appendix d modelling report - slough.gov.uk · appendix d modelling report . ... atkins saturn...

Appendix D

Modelling Report

Burnham Station and Access Improvements SATURN modelling summary Slough Borough Council

28 October 2015

Burnham Station and Access Improvements SATURN modelling summary

Atkins SATURN modelling summary | 2.0 | 28 October 2015 | 5143213

Notice This document and its contents have been prepared and are intended solely for Slough Borough Council’s information and use in relation to Burnham Station and Access Improvements Scheme

Atkins Limited assumes no responsibility to any other party in respect of or arising out of or in connection with this document and/or its contents.

This document has 29 pages including the cover.

Document history

Job number: 5143213 Document ref: 5143213-DOC-002

Revision Purpose description Originated Checked Reviewed Authorised Date

Rev 0.1 Draft NAU

Rev 0.2 Draft NAU AL

Rev 0.3 Draft NAU AL

Rev 1.0 Draft for issue NAU AL DW

Rev 2.0 Issue NAU AL EN DW 28/10/15

Client signoff

Client Slough Borough Council

Project Burnham Station and Access Improvements

Document title SATURN modelling summary

Job no. 5143213

Copy no.

Document reference

5143213-DOC-002


Atkins SATURN modelling summary | 2.0 | 28 October 2015 | 5143213

Table of contents

Chapter Pages 1. Introduction 4 1.1. Transport models 4

2. Modelling approach 5 2.1. Do Minimum model construction 5 2.2. Do minimum model validation 8 2.3. Do Something model construction 10

3. Modelling results 11 3.1. Do Minimum V/C analysis 11 3.2. Do Something results 13

4. Economic Impacts 19

5. Assumptions 22

Appendix A. Journey Time Surveys 23 A.1. Location of Journey Time Surveys 23 A.2. Journey Time Comparisons 26

Tables Table 2-1 Burnham Station Area Improvements Modelling Zone 17009 Re-Allocation ............................ 6 Table 2-2 Burnham Station Area Improvements Modelling Zone 18012 Re-Allocation ............................ 6 Table 2-3 Journey Time Survey Routes .................................................................................................... 8 Table 2-4 Comparison of modelled and observed journey times during the AM Peak ............................. 8 Table 2-5 Comparison of modelled and observed journey times during the PM Peak ............................. 9 Table 3-1 Flow Comparison 2017 AM ..................................................................................................... 14 Table 3-2 Flow Comparison 2017 PM ..................................................................................................... 14 Table 3-3 Flow Comparison 2027 AM ..................................................................................................... 15 Table 3-4 Flow Comparison 2027 PM ..................................................................................................... 15 Table 3-5 Flow Comparison 2017 AM ..................................................................................................... 17 Table 3-6 Flow Comparison 2017 PM ..................................................................................................... 17 Table 3-7 Flow Comparison 2027 AM ..................................................................................................... 18 Table 3-8 Flow Comparison 2027 PM ..................................................................................................... 18 Table 4-1 TEE Table for DS1 – Core Scenario ....................................................................................... 20 Table 4-2 TEE Table for DS2 – Alternative Scenario .............................................................................. 21

Figures Figure 1-1 2009 SMMTS model core study area ........................................................................................ 5 Figure 2-1 Zoning system before splitting zones ........................................................................................ 7 Figure 2-2 Zoning system after splitting zones ........................................................................................... 7 Figure 2-3 Burnham Lane Flow Differences ............................................................................................... 9 Figure 2-4 Station Road Flow Differences ................................................................................................ 10 Figure 3-1 Do Minimum 2017 AM Peak Link and Node V/C..................................................................... 11 Figure 3-2 Do Minimum 2017 PM Peak Link and Node V/C..................................................................... 12 Figure 3-3 Do Minimum 2027 AM Peak Link V/C ..................................................................................... 12 Figure 3-4 Do Minimum 2027 PM Peak Link V/C ..................................................................................... 13


Atkins SATURN modelling summary | 2.0 | 28 October 2015 | 5143213 5

1. Introduction This report summarises the SATURN modelling exercise undertaken by Atkins, which tests a number of highway network management scenarios around Burnham Station in the west of Slough. It is intended to provide a high level evidence base to Slough Borough Council, to determine the suitability of these potential highway changes and their impact on the wider network.

The tests are centred on investigating the implications of applying changes to the highway network around Station Road and Burnham Lane.

This technical note summarises the modelling approach taken to assess the proposals using SATURN and the subsequent use of TUBA to assess the economic benefits of the scheme.

1.1. Transport models The SATURN model was developed for use within the Slough Multi-Modal Transport Study (SMMTS) with the following components:

2009 Base Model – adapted and validated by Atkins from the 2004 model built by SDG (documented within the LMVR (January 2011);

2017 Do-Something – used for the assessment and appraisal of the Burnham Station and Access Improvements scheme.

The models cover the entire town of Slough, with a hinterland of Berkshire, Buckinghamshire and the London Boroughs of Ealing, Hillingdon and Hounslow, whilst the rest of the UK made up the external areas. The core study area is shown Figure 1-1.



Figure 1-1 2009 SMMTS model core study area

2. Modelling approach The SATURN model used has two time periods, AM peak (08:00-09:00) and PM peak (17:00-18:00). There are also one hour pre-peak periods for both AM and PM peak operated by PASSQ function within SATURN. There are five modelled user classes, including, car employer business, car commuting, car other, LGV and HGV. Model scenarios are set out below.

2017 Do Minimum 2017 DS1 scenario from A355 Route Enhancement scheme with zoning system changed around Burnham Station;

2017 Do Something 1 (Core Scenario) – constructed from 2017 Do Minimum scenario with changes to Station Road and Burnham Lane to represent full closure of Station Road;

2017 Do Something 2 (Alternative Scenario) – constructed from 2017 Do Minimum scenario with changes to Station Road and Burnham Lane to represent part closure of Station Road;

2027 Do Minimum 2027 DS1 scenario from A355 Route Enhancement scheme with zoning system changed around Burnham Station;

2027 Do Something 1 (Core Scenario) – constructed from 2027 Do Minimum scenario with changes to Station Road and Burnham Lane to represent full closure of Station Road;

2027 Do Something 2 (Alternative Scenario) – constructed from 2027 Do Minimum scenario with changes to Station Road and Burnham Lane to represent part closure of Station Road.

2.1. Do Minimum model construction Minor changes have been made to the link and node structure in order to represent a reference case for 2017 from the A355 Route Enhancement DS1 scenario. The most important change has been changing the zoning structure around Burnham Station to better represent existing conditions. Further details on the methodology used to split the zones can be found in the section below.



Zone Splitting The zone structure of the model was amended around the Burnham Station area, to capture more realistic entry points onto the network close to the scheme.

The model has one combined zone for Stanhope Road and Whittle Parkway which then feeds onto the network at Bath Road and also Station Road. In reality, Whittle Parkway only feeds onto the network via Bath Road and any northbound traffic within the model originating from Whittle Parkway could therefore bypass the Station Road/Bath Road signalised junction.

The model also has one combined zone for Iona Crescent, Brook Crescent and the Bath Road Retail Park. The loading points for this zone are Station Road, Burnham Lane and Bath Road, indicating that any Retail Park trips could be loaded on to the network via Station Road and Burnham Lane, which is not the case in reality.

Therefore the model network within the study area has been recoded to provide a more realistic representation of the operation of the existing road network. The re-coding has been informed by previous work undertaken in this area of the model. The percentage split of the demand from the existing zones into the new zones along with the loading locations of the new zones is summarised in the tables below.

Table 2-1 Burnham Station Area Improvements Modelling Zone 17009 Re-Allocation

2009 Slough Traffic Model Burnham Station Area Improvements Modelling Base

Zone Network Loading Zone Zone Description Network Loading Split

17009 A4 & Station Road 17009 Whittle Parkway A4 67%

30006 Stanhope Road Station Road 33%

Total 100% The zone 17009 has been split with 67% remaining as zone 17009 and 33% forming new zone 30006. Zone 17009 only loads onto Bath Road and zone 30006 only loads on to Station Road. This split is considered reasonable based on Census population statistics.

Zone 17009, representing the retail and business units, will load onto both Whittle Parkway and Kelpatrick Road provide access to the A4 as on the ground. Zone 30006 will load onto a road that represents Stanhope Road, Balmoral Close and Suffolk Close and provides access to Station Road as on the ground.

Table 2-2 Burnham Station Area Improvements Modelling Zone 18012 Re-Allocation

2009 Slough Traffic Model Burnham Station Area Improvements Modelling Base

Zone Network Loading Zone Zone Description Network Loading Split

18012 A4, Station Road &

Burnham Lane

18012 Bath Road Retail Park A4 90%

30007 Iona Crescent Station Road 5%

30008 Brooke Crescent Burnham Lane 5%

Total 100% The zone 18012 has been split into 3 zones, 90% remaining as zone 18012, 5% forming the new zone 30007, and 5% forming the new zone 30008. The demand split was also considered reasonable given the small number of houses on both Iona Crescent and Brook Crescent relative to the demand generated by the retail park.

Images showing the zoning system before and after the split are shown in Figure 2-1 and Figure 2-2 below.



Figure 2-1 Zoning system before splitting zones

Figure 2-2 Zoning system after splitting zones



2.2. Do minimum model validation Due to the nature of the scheme and the scope of the funding being requested from the LEP, the modelling for the Burnham Station and Access Improvements scheme does not have to be fully compliant with WebTAG standards for calibration and validation. However, journey times (on several routes) and traffic counts (on Burnham Lane and Station Road) observed in October 2015 have been used for the basis of a comparison exercise against the Do Minimum model. This exercise shows a reasonably close fit and we consider the model fit for purpose in use of the model to test the impacts of the scheme.

Journey time analysis Atkins was provided with journey time data collected in October 2015. Four different routes were surveyed, grouped into four different colours. These are summarised in Table 2-3 and maps showing the routes can be found in Appendix A.

Table 2-3 Journey Time Survey Routes

Route From To Comments

Green Bath Road / M4 Junction 7 Burnham Station via Dover Road Reverse journey too

Blue Dover Road / Buckingham Avenue

Dover Road / Buckingham Avenue via Slough Trading Estate

Loop clockwise and anti-clockwise

Orange Bath Road / M4 Junction 7 Bath Road / M4 Junction 7 via Five Points Junction and Station Road

Loop clockwise and anti-clockwise

Pink Five Points Junction Slough Trading Estate via Buckingham Avenue

Reverse journey via Burnham Lane

AM Comparison Journey time information on green, blue, orange and pink routes were collected over two October mornings (between 8:00 - 10:00am). A comparison of observed and modelled journey times are shown in Table 2-4 below.

Table 2-4 Comparison of modelled and observed journey times during the AM Peak

Route Do Minimum Modelled (seconds)

Observed (seconds) DM – Observed

(seconds)

Green 1134 1116 18 (2%)

Blue Clockwise 263 377 -114 (-43%)

Blue Anticlockwise - - -

Orange Clockwise 776 745 31 (4%)

Orange Anticlockwise 768 935 -167 (-22%)

Pink 1029 911 118 (11%)

From table above, it can be seen that modelled and observed journey times match closely, with the exception of the blue route. It is worth noting though, that the blue route travels through the trading estate, and a feature like this is very difficult to model due to its nature.

On the orange route significant disruption was reported on the 15th October (Journey time was doubled) and hence only data from the 13th October was used for comparison purposes.

As expected, modelled journey times were higher than observed journey times as the base year of the model was 2017.

PM Comparison Journey time information on green, orange and pink routes was collected on the 13th and 15th October afternoon (16:45 – 18:00). Comparison of observed and modelled journey times are shown below.



Table 2-5 Comparison of modelled and observed journey times during the PM Peak

Route Do Minimum Modelled (seconds)

Observed (seconds) Difference (seconds)

Green 1074 1121 -47 (-4%)

Orange Clockwise 806 1034 -228 (-28%)

Orange Anticlockwise 848 1174 -326 (-38%)

Pink 1273 1582 -309 (-24%)

In contrast with the AM, in the PM peak the difference between observed and modelled journey times is more significant. The green route is the only one that shows a good fit between modelled and observed journey times. The model seems to consistently underestimate journey times compared to observed journey times.

Outcome Journey time data for four different routes was provided by Slough Borough Council. Overall, there seemed to be quite a stark contrast with AM and PM journey times when comparing observed and modelled times.

The model better represented conditions observed in the AM peak than the PM peak. Nevertheless, it should be noted that only data for two days was collected (In some routes data was only collected in one day). Moreover, the two days were in the same week, which may have been affected by unreasonably good / bad network performance. In order to get a better understanding of the robustness of the model, journey times should have been collected for an extended period of time, and if resources had been available, the model should have been recalibrated using traffic counts in the area.

Traffic volume analysis Slough Borough Council provided access to their Automatic Traffic Counter (ATC) database for the purpose of this project. The database included traffic count data at various locations around Slough, including two sites near Burnham Station. These are shown below.

Figure 2-3 Burnham Lane Flow Differences



Figure 2-4 Station Road Flow Differences

Figure 2-3 and Figure 2-4 show the comparison of modelled flows and observed flows in Station Road and Burnham lane.

The model tends to overestimate the flows in both time periods. This is expected as the base year of the model is 2017.

2.3. Do Something model construction Two scenarios with two time periods were modelled, 2017 and 2027. Changes to the network included:

DS1 (Core Scenario)

Station Road Bridge closed to traffic in both directions; Traffic lights at Station Road / Station Access removed and replaced by priority junction and gyratory; Burnham Lane changed to southbound traffic flow only; and Signal timings in the vicinity of Burnham Station optimised to match the new flow patterns.

DS2 (Alternative Scenario)

Station Road traffic restricted to northbound only; Traffic lights at Station Road / Station Access removed and replaced by priority junction and gyratory

Burnham Lane changed to southbound traffic flow only; and Signal timings in the vicinity of Burnham Station optimised to match the new flow patterns.

Similar to the Do Minimum scenario the zoning system was amended to better represent existing conditions in the area.

It should also be noted that SATURN is beneficial in providing a strategic overview of a highway network based on approximations of the junctions to replicate average delay for the purpose of understanding the route choices that highway users make, and how they are influenced by a range of transport interventions. However, it is not designed to provide detailed junction assessment or replicate queueing patterns developing and dissipating over the course of a given time period.



3. Modelling results

3.1. Do Minimum V/C analysis To inform the assessment, reference is made to the Volume to Capacity ratios (V/C ratios) of the links and nodes (junctions) to identify where the congestion hotspots occur within the network.

The link V/C ratio allows the identification of specific junction arms which are likely to become congested over the course of the peak hour. The junction V/C ratio represents the average V/C across all approaches to a given junction. A minimum value of 85% V/C is used to highlight the areas of the network which SATURN shows are congested in the AM and PM networks. This assessment allows us to display graphically where the congestion issues in the Do Minimum scenario lie. SATURN plots for the detailed study area, showing the 2017/27 AM and PM peak V/C outputs, are shown in the figures below.

Figure 3-1 Do Minimum 2017 AM Peak Link and Node V/C



Figure 3-2 Do Minimum 2017 PM Peak Link and Node V/C

Figure 3-3 Do Minimum 2027 AM Peak Link V/C



Figure 3-4 Do Minimum 2027 PM Peak Link V/C

Both modelled years display similar levels of congestion. Areas where the capacity is an issue include A4 / Bath Road M4 Junction in both AM and PM peaks and Station Road, which experiences a more acute capacity problem in the PM peak.

Key junctions that present a congestion problem include M4 J7 and A4 Bath Road / Lent Rise.

3.2. Do Something results

3.2.1. DS1 (Core Scenario) – Full Closure – Results The tables below show differences in traffic flows between Do Something 1 (Core Scenario) and Do Minimum. As one would expect this induced a lot of rerouting, causing additional traffic in neighbouring bridges. Of these, Dover Road experience the highest change in flows, particularly in the northbound direction. A very significant reduction is observed at Station Road as expected.



Table 3-1 Flow Comparison 2017 AM

Road Do Minimum (Vehicles) Do Something 1 (Vehicles) DS1 – DM (%)

Car LGV HGV Total Car LGV HGV Total Car LGV HGV Total

Station Road NB 385 4 0 389 0 0 0 0 -100% -100% -100% -100%

Station Road SB 479 20 0 499 0 0 0 0 -100% -100% -100% -100%

Dover Road NB 347 57 2 406 611 46 2 659 76% -19% -1% 62%

Dover Road SB 851 81 7 940 843 51 8 902 -1% -36% 0% -4%

Leigh Road NB 244 10 2 255 284 36 2 322 17% 262% 0% 26%

Leigh Road SB 936 103 8 1047 947 140 7 1094 1% 36% -14% 5%

Huntercombe Road NB 237 4 0 240 200 3 0 203 -16% -10% -4% -15%

Huntercombe Road SB 259 38 9 306 277 39 6 321 7% 1% -35% 5%

Burnham Road NB 297 23 0 320 0 0 0 0 -100% -100% -100% -100%

Burnham Road SB 0 0 0 0 267 1 0 268 100% 100% 100% 100%

Bath Road EB 995 85 16 1095 956 87 16 1059 -4% 3% 1% -3%

Bath Road WB 638 77 15 730 879 85 14 978 38% 10% -6% 34%

Table 3-2 Flow Comparison 2017 PM



Station Road NB 442 9 0 451 0 0 0 0 -100% -100% -100% -100%

Station Road SB 475 7 0 482 0 0 0 0 -100% -100% 100% -100%

Dover Road NB 825 122 0 947 1075 82 0 1157 30% -32% 51% 22%

Dover Road SB 405 17 4 427 437 12 4 453 8% -30% 0% 6%

Leigh Road NB 492 9 9 509 500 5 9 514 2% -45% 0% 1%

Leigh Road SB 511 51 5 567 626 46 5 678 23% -9% 0% 20%

Huntercombe Road NB 145 5 0 151 154 5 0 160 6% -7% -10% 6%

Huntercombe Road SB 314 40 8 362 325 19 4 348 3% -52% -51% -4%

Burnham Road NB 264 1 0 265 0 0 0 0 -100% -100% -100% -100%

Burnham Road SB 0 0 0 0 123 3 0 126 100% 100% 100% 100%

Bath Road EB 650 99 8 757 644 102 8 754 -1% 3% 0% 0%

Bath Road WB 903 31 5 939 1179 38 5 1221 31% 23% 0% 30%




Road Do Minimum (Vehicles) Do Something 1(Vehicles) DS1 – DM (%)


Station Road NB 411 15 0 426 0 0 0 0 -100% -100% -100% -100%

Station Road SB 469 14 0 483 0 0 0 0 -100% -100% -100% -100%

Dover Road NB 400 84 6 490 713 62 6 780 78% -27% 0% 59%

Dover Road SB 689 156 9 854 637 135 23 795 -7% -14% 162% -7%

Leigh Road NB 159 6 2 168 251 41 2 295 58% 554% 0% 76%

Leigh Road SB 1044 101 8 1153 1051 135 8 1194 1% 33% -1% 4%


Huntercombe Road SB 261 62 11 334 300 47 8 355 15% -24% -28% 6%

Burnham Road NB 368 30 0 398 0 0 0 0 -100% -100% -100% -100%

Burnham Road SB 0 0 0 0 257 0 0 258 100% 100% 100% 100%

Bath Road EB 850 111 17 978 900 120 3 1023 6% 8% -82% 5%

Bath Road WB 510 100 10 620 768 108 9 886 51% 8% -7% 43%




Station Road NB 475 8 0 483 0 0 0 0 -100% -100% 100% -100%

Station Road SB 448 7 0 455 0 0 0 0 -100% -100% 100% -100%

Dover Road NB 645 86 0 732 1115 80 0 1195 73% -7% 92% 63%

Dover Road SB 454 29 5 487 552 23 5 580 22% -19% 0% 19%

Leigh Road NB 428 11 9 448 486 10 9 505 14% -5% -1% 13%

Leigh Road SB 515 71 6 592 639 70 6 715 24% -1% 0% 21%



Burnham Road NB 374 3 1 378 0 0 0 0 -100% -100% -100% -100%

Burnham Road SB 0 0 0 0 115 8 0 122 100% 100% 100% 100%

Bath Road EB 487 136 9 631 619 136 8 763 27% 0% -9% 21%

Bath Road WB 584 121 5 710 898 122 5 1025 54% 1% 0% 44%



3.2.2. DS2 (Alternative Scenario) – Part Closure – Results Flow differences between Do Something 2 (Alternative Scenario) and Do Minimum are shown in the tables below for 2017 and 2027 modelled years in the AM and PM peaks.

Both time periods show a similar behaviour in the rerouting. Additional traffic is observed on Bath Road westbound with reduced traffic on the eastbound movement. This can be explained by the change in direction of Burnham Lane, which provides one way southbound movement and hence traffic coming from the east which would have crossed the railway line at Burnham Lane needs to continue to Station Road or beyond, depending on their final destination. Another road that experiences increased traffic Dover Road, once again most probably due to Burnham Lane being closed northbound, rerouting to additional railway crossing points. Station Road is open to northbound movement and does not experience a great change in overall flow change.






Station Road NB 385 4 0 389 419 3 0 423 9% -22% 1% 9%

Station Road SB 479 20 0 499 0 0 0 0 -100% -100% -100% -100%

Dover Road NB 347 57 2 406 459 56 2 517 32% -1% 2% 27%

Dover Road SB 851 81 7 940 871 57 8 935 2% -30% 1% -1%

Leigh Road NB 244 10 2 255 250 28 2 280 3% 181% 0% 10%

Leigh Road SB 936 103 8 1047 991 137 7 1134 6% 33% -15% 8%

Huntercombe Road NB 237 4 0 240 237 4 0 241 0% 3% -4% 0%

Huntercombe Road SB 259 38 9 306 251 39 6 295 -3% 1% -37% -4%

Burnham Road NB 297 23 0 320 0 0 0 0 -100% -100% -100% -100%

Burnham Road SB 0 0 0 0 213 4 0 217 100% 100% 100% 100%

Bath Road EB 995 85 16 1095 880 85 16 981 -12% 1% 0% -10%

Bath Road WB 638 77 15 730 919 85 17 1021 44% 10% 15% 40%




Station Road NB 442 9 0 451 386 8 0 394 -13% -11% -90% -13%

Station Road SB 475 7 0 482 0 0 0 0 -100% -100% 100% -100%

Dover Road NB 825 122 0 947 950 116 0 1067 15% -5% 100% 13%

Dover Road SB 405 17 4 427 475 15 4 494 17% -12% 0% 16%

Leigh Road NB 492 9 9 509 482 8 9 499 -2% -10% 0% -2%

Leigh Road SB 511 51 5 567 596 53 5 654 17% 3% 0% 15%


Huntercombe Road SB 314 40 8 362 323 20 4 347 3% -50% -49% -4%

Burnham Road NB 264 1 0 265 0 0 0 0 -100% -100% -100% -100%

Burnham Road SB 0 0 0 0 98 1 0 99 100% 100% 100% 100%

Bath Road EB 650 99 8 757 519 94 8 621 -20% -5% 0% -18%

Bath Road WB 903 31 5 939 1202 36 5 1243 33% 15% 0% 32%






Station Road NB 411 15 0 426 466 9 0 475 13% -42% 222% 11%

Station Road SB 469 14 0 483 0 0 0 0 -100% -100% -100% -100%

Dover Road NB 400 84 6 490 463 85 6 554 16% 2% 1% 13%

Dover Road SB 689 156 9 854 706 145 12 863 2% -7% 35% 1%

Leigh Road NB 159 6 2 168 205 25 2 233 29% 298% 0% 39%

Leigh Road SB 1044 101 8 1153 1070 129 8 1207 3% 28% -1% 5%

Huntercombe Road NB 180 4 1 185 182 4 1 187 1% -8% 36% 1%


Burnham Road NB 368 30 0 398 0 0 0 0 -100% -100% -100% -100%

Burnham Road SB 0 0 0 0 212 0 0 212 100% 100% 100% 100%

Bath Road EB 850 111 17 978 752 116 14 882 -12% 5% -17% -10%

Bath Road WB 510 100 10 620 826 108 10 944 62% 8% -6% 52%




Station Road NB 475 8 0 483 492 9 0 501 3% 19% 100% 4%

Station Road SB 448 7 0 455 0 0 0 0 -100% -100% 100% -100%

Dover Road NB 645 86 0 732 827 98 0 925 28% 13% 184% 26%

Dover Road SB 454 29 5 487 563 31 5 598 24% 8% 0% 23%

Leigh Road NB 428 11 9 448 461 12 9 483 8% 18% 0% 8%

Leigh Road SB 515 71 6 592 627 76 6 709 22% 7% 4% 20%

Huntercombe Road NB 150 6 0 156 150 6 0 156 0% 2% -13% 0%


Burnham Road NB 374 3 1 378 0 0 0 0 -100% -100% -100% -100%

Burnham Road SB 0 0 0 0 90 1 0 91 100% 100% 100% 100%

Bath Road EB 487 136 9 631 373 126 8 507 -23% -7% -9% -20%

Bath Road WB 584 121 5 710 908 122 5 1035 55% 1% 0% 46%



4. Economic Impacts The economic appraisal of the scheme used the DfT TUBA software (version 1.9.4) in order to capture the principal journey time and vehicle operating cost benefits generated by the scheme across the highway network. The primary inputs to the TUBA process were:

Trip, journey time and journey distance matrices from the SATURN models for 2017 and 2027 for both Do Minimum and Do Something scenarios;

Scheme costs and construction programme (cost profile); and Standard TUBA economic parameters for the growth in values of time and fuel costs over the appraisal

period.

The appraisal considered the 15-year period, following the assumed opening of the scheme during 2017. In line with current economic appraisal guidance for transport schemes, the following adjustments to scheme costs have also been made:

15% optimism bias has been added to the majority of risk-adjusted scheme costs; and Costs have been factored to 2010 prices and then discounted to 2010 in order to calculate the Present

Value of Costs (PVC). The PVC may therefore different to the quoted scheme cost.

The output from the economic appraisal is summarised in Transport Economic Efficiency (TEE) table contained below.



Table 4-1 TEE Table for DS1 – Core Scenario

Consumer - Commuting user benefits All Modes Road Rail

Travel Time -1,724 -1,724 - Vehicle operating costs -364 -364 - User charges 0 0 - During Construction & Maintenance 0 0 - NET CONSUMER - COMMUTING BENEFITS -2,088 (1a) -2,088 -

Consumer - Other user benefits All Modes Road Rail

Travel Time -1,412 -1,412 - Vehicle operating costs -223 -223 - User charges - - - During Construction & Maintenance - - - NET CONSUMER - OTHER BENEFITS -1,635 (1b) -1,635 -

Business All Modes Road Personal Road Freight Rail Personal Rail Freight

Travel Time -1,275 -843 -433 - - Vehicle operating costs -181 -38 -143 - - User charges - - - - - During Construction & Maintenance - - - - - Subtotal -1,456 (2) -881 -575 - -

Private Sector Provider Impacts All Modes Road Rail

Revenue 7,148 - 7,148 Operating costs - - - Investment costs - - - Grant/subsidy - - - Subtotal 7,148 (3) - 7,148

Other business Impacts Developer contributions - (4) - -

NET BUSINESS IMPACT 5,692

(5) = (2) + (3) + (4)

TOTAL

Present Value of Transport Economic Efficiency Benefits (TEE)

2,556 (6) = (1a)+ (1b) + (5)



Table 4-2 TEE Table for DS2 – Alternative Scenario

Consumer - Commuting user benefits All Modes Road Rail

Travel Time -325 -325 - Vehicle operating costs -215 -215 - User charges 0 0 - During Construction & Maintenance 0 0 - NET CONSUMER - COMMUTING BENEFITS -539 (1a) -539 -

Consumer - Other user benefits All Modes Road Rail

Travel Time -201 -201 - Vehicle operating costs -119 -119 - User charges - - - During Construction & Maintenance - - - NET CONSUMER - OTHER BENEFITS -319 (1b) -319 -

Business All Modes Road Personal Road Freight Rail Personal Rail Freight

Travel Time -283 -253 -30 - - Vehicle operating costs -109 -42 -68 - - User charges - - - - - During Construction & Maintenance - - - - - Subtotal -392 (2) -294 -98 - -

Private Sector Provider Impacts All Modes Road Rail

Revenue 7,148 - 7,148 Operating costs - - - Investment costs - - - Grant/subsidy - - - Subtotal 7,148 (3) - 7,148

Other business Impacts Developer contributions - (4) - -

NET BUSINESS IMPACT -6,756

(5) = (2) + (3) + (4)

TOTAL

Present Value of Transport Economic Efficiency Benefits (TEE)

5,898 (6) = (1a)+ (1b) + (5)



5. Assumptions The following key appraisal assumptions have been made:

The appraisal period is 2017 to 2031; A discount rate of 3.5% has been applied for 30 years from 2014; Two forecast years of 2017 and 2027 have been used; The uplift applied to account for optimism bias 15%, in line with WebTAG advice for highway schemes;

and Annual benefits have been factored up from the modelled daily peak periods. These benefits have been

assumed to apply over 253 working days per year



Appendix A. Journey Time Surveys

A.1. Location of Journey Time Surveys



A.2. Journey Time Comparisons

A.2.1. AM



A.2.2. PM

© Atkins Ltd except where stated otherwise. The Atkins logo, ‘Carbon Critical Design’ and the strapline ‘Plan Design Enable’ are trademarks of Atkins Ltd.

Atkins Transportation Euston Tower 286 Euston Road London NW1 3AT

appendix d modelling report - slough.gov.uk · appendix d modelling report . ... atkins saturn...

Documents