two pedestrian crossings on London Road and Windsor Drive, and the proposed relocation of the eastbound bus stop on Estcourt Street.

2026 Model Forecasts

2026 model forecasts were created for a number of development scenarios to assess the operation of the local highway network in Devizes. The 2026 demand profiles were adjusted using a ‘peak spreading’ procedure to reflect drivers retiming their journeys to avoid congestion.


December 2011


2011 Base Year Matrix (Lights) –

Internal Trips Only

2011 Base Year Matrix (Lights) -

External to External Trips

2011 Base Year Highway Network

2011 Base Year Matrix

Furness Matrix to 2026 zonal row and column

totals allowing for Development and applying TEMPRO

(Devizes) Local Growth Factors 2011-2026 where appropriate

Apply TEMPRO (Wiltshire)

Growth Factors 2011-2026

2026 Forecast Year Matrix

2026 Forecast Year Highway Network

Add proposed changes to

Highway Network

2026 Forecast Year Model

Model Outputs

2011 Base Year Matrix

(HGVs)

Apply NTM (South West) HGV Growth Factors 2011-

2026 for Principal

Roads

Micro-Time Period Choice “Peak Spreading”

2026 Model Forecasting Methodology


December 2011


3. TRAFFIC GROWTH 3.1. To represent the situation in the 2026 forecast year, traffic growth has been

applied to the 2011 base year trip matrices following guidance set out in the DfT Transport Analysis Guidance (TAG) Unit 3.15.2 ‘Use of TEMPRO data’, for highway only models, this ensures that the model forecasts benefits from nationally and locally derived growth projections in accordance with government guidance.

3.2. TEMPRO (Dataset version 6.2) was used to calculate growth factors for external

to external trips and for trips with an origin and/or a destination within Devizes.

External to External Traffic (Lights) 3.3. For the longer distance (external to external) through trips the car driver trip end

growth for the Wiltshire TEMPRO zone was derived for both the AM and PM peak periods.

3.4. Table 1 below shows the external to external growth factors 2011-2026 derived

from TEMPRO for both the AM and PM peak periods. Full details of the traffic growth calculations are included at Appendix B.

Table 1: External to External Traffic Growth Factors 2011–2026 (TEMPRO) Wiltshire TEMPRO Zone Growth Factor

AM Peak 1.117

PM Peak 1.128

3.5. The above growth factors derived from TEMPRO were applied to the 2011 base

year external to external matrices to produce 2026 external to external forecast matrices.

Internal Trips (Lights) 3.6. For the internal trips the car driver trip end growth for the local Devizes

TEMPRO zone was derived for both the AM and PM peak periods. 3.7. Table 2 below shows the internal growth factors 2011-2026 derived from

TEMPRO for both the AM and PM peak periods. Full details of the traffic growth calculations are included at Appendix B.

Table 2: Internal Traffic Growth Factors 2011–2026 (TEMPRO) Devizes TEMPRO Zone Growth Factor

AM Peak 1.048

PM Peak 1.057

3.8. Table 3 shows reduced traffic growth factors derived from the Devizes TEMPRO

zone using the ‘alternative planning data’ facility within the TEMPRO software which reflects only those committed housing developments in Devizes coming forward by 2026. Full details of the TEMPRO calculations are provided at Appendix B.


December 2011


Table 3: Internal Traffic Growth Factors ‘Committed Development Only’ 2011–2026 (TEMPRO) – Alternative Planning Data Assumptions Devizes TEMPRO Zone Growth Factor

(Committed Development only) AM Peak 1.021

PM Peak 1.030

3.9. The standard method of applying trip-end growth factors is by multiplying base

year trip matrix row and column totals by TEMPRO growth factors and then ‘furnessing’ the base matrix to these totals. However, to more accurately model the development likely to come forward in Devizes, the future year trip ends (row and column totals) were derived having regard to the scale and location of future development in Devizes (See Section 4), with TEMPRO growth factors only applied to non-development zones where appropriate.

3.10. As the ‘furness’ procedure only converges when row and column totals each

have the same number of trips, the two estimates of the total trips in the matrix (one from the rows, one from the columns) need to be reconciled. This was done by taking the average of the two estimates, and controlling both row and column totals to this total.

3.11. The trip end growth factors derived from TEMPRO were applied to the 2011

base year matrices using the ‘furness’ procedure described above to produce 2026 forecast matrices for internal trips.

HGV Growth 3.12. Growth factors for HGV’s were obtained from the ‘Road Transport Forecasts

2009’ document which is produced by the ITEA division of the DfT using the National Transport Model (NTM). The NTM provides growth factors at the regional level by road type for rigid and articulated HGV’s.

3.13. Table 4 details the HGV growth between 2011 and 2026 derived from the NTM

for the South West Region for Principal Roads, with full details provided at Appendix B.

Table 4: HGV Growth Factor 2011-2026 (NTM) South-West Region Principal Road Type Growth Factor

2011 to 2026 1.107

3.14. The HGV growth factors derived from NTM were applied to the 2011 base year

HGV matrices to produce 2026 HGV forecast matrices.


December 2011


4. FUTURE DEVELOPMENT 4.1. The TEMPRO guidance advises that where a development proposal is likely to

have a significant impact on demand for transport it should be explicitly modelled.

4.2. The Devizes traffic model forecasting has explicitly modelled all developments

in Devizes to ensure a robust and more accurate assessment of the impacts that the developments would have on the operation of the highway network.

Committed Development 4.3. Table 5 details existing committed developments (as of July 2011) in Devizes

which are assumed to be delivered by 2026. This includes the outstanding residential commitments at the former Spitalcroft allotments, Naughton Aveneue, Quakers Walk and Bureau West, together with the saved Kennet Local Plan employment allocation on Land at Nursteed Road. The commitments have also included the new two-form entry primary school at Quakers Walk which is due to open next year, and the new B&Q retail store off Hambleton Avenue which opened in the summer (the former FOCUS store was closed in the 2011 base model).

Table 5: Committed Development (as of July 2011)

Ref Sites Scale

Residential: 1 Former Spitalcroft Allotments 8 units

2 Land at Quakers Walk 87 units

3 Land at Naughton Avenue 7 units

4 Land at Bureau West 118 units

Employment:

5 Land at Nursteed Road (Saved Kennet District Plan allocation) 1.5 Hectares

Other:

6 Relocated St Peter' s School at Quakers Walk 300 pupils

7 B&Q Store, Hambleton Avenue 2,275 GFA

4.4. Figure 2 details the locations of each of the committed developments.

Core Strategy Potential Development Sites 4.5. Table 6 details those sites which Wiltshire Council considers could potentially

be developed within the Devizes urban area thorough its Core Strategy. 4.6. The sites represent a general distribution of development within Devizes’ current

limits of development. The residential sites were chosen from the published Strategic Housing Land Availability Assessment (SHLAA). The sites do not however have any status within the Core Strategy and their selection should not be read as implying development will be permitted. They were selected to test potential impact on the highway network of the housing proposals for Devizes in the emerging Wiltshire Core Strategy.


December 2011


4.7. In addition to the residential sites, 8.4 hectares of land between the A361 and Horton Road is assumed to come forward as a strategic employment site.

Table 6: Core Strategy Potential Development Sites

Ref Sites Scale

Residential:

8 Former Clinic, Green Lane 50 units

9 Garden Trading Estate 70 units

10 Land South of Parkfield 60 units

11 Football Club off Nursteed Road 100 units

12 Land off Hambleton Avenue 30 units

13 Land adjoining Lay Wood 100 units

14 Devizes Wharf 30 units

15 St Peters School Site 25 units

Employment:

16 Land between A361 and Horton Road 8.4 Hectares

4.8. The locations of the Core Strategy potential development sites in Devizes are

shown in Figure 2.

Additional Larger Peripheral Residential Sites 4.9. Table 7 details additional larger scale residential development in Devizes. The

sites were chosen from the SHLAA and to reflect where there is developer led interest for additional, long term, development in Devizes.

4.10. The sites were selected to test the potential impact of peripheral growth on the

highway network. However, not all options where there is developer interest for additional long term growth were tested.

4.11. The locations of the three larger scale residential sites are shown in Figure 2.

Table 7: Additional Larger Scale Residential Sites

Ref Sites Scale

Residential:

17 Land off the A342 south of Marshall Road 220 units

18 Land at Coate Bridge 400 units

19 Land to the North East of Roundway Park 400 units

Development Traffic Generation & Distribution 4.12. Traffic generation for the various developments detailed above was estimated

using trip rates derived from either locally observed data or the TRICS database. 4.13. The traffic generation calculations for both the AM peak (07:00-10:00) and PM

peak (16:00-19:00) time periods for each of the development sites, including the trip rates adopted, are set out in the table at Appendix C.


December 2011


4.14. The methodology adopted for the distribution of the development traffic was based on the distribution from existing zones (same land use and location) in the traffic model. Appendix C identifies those zones used for distributing the development traffic for each development site.

Forecast Zone Plan 4.15. The Devizes traffic model zone plan was refined to incorporate the proposed

development detailed above. Appendix D details the revised Devizes zone plan used for the traffic forecasting.


December 2011


5. PEAK SPREADING 5.1. Peak spreading is a behavioural response to congestion resulting from traffic

growth. It occurs when travellers choose to depart earlier or later than their preferred time of travel in order to reduce their travel time.

5.2. Peak spreading is caused by relatively small changes in departure time, which

are a response to the variation in travel times between origins and destinations. These variations are caused by the build-up and dispersal of queues at points in the network. This is a dynamic process, which is not possible to represent using standard assignment methods, which are time-aggregate.

5.3. Within a modelled time period, S-Paramics provides the ability to represent

demand variation through the use of release profiles based on 5-minute periods. These are applied in a flexible manner to groups of zones, individual zones, sector to sector movements, or specific origin/destination (OD) movements. The release profiles provide an ideal tool for modelling peak spreading.

5.4. The peak spreading methodology uses an incremental logit model of departure

time choice, where changes in travel time govern the spread of demand over the peak period. The incremental logit model is used to derive a new release profile by modifying a base year release profile with reference to the change in travel times between base and future years.

5.5. The peak spreading procedure outlined above has been applied to the Devizes

traffic model forecasting resulting in a revised set of demand release profiles for the 2026 model forecasts as a consequence of people retiming their journeys to avoid congestion. Not all of the profiles in the model have been subject to the peak spreading procedure, for example, the profiles for trips to/from schools in Devizes have been unaltered from the 2011 base year.


December 2011


6. MODELLED SCENARIOS

Modelled Scenarios 6.1. Table 8 sets out the scenarios which have been modelled using the Devizes

traffic model for both the AM and PM peak periods. Table 8: Modelled Scenarios

1 2011 Base Year

2 2026 Existing Commitment Only

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case)

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd

5 2026 Reference Case + Development on Land at Coate Bridge

6 2026 Reference Case + Development on Land north-east of Roundway Park

Trip Matrix Totals

6.2. The numbers of trips in the matrices for each of the modelled scenarios are shown in Table 9 and represented in the graphs below. The percentage growth in trips in the matrix for each of the 2026 scenarios is given in Table 10.

Table 9: Trip Matrix Totals

Scenario AM Peak (07:00-10:00) PM Peak

(16:00-19:00)

1 2011 Base Year 15,221 17,052

2 2026 Existing Commitment Only 15,981 17,946

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 16,644 18,738

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 16,870 19,029

5 2026 Reference Case + Development on Land at Coate Bridge 17,040 19,268

6 2026 Reference Case + Development on Land north-east of Roundway Park 17,040 19,268

Table 10: Trip Matrix Percentage Increase from 2011 Base Year

Scenario AM Peak (07:00-10:00) PM Peak

(16:00-19:00)

1 2011 Base Year - -

2 2026 Existing Commitment Only +5% +5.2%

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) +9.5% +9.9%

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd +10.8% +11.6%

5 2026 Reference Case + Development on Land at Coate Bridge +12.0% +13.0%

6 2026 Reference Case + Development on Land north-east of Roundway Park +12.0% +13.0%


December 2011



December 2011


7. MODEL OUTPUTS 7.1. This section of the report provides the outputs from the S-Paramics models for all

of the scenarios tested. The outputs represent an average from 5 separate seeded runs of the model for each scenario. Performing multiple runs and combining the data is statistically more robust than relying on a single run of the model.

7.2. To assess the relative performance of each of the scenarios the following model

outputs have been analysed:

Modelled Link Flows Network Wide Average Speed Network Wide Average Journey Time A361 ‘Through Traffic’ Average Journey Time Bus Journey Times Vehicle Emissions Modelled Link Flows

7.3. Figures 3 & 4 show two-way link traffic flows on key links in Devizes derived from the traffic model for each scenario for the weekday AM peak hour (08:00-09:00) and weekday PM peak hour (17:00-18:00) time periods.

7.4. The figures show some links experiencing little change in traffic flows in the

2026 forecast year, this is not unusual in congested urban networks where less traffic gets through as congestion increases. The effect of peak spreading also reduces the level of traffic during the peak hours with increased levels of congestion.

Network Wide Average Speed

7.5. Tables 11 & 12 details the network wide average speed (kph) for all vehicles for each of the scenarios in both the AM and PM peak periods.

Table 11: Network Wide Average Journey Speeds – AM Peak Period (07:00-10:00)

Scenario Average Journey Speed (kph)

1 2011 Base Year 36.8

2 2026 Existing Commitment Only 35.4

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 32.3

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 31.4

5 2026 Reference Case + Development on Land at Coate Bridge 29.5

6 2026 Reference Case + Development on Land north-east of Roundway Park 29.3


December 2011


Table 12: Network Wide Average Journey Speeds – PM Peak Period (16:00-19:00)

Network Wide Average Journey Time 7.6. To provide an indication as to the overall performance of the modelled highway

network for each of the scenarios tested, graphs output from S-Paramics representing ‘average journey times’ for all vehicles on the network have been produced for both the AM and PM peak periods, and are reproduced at Appendix E.

7.7. The network wide ‘average journey time’ is a good indicator as to the relative

performance of each of the scenarios in terms of queuing and delay on the modelled highway network throughout the time periods modelled. This output is commonly used to assess the overall performance of highway networks for S-Paramics models of this size.

7.8. Tables 13 & 14 summarise the network wide ‘average journey times’ for each of

the scenarios for both the AM peak hour (08:00-09:00) and PM peak hour (17:00-18:00) time periods. The tables also show the increase in average journey times for each of the 2026 model forecast scenarios.

7.9. The tables show that average journey times increase with increasing numbers of

trips on the network as a consequence of increased levels of congestion.

Scenario Average Journey Speed (kph)

1 2011 Base Year 34.7

2 2026 Existing Commitment Only 31.8

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 25.4

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 24.0

5 2026 Reference Case + Development on Land at Coate Bridge 20.1

6 2026 Reference Case + Development on Land north-east of Roundway Park 20.0


December 2011


Table 13: Network Wide Average Journey Times - AM Peak Hour (08:00-09:00)

Table 14: Network Wide Average Journey Times - PM Peak Hour (17:00-18:00)

Scenario

Network Wide

Average Journey Time

(min:sec)

Increase in Average Journey Time

Compared to 2011 Base Year

(min:sec) %

1 2011 Base Year 5:46 - -

2 2026 Existing Commitment Only 6:02 +0:16 +5%

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 7:07 +1:21 +23%

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 7:29 +1:43 +30%

5 2026 Reference Case + Development on Land at Coate Bridge 8:21 +2:35 +45%

6 2026 Reference Case + Development on Land north-east of Roundway Park 8:16 +2:30 +43%

Scenario

Network Wide

Average Journey Time

(min:sec)

Increase in Average Journey Time

Compared to 2011 Base Year

(min:sec) %

1 2011 Base Year 6:16 - -







December 2011


A361 ‘Through Traffic’ Average Journey Time 7.10. In addition to network wide average journey times the average journey times for

journeys made between the A361 west of Devizes (zone 83) and the A361 east of Devizes (zone 85) have been derived for each of the scenarios and are represented in graphs output at Appendix F. The graphs represent average journey times for both eastbound and westbound traffic for both the AM and PM peak periods.

7.11. Tables 15 & 16 summarises the average journey times for A361 ‘through traffic’

(both eastbound and westbound) for both the AM and PM peak hours.

Table 15: A361 ‘Through Traffic’ Average Journey Times – AM Peak Hour (08:00-09:00)

Table 16: A361 ‘Through Traffic’ Average Journey Times – PM Peak Hour (17:00-18:00)

Scenario

A361 Through Traffic Average Journey Time (min:sec)

Eastbound Westbound

1 2011 Base Year 15:46 11:26

2 2026 Existing Commitment Only 17:06 12:21

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 22:39 12:45

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 24:14 13:11

5 2026 Reference Case + Development on Land at Coate Bridge 26:19 13:46

6 2026 Reference Case + Development on Land north-east of Roundway Park 26:15 13:44

Scenario

A361 Through Traffic Average Journey Time (min:sec)

Eastbound Westbound

1 2011 Base Year 12:26 17:43

2 2026 Existing Commitment Only 12:33 20:37

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 13:18 26:39

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 14:05 28:41

5 2026 Reference Case + Development on Land at Coate Bridge 16:14 33:57

6 2026 Reference Case + Development on Land north-east of Roundway Park 17:15 36:13


December 2011


Bus Journey Times 7.12. Tables 17 & 18 show the average bus journey times for all scheduled bus

services in Devizes for both the AM and PM peak period. The tables also show the increase in average bus journey times for each of the 2026 model forecast scenarios.

Table 17: Average Bus Journey Times–AM Peak Period (07:00-10:00)

Table 18: Average Bus Journey Times–PM Peak Period (16:00-19:00)

7.13. The above tables show that average bus journey times increase with increasing numbers of trips on the network as a consequence of increased levels of congestion.

Scenario

Average Bus Journey Time

(min:sec)

Increase in Average Bus Journey Time Compared to 2011

Base Year

(min:sec) %

1 2011 Base Year 18:46 - -






Scenario

Average Bus Journey Time

(min:sec)

Increase in Average Bus Journey Time Compared to 2011

Base Year

(min:sec) %

1 2011 Base Year 20:17 - -







December 2011


Vehicle Emissions 7.14. To accurately estimate emissions from each of the scenarios modelled the AIRE

(Analysis of Instantaneous Road Emissions) software module has been used. 7.15. The AIRE software was developed to enable micro-simulation outputs to be

accurately and efficiently interpreted to produce emissions estimates for multiple model runs. AIRE contains more accurate data on current engine types, and its use combined with micro-simulation model outputs results in a more refined estimate of vehicle emissions particularly when modelling urban networks with stop-start conditions.

7.16. The outputs from AIRE are oxides of nitrogen (NOX), particulate matter (PM10)

and total carbon with estimates produced for each vehicle at each simulated timestep that can be aggregated by individual link, per trip or across entire networks.

7.17. The fleet compositions and engine type forecasts included in AIRE are based on

the National Atmospheric Emissions Inventory (NAEI) datasets. This assumes that the proportion of older engine types decreases, and the proportion of newer, "cleaner" engines increases as time progresses. This has a significant impact on the emissions of NOX and PM10 which are very sensitive to fleet changes with reduced emissions resulting from an improved vehicle fleet.

7.18. Outputs from AIRE for the 2026 forecast year have been produced for both an

improved vehicle fleet, based on the NAEI dataset, and the existing 2011 vehicle fleet assuming the status-quo. This provides a range of values for each pollutant the level of which will be dependent on the extent to which improvements to vehicle fleet compositions and engine types come about in the future.

Network Wide Vehicle Emissions

7.19. Tables 19 & 20 shows the vehicle emissions in respect of NOX, PM10 and total carbon from all vehicles over the entire modelled highway network for each scenario in both the AM and PM modelled peak periods.

Table 19: Network Wide Vehicle Emissions – AM Peak (07:00-10:00)

Scenario NOX (kg) PM10 (kg)

Carbon (kg)

1 2011 Base Year 38.6 1.169 4537

2 2026 Existing Commitment Only 29.1 – 42.5 0.748 – 1.273 4897 - 4900

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 30.7 – 44.2 0.789 – 1.316 5206 -5210

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 31.3 – 44.9 0.801 – 1.332 5323 - 5325

5 2026 Reference Case + Development on Land at Coate Bridge 32.0 – 46.6 0.815 – 1.366 5458 - 5465

6 2026 Reference Case + Development on Land north-east of Roundway Park 32.3 – 46.7 0.823 – 1.375 5474 - 5475


December 2011


Table 20: Network Wide Vehicle Emissions – PM Peak (16:00-19:00)

7.20. The results output from AIRE show that in 2026 both NOX and PM10 would be

lower than existing levels if the assumed vehicle fleet and engine types assumed by the NAEI materialise. The improved vehicle fleet in the future year offsets the increased volumes/congestion. This is not the case for the carbon emissions which are not as affected by the fleet changes (scope for decreases in carbon output with better engines is not as great as that for reducing NOx and PM10 emissions) and as such even though the fleet may be more efficient in the future year, this is not offset by the increased flows/congestion in the context of the carbon emitted.

7.21. If however no improvements to vehicles fleet and engine types were to come

about then there would be an increase in NOX, PM10 and total carbon emitted as a consequence of increased volumes and congestion on the highway network. Local Area Vehicle Emissions

7.22. Air quality monitoring in Devizes has highlighted a number of locations where air quality is a particular concern.

7.23. Figure 5 shows the three locations from which vehicle emissions have been

specifically collected, namely, Shane’s Castle, Brewery Corner and The Green/Roses Roundabouts. Each of these local areas experience significant traffic volumes and queuing at peak periods.


Carbon (kg)

1 2011 Base Year 36.5 1.173 4780

2 2026 Existing Commitment Only 28.8 – 40.3 0.798 – 1.277 5221 – 5222

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 31.1 – 44.0 0.847 – 1.368 5712 – 5719

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 32.1 – 45.4 0.870 – 1.403 5907 – 5915

5 2026 Reference Case + Development on Land at Coate Bridge 33.1 – 46.9 0.887 – 1.440 6134 – 6145

6 2026 Reference Case + Development on Land north-east of Roundway Park 33.0 – 46.3 0.884 – 1.412 6103 – 6116


December 2011


7.24. Tables 21 & 22 shows the vehicle emissions is respect of NOX, PM10 and total carbon from all vehicles on those links representing the Shane’s Castle local area in both the AM and PM peak periods. As with the network wide statistics, 2026 values are provided assuming both an improved vehicle fleet, based on the NAEI dataset, and the existing 2011 vehicle fleet.

Table 21: Shane’s Castle Local Area Vehicle Emissions – AM Peak (07:00-10:00)

Table 22: Shane’s Castle Local Area Vehicle Emissions – PM Peak (16:00-19:00)


Carbon (kg)

1 2011 Base Year 0.660 0.016 69.6

2 2026 Existing Commitment Only 0.495 – 0.729 0.010 – 0.018 74.9 – 74.9

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 0.496 – 0.720 0.010 – 0.018 76.1 – 76.2

4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 0.495 – 0.710 0.010 – 0.017 75.7 – 75.9

5 2026 Reference Case + Development on Land at Coate Bridge 0.503 – 0.733 0.010 – 0.018 76.4 – 76.6

6 2026 Reference Case + Development on Land north-east of Roundway Park 0.520 – 0.758 0.011 – 0.018 79.1 – 79.3


Carbon (kg)

1 2011 Base Year 0.497 0.013 57.6



4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 0.389 – 0.556 0.009 – 0.015 61.6 – 62.0




December 2011


7.25. Tables 23 & 24 shows the vehicle emissions is respect of NOX, PM10 and total carbon from all vehicles on those links representing the Brewery Corner local area in both the AM and PM peak periods. 2026 values are provided assuming both an improved vehicle fleet, based on the NAEI dataset, and the existing 2011 vehicle fleet.

Table 23: Brewery Corner Local Area Vehicle Emissions – AM Peak (07:00-10:00)

Table 24: Brewery Corner Local Area Vehicle Emissions – PM Peak (16:00-19:00)


Carbon (kg)

1 2011 Base Year 0.464 0.011 48.9



4 2026 Reference Case + Development on Land off the A342 south of Marshall Rd 0.351 – 0.499 0.007 – 0.012 52.7 - 52.8




Carbon (kg)

1 2011 Base Year 0.432 0.010 50.9

2 2026 Existing Commitment Only 0.336 – 0.460 0.007 – 0.011 53.6 - 53.7

3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 0.346 – 0.483 0.007 – 0.012 55.0 - 55.1


5 2026 Reference Case + Development on Land at Coate Bridge 0.349 – 0.490 0.007 – 0.012 55.6 - 55.6

6 2026 Reference Case + Development on Land north-east of Roundway Park 0.348 – 0.482 0.007 – 0.012 55.4 - 55.5


December 2011


7.26. Tables 25 & 26 shows the vehicle emissions is respect of NOX, PM10 and total carbon from all vehicles on those links representing The Green/Roses local area in both the AM and PM peak periods. 2026 values are provided assuming both an improved vehicle fleet, based on the NAEI dataset, and the existing 2011 vehicle fleet.

Table 25: The Green / Roses Local Area Vehicle Emissions – AM Peak (07:00-10:00)

Table 26: The Green / Roses Local Area Vehicle Emissions – PM Peak (16:00-19:00)


Carbon (kg)

1 2011 Base Year 1.099 0.028 127.1


3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 0.905 – 1.247 0.019 - 0.031 142.2 - 142.9



6 2026 Reference Case + Development on Land north-east of Roundway Park 0.929 – 1.288 0.020 - 0.032 146.2 - 147.0


Carbon (kg)

1 2011 Base Year 1.190 0.031 147.4


3 2026 Existing Commitments + Core Strategy Scenario (Reference Case) 0.984 – 1.333 0.022 – 0.034 163.6 - 164.5



6 2026 Reference Case + Development on Land north-east of Roundway Park 0.988 – 1.327 0.022 – 0.034 164.8 - 165.6

Fig

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s

Wiltshire CouncilStratton Park HouseWanborough RoadSwindonSN3 4HG

T 01793 828000F 01793 835500E [email protected] www.pfaplc.com

Client

Figure Title

Project

Figure No

Figure 1

Based on Ordnance Survey Map with the permission of the Controller of Her Majesty’s Stationery Office.Crown Copyright PFA ConsultingLicence No. AL100000054

0 1km

Devizes Traffic Model

Devizes Traffic Model Study Area

DateDrawn ByChecked ByScaleFile RefDoc Ref

November 2011ENJA1:50,000 @ A4W423/Figures/Fig1.aiW423

Figure 2Figure NoFigure No

Figure TitleFigure Title

ProjectProject

ClientClient

0 1km


Wiltshire Council

Developments Includedin 2026 Model Forecasting



November 2011ENJASee Scale BarW423/Figures/Fig2.aiW423


N

Stratton Park HouseWanborough Road

SwindonSN3 4HG

T 01793 828000F 01793 835500

E [email protected] www.pfaplc.com

Additional Larger ResidentialSites

Core Strategy PotentialDevelopment Sites

Committed Development

Note: Site boundariesare indicative only.

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Wiltshire Council

AM Peak Hour (08:00-9:00)Modelled Link Flows





N


SwindonSN3 4HG

T 01793 828000F 01793 835500


Scenarios:

2011 Base Year

2026 Existing Commitment Only

2026 Existing Commitments + Core Strategy Scenario (Reference Case)

2026 Reference Case + Development on the Land off the A342 south of Marshall Rd

2026 Reference Case + Development on Land at Coate Bridge

2026 Reference Case + Development on Land north-east of Roundway Park

Note: Traffic flows are two-way flows derived from S-Paramics traffic model.

A342

A361

A361

Horton Rd

A360

A342

771803797799807804

865900889942902900

462474500524524510

403339507489506538

884835998100610521031

201420712121213121062159

157816151656167216601669

120212281189119211811188 293

298292290292295

136814891387136413731403

170017451698163815261668

143715031506142913981446

786729716807830793

116611871282134814471340

13761355135814241438140510571082

1084109310811087

847871871876876871

114510691087111711281060

201420402011203720052009

683759763743713786

57819310412493

115211831185118511811185

387486490468457508

786824821824822821



ProjectProject

ClientClient

0 1km


Wiltshire Council

PM Peak Hour (17:00-18:00)Modelled Link Flows





N


SwindonSN3 4HG

T 01793 828000F 01793 835500


Scenarios:

2011 Base Year

2026 Existing Commitment Only

2026 Existing Commitments + Core Strategy Scenario (Reference Case)

2026 Reference Case + Development on the Land off the A342 south of Marshall Rd

2026 Reference Case + Development on Land at Coate Bridge

2026 Reference Case + Development on Land north-east of Roundway Park

Note: Traffic flows are two-way flows derived from S-Paramics traffic model.

A342

A361

A361

Horton Rd

A360

A342

235245234240239239

121012331177118811171085

138913691358137713221318

210821642158216920952093

833870851881968814

467503493511488470

786819805809802802

865872858928871880

123812651281132112771241

17311724178017551789174112041235

1221122012171204

914944934933930922

110510571134110911441110

129413091303127912911285

227264246236253219

158115981620159416171660

168817111716169217151770

110211851084107210081022

202120382030197019361925

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114111781158116311591161

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7798106131142118



ProjectProject

ClientClient

0 250m


Wiltshire Council

Local Areas Assessed for Air Quality





N


SwindonSN3 4HG

T 01793 828000F 01793 835500


Links from which NOX,PMIO and total carbonemissions have beencollected from the S-Paramics Traffic Model

1. Shane’s Castle

2. Brewery Corner

3. The Green/Roses Roundabouts

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TEMPRO TRAFFIC GROWTH

External to External 'Through Traffic'

2011 to 2026

Wiltshire

Origin 1.13251.1009 Average: 1.1167

Wiltshire

Origin 1.11701.1386 Average: 1.1278Destination

Weekday AM Peak Car Driver Trip End Growth for

Weekday PM Peak Car Driver Trip End Growth for

Wiltshire

TRAFFIC GROWTH:

TEMPRO Local AM Peak Hour Factors

Destination

TEMPRO Local PM Peak Hour Factors

Local Tempro Zone:

Traffic Growth factors to be applied to the traffic model using factors derived from TEMPRO (Dataset Version6.2) for highways only models.

November 2011F:\Workfile\W423\Tempro\TEMPRO Calculations_Traffic Model v1.1 Rev A.xlsx


Internal Traffic (trips with origin and/or destination in Devizes)

2011 to 2026

Devizes (46UB1)

Origin 1.04281.0531 Average: 1.0480

Devizes (46UB1)


Local Tempro Zone:


TRAFFIC GROWTH:


Destination



Devizes (46UB1)

Traffic Growth factors to be applied to the traffic model using factors derived from TEMPRO (Dataset Version6.2) for highways only models.



Internal Traffic (trips with origin and/or destination in Devizes)

Alternative planning assumptions applied representing only committed housing development in Devizes 2011-2026

2011 to 2026

Devizes (46UB1)

Origin 0.99591.0465 Average: 1.0212

Devizes (46UB1)


Local Tempro Zone:


TRAFFIC GROWTH:


Destination



Devizes (46UB1)

Traffic Growth factors to be applied to the traffic model using factors derived from TEMPRO (Dataset Version6.2) for highways only models, allowing for 'alternative planning assumptions'.


Region Year Data Motorway Trunk Principal MinorSouth West 2003 Sum of CARS 6.1 5.3 12.5 13.6 37.5

Sum of LGV 0.8 0.7 1.7 2.2 5.5Sum of Large Vehicles 1.0 0.5 0.8 0.6 2.9Sum of TOTAL Bvk 7.9 6.5 15.0 16.5 45.9Sum of CO2 MT 2.5 1.5 2.9 3.2 10.2Sum of Average Delay S/Vkm 0.6 4.3 6.2 6.7 5.1Sum of Vehicle Speed Km/Hr 109.3 77.7 65.7 46.2 61.9

2015 Sum of CARS 2% 5% 5% 6% 5%Sum of LGV 30% 31% 31% 31% 31%Sum of Rigid 23% 16% 12% 14% 16%Sum of Artic -10% -5% -3% -7% -8%Sum of PSV -5% -5% -5% -5% -5%Sum of TOTAL Bvk 5% 8% 8% 10% 8%Sum of CO2 MT -13% -11% -12% -10% -11%Sum of Average Delay S/Vkm 3% 2% 9% 4% 7%Sum of Vehicle Speed Km/Hr 0% 0% -1% 0% -1%

2025 Sum of CARS 26% 28% 22% 23% 24%Sum of LGV 63% 64% 63% 64% 63%Sum of Rigid 30% 23% 19% 21% 22%Sum of Artic -3% 4% 6% -1% 0%Sum of PSV -5% -5% -5% -5% -5%Sum of TOTAL Bvk 27% 31% 26% 28% 28%Sum of CO2 MT -21% -20% -24% -23% -22%Sum of Average Delay S/Vkm 38% 11% 29% 20% 23%Sum of Vehicle Speed Km/Hr 0% -1% -3% -2% -2%

2035 Sum of CARS 44% 46% 36% 38% 39%Sum of LGV 105% 104% 103% 105% 104%Sum of Rigid 36% 29% 24% 26% 28%Sum of Artic 7% 11% 12% 6% 9%Sum of PSV -5% -5% -5% -5% -5%Sum of TOTAL Bvk 47% 50% 42% 46% 46%Sum of CO2 MT -20% -20% -24% -24% -22%Sum of Average Delay S/Vkm 139% 38% 52% 34% 43%Sum of Vehicle Speed Km/Hr -2% -3% -5% -3% -3%

HGV Growth 2011-2026 for South West Principle Road Type:

HGV (Rigid) Growth 2011-2026 = 11.5%HGV (Artic) Growth 2011-2026 = 8.6% HGV Growth (assumed proportions 72% Rigid, 28% Artic) 2011-2026 10.7%

Regional Traffic Forecasts - National Transport Model (NTM) - March 2010

Road TypeAll Roads


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2026 Model Forecasting - Development Schedule

Generations Attractions Generations Attractions Generations Attractions Generations AttractionsCommitted Development

Residential:

Former Spitalcroft Allotments 1 8 units 70 70 Local Trip Rate 0.756 0.175 6 1 0.513 0.813 4 7

Land at Quakers Walk 2 87 units 49 49 Local Trip Rate 0.756 0.175 66 15 0.513 0.813 45 71

Land at Naughton Avenue 3 7 units 58 58 Local Trip Rate 0.756 0.175 5 1 0.513 0.813 4 6

Land at Bureau West 4 118 units 62 58 Local Trip Rate 0.756 0.175 89 21 0.513 0.813 60 96

Employment:

Land at Nurstead Road (Saved Kennet District Plan allocation) 5 1.5 Ha 89 39 TRICS 20.51 34.56 31 52 28.23 13.25 42 20

Other:

Relocated St Peter' s School at Quakers Walk 6 300 pupils 72 15 TRICS 0.295 0.364 89 109 0.090 0.036 27 11

B&Q Store, Hambleton Avenue 7 2275 gfa 59 59 TRICS 1.973 2.921 45 66 6.178 5.912 141 134

Core Strategy Scenario - Potential Sites

Residential:

Former Clinic, Green Lane 8 50 units 73 29 Local Trip Rate 0.756 0.175 38 9 0.513 0.813 26 41

Garden Trading Estate 9 70 units 74 55 Local Trip Rate 0.756 0.175 53 12 0.513 0.813 36 57

Land South of Parkfield 10 60 units 75 49 Local Trip Rate 0.756 0.175 45 11 0.513 0.813 31 49

Football Club off Nursteed Road 11 100 units 76 35 Local Trip Rate 0.756 0.175 76 18 0.513 0.813 51 81

Land off Hambleton Avenue 12 30 units 77 58 Local Trip Rate 0.756 0.175 23 5 0.513 0.813 15 24

Land adjoining Lay Wood 13 100 units 78 58 Local Trip Rate 0.756 0.175 76 18 0.513 0.813 51 81

Devizes Wharf 14 30 units 79 48 Local Trip Rate 0.756 0.175 23 5 0.513 0.813 15 24

St Peters School Site 15 25 units 15 16 Local Trip Rate 0.756 0.175 19 4 0.513 0.813 13 20

Other Small Sites (Windfall) 170 units Internal Zones n/a Local Trip Rate 0.756 0.175 129 30 0.513 0.813 87 138

Employment:

Land between A361 and Horton Road 16 8.4 Ha 90 63 TRICS 20.51 34.56 172 290 28.23 13.25 237 111

Additional Larger Peripheral Residential Sites

Land off the A342 south of Marshall Road 17 220 units 91 29,37,40,49,52,55,58 Local Trip Rate 0.756 0.175 166 39 0.513 0.813 113 179

Land at Coate Bridge 18 400 units 92 29,37,40,49,52,55,58 Local Trip Rate 0.756 0.175 302 70 0.513 0.813 205 325

Land to the North East of Roundway Park 19 400 units 93 29,37,40,49,52,55,58 Local Trip Rate 0.756 0.175 302 70 0.513 0.813 205 325

Development 2011-2026 Existing Zones used for Distribution

Development Zone

Ref No. Type AM Trip Rate AM Trips (07:00-10:00) PM Trip Rate PM Trips (16:00-19:00)Trip Rate Source

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2026 Reference Case + Development on Land at Coate Bridge 2026 Reference Case + Development on Land north-east of Roundway Park

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A361 Westbound 'Through Traffic' Average Journey Times - PM Peak




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