ECONOMIC ASSESSMENT REPORT - Somerset

REPORT NO 287584DF-PTT/04

M5 JUNCTION 25 MAJORSCHEME BUSINESS CASEECONOMIC ASSESSMENT REPORT

FINAL JULY 2016

Final

Project no: 287584DF-PTT/04Date: July 2016

–WSP | Parsons BrinckerhoffThe ForumBarnfield RoadExeterEX1 1QR

Tel: 01392 229 770http://www.wsp-pb.co.uk/

M5 JUNCTION 25 MAJORSCHEME BUSINESS CASEECONOMIC ASSESSMENT REPORTSomerset County Council

Q U A L I T Y M A N A G E M E N TISSUE/REVISION FIRST ISSUE REVISION 1 REVISION 2 REVISION 3

Remarks Draft Final

Date 20/05/16 07/07/16

Prepared by Holly Moon /Neal Dyson

Neal Dyson

Signature

Checked by Richard Sweet Richard Sweet

Signature

Authorised by Marcus Chick Marcus Chick

Signature

Project number 287584DF-PTT 287584DF-PTT

Report number 287584DF-PTT/04 287584DF-PTT/04

File reference 160520-ND-M5 J25Appraisal EAR-Draft1.0.pdf

ii

M5 Junction 25 Major Scheme Business Case WSP | Parsons BrinckerhoffSomerset County Council Project No 287584DF-PTT/04July 2016 Click here to enter text.

P R O D U C T I O N T E A MCLIENT

Service CommissioningManager, Transport Policy,Somerset County Council

Sunita Mills

WSP | PARSONS BRINCKERHOFF

Author Holly Moon / Neal Dyson

Checker Richard Sweet

Authoriser Marcus Chick

iii

M5 Junction 25 Major Scheme Business Case WSP | Parsons BrinckerhoffSomerset County Council Project No 287584DF-PTT/04

July 2016

TABLE OF CONTENTS1 INTRODUCTION ...........................................................................1

OVERVIEW ..................................................................................................... 11.1

PROPOSED SCHEME .................................................................................... 11.2

2 ECONOMIC ASSESSMENT APPROACH ...................................5

TRANSPORT MODEL .................................................................................... 52.1

FORECAST SCENARIOS ............................................................................... 72.2

STRATEGIC EMPLOYMENT SITE ................................................................. 82.3

HIGHWAYS ENGLAND PROPOSALS ........................................................... 82.4

SUMMARY ................................................................................................... 102.5

OVERVIEW OF ECONOMIC ASSESSMENT ................................................ 112.6

3 ESTIMATION OF COSTS ...........................................................13

SCHEME COSTS AND PROFILE ................................................................. 133.1

LTB FUNDING AND DEVELOPER CONTRIBUTIONS ................................. 143.2

4 ESTIMATION OF BENEFITS .....................................................15

TRAVEL TIME BENEFITS AND VEHICLE OPERATING COSTS ................. 154.1

OTHER MONETISED IMPACTS ................................................................... 184.2

5 ECONOMIC ASSESSMENT RESULTS .....................................19

SCHEME BENEFITS (CORE SCENARIO) .................................................... 195.1

SCHEME BENEFITS (ALTERNATIVE GROWTH SCENARIOS) .................. 235.2

SCHEME BENEFITS (WITH A358 IMPROVEMENT SCHEME) .................... 245.3

ACCIDENT ASSESSMENT RESULTS ......................................................... 265.4

MONETISED ENVIRONMENTAL ASSESSMENT RESULTS ....................... 265.5

OTHER MONETISED IMPACTS ................................................................... 265.6

SUMMARY OF ECONOMIC IMPACTS ......................................................... 275.7

iv


July 2016

BENEFIT COST RATIOS .............................................................................. 315.8

6 CONCLUSIONS ..........................................................................33

v


July 2016

T A B L E STABLE 2-1 BREAKDOWN OF EACH FORECAST SCENARIO ........................................ 10TABLE 3-1 SCHEME COSTS (£000, 2016 Q2 PRICES) .................................................. 13TABLE 3-2 SCHEME COST PROFILE (%)....................................................................... 14TABLE 4-1 ANNUALISATION FACTORS ......................................................................... 15TABLE 4-2 TUBA USER CLASSES ................................................................................. 16TABLE 4-3 SUMMARY OF TUBA WARNINGS (CORE SCENARIO) ................................ 16TABLE 4-4 SCALE OF TUBA WARNINGS RELATING TO TRAVEL TIME ....................... 17TABLE 4-5 SCALE OF TUBA WARNINGS RELATING TO TRAVEL DISTANCE .............. 17TABLE 4-6 SUMMARY OF TUBA SPEED WARNINGS (CORE SCENARIO) ................... 18TABLE 5-1 TRANSPORT BENEFITS BY TRIP PURPOSE (£000, DISCOUNTED TO

2010, IN 2010 PRICES)................................................................... 19TABLE 5-2 TRANSPORT BENEFITS BY VEHICLE TYPE (£000, DISCOUNTED TO

2010, IN 2010 PRICES)................................................................... 19TABLE 5-3 TRANSPORT BENEFITS BY PEAK PERIOD (£000, DISCOUNTED TO

2010, IN 2010 PRICES)................................................................... 20TABLE 5-4 MONETISED TIME BENEFITS BY TRAVEL TIME SAVING (£000,

DISCOUNTED TO 2010, IN 2010 PRICES) ..................................... 21TABLE 5-5 TRAVEL TIME BENEFITS BY SECTOR, DESIGN YEAR 2033 (£000’S) ........ 22TABLE 5-6 DISTRIBUTION OF POSITIVE BENEFITS, DESIGN YEAR 2033 (£000’S)..... 22TABLE 5-7 DISTRIBUTION OF NEGATIVE BENEFITS, DESIGN YEAR 2033 (£000’S) ... 22TABLE 5-8 TRANSPORT BENEFITS BY GROWTH SCENARIO (£000, DISCOUNTED

TO 2010, IN 2010 PRICES) ............................................................. 23TABLE 5-9 TRANSPORT BENEFITS – A358 SENSITIVITY TEST (£000,

DISCOUNTED TO 2010, IN 2010 PRICES) ..................................... 24TABLE 5-10 TRANSPORT BENEFITS – SENSITIVITY TEST (£000, DISCOUNTED TO

2010, IN 2010 PRICES)................................................................... 25TABLE 5-11 ECONOMIC BENEFITS ARISING FROM WIDER IMPACTS (£000,

DISCOUNTED TO 2010, IN 2010 PRICES) ..................................... 26TABLE 5-12 ECONOMIC EFFICIENCY OF THE TRANSPORT SYSTEM ........................ 28TABLE 5-13 PUBLIC ACCOUNTS ................................................................................... 29TABLE 5-14 ANALYSIS OF MONETISED COSTS AND BENEFITS ................................. 30TABLE 5-15 CORE SCENARIO BCRS............................................................................. 31TABLE 5-16 COMPARISON OF BCRS ACROSS ALL SCENARIOS ................................ 31

F I G U R E SFIGURE 1-1 EXISTING LAYOUT AT M5 JUNCTION 25 .................................................... 4FIGURE 2-1 MODELLED AREA......................................................................................... 6FIGURE 2-2 ASSUMED ALIGNMENT OF A358 PROPOSALS .......................................... 9FIGURE 5-1 TOTAL BENEFITS BY YEAR (£000, IN DISCOUNTED TO 2010, IN 2010

PRICES) ......................................................................................... 21

vi


July 2016

A P P E N D I C E SA P P E N D I X A SCHEME PLANS

APPENDIX A-1 M5 JUNCTION 25 FEASIBILITY DESIGNAPPENDIX A-2 M5 JUNCTION 25 INITIAL DESIGN PHASE 1 AND

PHASE 2A P P E N D I X B MODELLED NETWORKS

APPENDIX B-1 WIDER NETWORKAPPENDIX B-2 TAUNTON NETWORK

A P P E N D I X C M5 JUNCTION 25 IMPROVEMENTS – FEASIBILITY COSTSA P P E N D I X D TEE, PA AND AMCB TABLES FOR SENSITIVITY TESTS

APPENDIX D-1 LOW GROWTH SCENARIOAPPENDIX D-2 HIGH GROWTH SCENARIO (CORE + SES)APPENDIX D-3 A358 SCENARIOAPPENDIX D-4 A358 INCLUDING SLIP ROADS SCENARIO

1


July 2016

1 INTRODUCTIONOVERVIEW1.1

1.1.1 WSP | Parsons Brinckerhoff has been commissioned by Somerset County Council (SCC) toupdate the Taunton Strategic Traffic Model, prepare traffic forecasts and carry out an economicappraisal of a major scheme at M5 Junction 25.

1.1.2 A review of the existing model was undertaken in 2014 to assess its suitability for use in theappraisal of major schemes in Taunton1 and it was recommended that the model be updated to a2014 base year and to reflect the current DfT guidance in WebTAG. Therefore, the currentSATURN traffic model has been developed, including new trip matrices based on observed datafrom 2014 and an updated highway network. The development of the base model is described inthe Local Model Validation Report2.

1.1.3 New traffic forecasts have been prepared by pivoting off the validated base model. Themethodology that has been adopted for forecasting was outlined in the Appraisal SpecificationReport (ASR) for the Junction 25 scheme3 and is explained in more detail in the TrafficForecasting Report4.

1.1.4 The purpose of this report is to outline the methodology and results of the economic appraisal ofthe M5 Junction 25 scheme, to support the M5 Junction 25 Major Scheme Business Case(MSBC).

1.1.5 The report contains the following sections:

à Economic Assessment Approach

à Estimation of Costs

à Estimation of Benefits

à Economic Assessment Results

à Summary

PROPOSED SCHEME1.2

BACKGROUND

1.2.1 Junction 25 of the M5 is a key access point to Taunton and also provides a link to the secondstrategic route of the A303 via the A358, making it a key junction within the South West. Thejunction experiences peak hour congestion, with queues frequently extending along the A358 inboth directions and occasionally backing up onto the mainline M5.

1 TSTM3 Model Review, Parsons Brinckerhoff (August 2014)2 M5 Junction 25 Local Model Validation Report, WSP Parsons Brinckerhoff (April 2016)3 M5 Junction 25 Appraisal Specification Report, Parsons Brinckerhoff (November 2015)4 M5 Junction 25 Traffic Forecasting Report, Parsons Brinckerhoff (May 2016)

2


July 2016

1.2.2 There are two employment sites (Blackbrook and Hankridge) located close to the junction and theproximity of the M5 makes them attractive to businesses to locate there. The proposal for a newstrategic employment site, generating up to 3,000 jobs, to be located to the east of Junction 25 atHenlade has been identified by Taunton Deane Borough Council’s Site Allocation SupplementaryPlanning Document5 evidence base work. In addition, Taunton is also forecast to deliver 13,000dwellings as part of Taunton Deane’s Core Strategy6, which will also place considerable pressureon the junction. Therefore it is fundamental that Junction 25 is upgraded to cope with thisprojected increase in demand.

1.2.3 The M5 Junction 25 scheme objectives are identified below:

1. Support the economy in Taunton by facilitating the delivery of employment and residentialdevelopment.

2. Reduce weekday peak hour traffic congestion at Junction 25 and improve access to Tauntonand the motorway.

3. Improve accessibility to Taunton and future development areas for pedestrians and cyclists.

PROPOSED SCHEME

1.2.4 Figure 1-1 overleaf shows the existing layout of the junction and immediate surrounding areaincluding the Gateway Park and Ride site. The drawings in Appendix A have been provided bySCC and show the proposed scheme. This includes improvements to Junction 25 itself (shown inAppendix A-1), plus new highway links to the east of the junction which tie in to form a sixth armat the motorway junction and provide revised access to the Park and Ride site (shown inAppendix A-2).

1.2.5 The proposed works to the motorway junction include extension and widening of the circulatorycarriageway (in order to accommodate a sixth arm), widening of the southbound off-slip andsignalisation of all arms except for Blackbrook Park.

1.2.6 To the east of the junction, the existing A358 will become eastbound-only between Junction 25and Ruishton Lane (alleviating the existing bottleneck over the watercourse on the exit) whilstwestbound traffic will be redirected along a new route which passes along the western edge of theexisting Park and Ride site and along a new link into Junction 25. A roundabout junction isprovided along this new westbound route and would form the access to a proposed largedevelopment site that would be unlocked by the scheme.

1.2.7 Improvements to the A358 corridor between the A303 and M5 (currently being progressed byHighways England) would include a bypass of Henlade village which may tie in with the proposedscheme at this roundabout. If this were to be implemented (or if the employment site comesforward) the new link at Junction 25 would need to be upgraded to serve both east andwestbound flows. In this situation, the existing A358 arm would only be used for local access (forexample to Henlade, Creech St Michael and Ruishton) and for access by Park and Ride buses.This additional improvement is separate to the scheme being considered in this appraisal.

5http://consultldf.tauntondeane.gov.uk/portal/sadmpp/sadmp-po

6http://www.tauntondeane.gov.uk/irj/public/council/futureplans/futureplan?rid=/wpccontent/Sites/TDBC/Web%20Pages/Council/Future%20plans/Core%20Strategy

3


July 2016

CONSTRUCTION

1.2.8 The new section of road between the existing A358 and J25 which passes through the existingPark & Ride facility, including the new roundabout and the section of dual carriageway down toJ25 will be constructed by accessing off of the existing A358 through the Park & Ride Site.Therefore the construction of this section of the scheme will require very little traffic managementon the existing A358 and therefore delays during construction will be minimal.

1.2.9 Construction of the structures across the existing watercourses to the south of J25 will beundertaken from the south with access gained through the Park & Ride facility and the newsection of carriageway.

1.2.10 The works to elongate and provide additional traffic lanes and installation of traffic signals at J25will largely be undertaken utilising lane closures, which will be implemented outside of peak hours(probably overnight) to minimise disruption to traffic flows. Overnight closures of the motorway sliproads will be required during some construction operations. These will be coordinated withHighways England to minimise impact on M5 traffic flows.

MAINTENANCE

1.2.11 Future maintenance of Junction 25 will be less onerous than the existing situation because therewill be additional carriageway width available and therefore it will be possible to carry out amajority of routine maintenance operations through overnight lane closures.

1.2.12 Maintenance of the new section of dual carriageway, the roundabout and the new carriagewaythrough the Park & Ride site would be undertaken through lane closures outside of peak hours.

4


July 2016

Figure 1-1 Existing layout at M5 Junction 25

5


July 2016

2 ECONOMIC ASSESSMENT APPROACHTRANSPORT MODEL2.1

OVERVIEW

2.1.1 This section provides an overview of the SATURN transport model that has been developed toappraise the scheme. The model is a highway only model which includes trip distribution and tripfrequency demand response in the future years. The Local Model Validation Report and theTraffic Forecasting Report fully detail the development of the base year model and trafficforecasts.

2.1.2 These traffic forecasts have been used to assess the economic impact of the Scheme, inaccordance with WebTAG. The forecasts from the model have also fed into the environmentaland social impact assessments of the Scheme. The modelling follows the methodology detailed inthe Appraisal Specification Report.

MODEL COVERAGE

2.1.3 The fully modelled area covers all of Taunton and includes the A358 route as far as the A303.Figure 2-1 shows the extent of the Fully Modelled Area and also indicates the Area of DetailedModelling. The external area of the model covers the whole of mainland UK but only representstrips heading to, from or through the fully modelled area. Appendix B shows the model network atvarious scales.

MODELLED YEARS AND TIME PERIODS

2.1.4 The base model was built and validated using data collected during October and November 2014and therefore represents an average weekday during these months.

2.1.5 Consistent with the ASR, two future years have been modelled in line with the anticipated openingyear of the Junction 25 scheme and a ‘design year’ for the economic appraisal:

à Year 1: 2018 opening year

à Year 2: 2033 design year (opening +15 years)

2.1.6 For the purpose of appraising the scheme, three time periods have been modelled. Theseinclude AM and PM peak hours (08:00-09:00 and 17:00-18:00 respectively) and an average inter-peak hour (between 10:00-16:00). The peak hours were determined by analysing annual trafficcount data throughout the modelled area, including a traffic count on the Toneway Corridor closeto Junction 25.

2.1.7 An off-peak hour has not been modelled because it is not expected that the scheme wouldproduce significant benefits during the evening and overnight, as detailed in Section 3.5.6 of theAppraisal Specification Report. Similarly, weekend periods have not been modelled because it isassumed that the scheme would not generate significant benefits at these times.

6


July 2016

Figure 2-1 Modelled area

DEMAND SEGMENTATION

2.1.8 The model’s trip matrices are split into the following user classes (UCs), in line with thesegmentation used in WebTAG:

à UC1 – Car commute

à UC2 – Car employers business

à UC3 – Car other

à UC4 – Light Goods Vehicle (LGV)

à UC5 – Heavy Goods Vehicle (HGV)

2.1.9 Section 4.1 outlines how these user classes have been allocated to TUBA user classes.

BASE YEAR MODEL CALIBRATION AND VALIDATION

2.1.10 The SATURN model is a strong representation of traffic flows across the area of detailedmodelling and has been calibrated in detail using observed turning flows at key junctions. Inparticular, the model is a very good representation of the turning flows at Junction 25 and at thejunctions along the Toneway corridor including Heron Gate roundabout, Creech Castle andObridge roundabout. This provides confidence that the model will be suitable for use in theappraisal of the Junction 25 and Toneway schemes and could be used for wider strategicmodelling purposes if required.

7


July 2016

2.1.11 Given that observed journey times in the modelled area showed significant variability, it isconsidered that the model also provides a good representation of traffic speeds and journeytimes. In particular, the model replicates the shape of the observed journey time profiles and thisindicates that the model is able to recreate delays in correct locations and that there are very few‘false’ delays which might influence the assignment. However, the modelled journey time over thetotal length of some routes was shown to be lower than the average of observed times and, whilstthis is not considered to be a significant issue, it may reduce modelled scheme benefits.

2.1.12 Specifically in terms of its suitability for use in developing forecasts for the appraisal of Junction25, the main conclusions are as follows:

à The model is a good representation of traffic flows at Junction 25, in terms of overalltraffic throughput and individual turning movements. On this basis it is likely that themodel will produce robust forecasts of traffic flow at this junction in the future year.

à The model converges well in the future year scenarios and therefore the economicappraisal results are unlikely to be adversely affected by convergence ‘noise’.

à The model is also a good representation of the junctions along the Toneway corridorincluding Heron Gate, Creech Castle and Obridge Roundabout.

à The model is not able to reflect some of the more extreme delays that were recorded onthe approaches to Junction 25 but is otherwise a good representation of the traffic speedsand delays in both directions along the A358 corridor. Potentially the model may under-estimate peak hour delays at the junction in future years, and therefore under-estimatethe benefits associated with the scheme.

à The model is able to replicate the amount of traffic using Haydon Lane and South Road toaccess Taunton from the south instead of the A358 via Junction 25. From the dataavailable, the model appears to have the right amount of traffic using these routes andthe journey times along them are also a reasonable fit with observed times.

FORECAST SCENARIOS2.2

2.2.1 Through discussion with SCC and the Independent Technical Advisor (ITA) for the Heart of theSouth West Local Transport Board (LTB) it was agreed that the following forecast scenarioswould be required to fully appraise the Junction 25 scheme and the associated uncertaintiesaround future developments and highway infrastructure.

· Core scenario – this is a forecast which is constrained to TEMPRO and is the best availableprediction of likely outcomes.

· Low growth scenario – this is a reduced growth forecast based on the WebTAG approachfor uniformly factoring down traffic growth in the matrix for the Core scenario.

· High growth scenario – this is equivalent to the growth in the core scenario plus additionaltraffic demand associated with the Strategic Employment Site at Junction 25.

· A358 – this includes the Highways England scheme to create a dual carriageway linkbetween the A303 and the M5 at Junction 25.

· A358 plus south facing slips – this includes the Highways England scheme to create a dualcarriageway link between the A303 and the M5 at Junction 25 with a free flow connection tothe M5 south of Junction 25 and would be expected to remove traffic demand from Junction25.

8


July 2016

STRATEGIC EMPLOYMENT SITE2.3

2.3.1 In addition to the developments that are included in the core scenario, a further largedevelopment site is proposed adjacent to Junction 25. This site is intended to be a large non-residential development which would incorporate a mix of office and industrial land uses. It wasnot considered to be certain enough to include within the core scenario but, given its proximityand likely impact on Junction 25 if it were to be built, it has been agreed with the ITA that it shouldbe considered as a sensitivity test.

2.3.2 A report examining the commercial potential of the site7 estimates that it may generate in theorder of 1,000 vehicles (two way) during each of the peak hours with a majority of this trafficpassing through Junction 25.

2.3.3 It is not expected that the Strategic Employment Site will be constructed to any degree by the firstappraisal year of 2018, so this scenario has only been modelled in the second appraisal year of2033.

HIGHWAYS ENGLAND PROPOSALS2.4

BACKGROUND

2.4.1 As part of the Road Investment Strategy, Highways England is planning to create a dualcarriageway link between the A303 and the M5 at Junction 25. Given that this scheme is at anearly stage and not yet within the formal planning process it is not considered that it has a highenough level of certainty to be included in the core forecast scenario. However, as it is likely tohave an effect on traffic demand at Junction 25, it is necessary to understand the potential impactit might have on Junction 25 scheme benefits and therefore has also been explored as asensitivity test.

2.4.2 The proposed alignment or standard of the route is not known at this stage, however it has beenassumed that the A358 scheme will involve widening of the existing carriageway betweenIlminster and Henlade (where the road is already wide and does not pass through any towns orvillages) to dual carriageway standard and would include a bypass of Henlade village to thesouth, crossing Stoke Road via an overbridge. Figure 2-2 below illustrates the assumedalignment.

7 M5 Junction 25: Value of a Second Strategic Employment Site, Peter Brett Associates (March 2014)

9


July 2016

Figure 2-2 Assumed alignment of A358 proposals

2.4.3 With the proposed scheme at Junction 25 also in place, the A358 bypass of Henlade couldfeasibly connect into the new roundabout junction south and west of the existing Park and Ridesite. This would ensure that the employment site (for which this new junction also providesaccess) has a direct connection to the new A358 route and would enable the majority of trafficfrom the east to use the new arm at Junction 25.

ASSUMPTIONS

2.4.4 It has been agreed with the ITA that, for the purpose of the appraisal of the Junction 25 schemewhere proposals for the A358 scheme are not known in detail, it will be assumed that a similarscheme (i.e. a signalised sixth arm at Junction 25) would not be provided as part of the A358scheme for the Do Minimum scenario. This is an important assumption because it has a materialeffect on the predicted scheme benefits with both schemes in place.

2.4.5 It has not been possible for the traffic modelling of the A358 scheme to include widerreassignment of traffic between the M5 and A303 due to the coverage of the traffic model.Potentially modelled traffic on the A358 could have been artificially increased to replicate a widerreassignment effect, however a manual adjustment was not applied given the difficulties ingenerating robust assumptions about the level of increase and potential distribution for newlyintroduced trips without access to a larger strategic model. It is understood that the traffic modelbeing developed for the A358 scheme is not yet at a stage where it is suitable for providingforecasts.

ALTERNATIVE LAYOUT (SLIP ROADS)

2.4.6 It is understood that Highways England may decide to provide a direct, free flowing link for thenew A358 route onto the M5 south of Junction 25. This would be likely to remove a proportion oftraffic from Junction 25 and therefore has been explored through a further sensitivity test as it mayreduce the economic benefit of the Junction 25 scheme.

10


July 2016

2.4.7 It is expected that the A358 scheme will be constructed between the first appraisal year of 2018and the final appraisal year of 2033, however in the absence of an interim year it will only bepossible to include the scheme in the model from 2033. As the free flow links may remove trafficand reduce scheme benefits, only modelling them from 2033 onwards is likely to lead to anoverestimate of economic benefit. Rather than modelling an intermediate appraisal year it wasdecided that a more proportionate approach would be to remove all scheme benefits for theperiod over which the slip roads would be open but not included in the model.

2.4.8 In summary, for the A358 sensitivity test including slip roads benefits have been derived asfollows:

à 2018 to 2025 - Benefits from the Core Scenario economic assessment

It is assumed that the A358 scheme with free flow slips opens in 2025 so the benefitsfrom the core scenario will be applicable from 2018 until 2025.

à 2025 to 2033 - No economic benefits

No benefits have been assumed for these years. This is likely to be an underestimate ofthe actual economic benefits during these years.

à 2033 onwards - Benefits from the A358 free flow slips sensitivity test economicassessment

SUMMARY2.5

2.5.1 Table 2-1 summarises the individual elements of demand and supply that are included in each ofthe scenarios assessed. As it is not expected that the A358 or Strategic Employment Site will beconstructed by the first appraisal year (2018) these have only been modelled in the secondappraisal year (2033).

2.5.2 For each of the scenarios listed, a Do Minimum and Do Something scenario has been modelledwhere the only difference is the inclusion of the Junction 25 scheme in the network (plus anydemand change arising from the modelling of demand responses).

Table 2-1 Breakdown of each forecast scenario

SCENARIO

APPLICABLEFUTURE YEARS

SUPPLY DEMAND

2018 2033CommittedSchemes

(e.g. NIDR)

HE A358Scheme

A358 SouthFacing Slips

Coregrowthforecast

Lowgrowthforecast

StrategicEmployment

Site

Core ü ü ü ü

Low Growth ü ü ü ü

High Growth ü ü ü ü

A358 ü ü ü ü

A358+FF ü ü ü ü ü

11


July 2016

OVERVIEW OF ECONOMIC ASSESSMENT2.6

2.6.1 The economic appraisal undertaken for each scheme option includes monetisation of thefollowing:

à Travel time benefits

à Vehicle operating costs

à Accident savings

à Noise and greenhouse gases

2.6.2 An overview of the assessment of each of these impacts is provided below, with further detailsprovided in Section 4.

2.6.3 Construction and maintenance impacts have not been assessed because it is considered that theimpact of construction and additional maintenance will be small in comparison to the overall costsand benefits of the scheme (see section 1.2).

TRAVEL TIME BENEFITS AND VEHICLE OPERATING COSTS

2.6.4 Travel time benefits and the impact on vehicle operating costs have been assessed using TUBA(Transport Users Benefit Appraisal) software over a standard appraisal period of 60 years.

2.6.5 TUBA calculates travel time benefits due to the scheme by comparing the travel costs betweenthe Do Minimum and Do Something assignments. The time saved is then monetised and a benefitcalculated. The value of time varies based upon the purpose of the trip (e.g. an employer’sbusiness trip has a greater value than a personal trip). The value of time is expected to increasein the future due to the increase in general wages and the growth in the economy. The economicsinput file encompasses parameters, definitions, growth rates, changes and other factors that areconsistent with the TAG Data Book, December 2015.

2.6.6 The vehicle operating costs are calculated in a similar way to the travel time benefits except thatdistance and time savings are used.

ACCIDENTS

2.6.7 As set out in WebTAG Unit A4.1, Section 2.3, an appraisal of accident savings has beenundertaken using the COBA-LT Spreadsheet Tool8. This workbook uses standard assumedaccident rates for different types of link and junction and applies them to link flows extracted fromthe traffic model. COBA-LT has been used to derive safety benefits only.

2.6.8 Full details of the methodology and results are given in the Social Impact Appraisal Report9 andare not discussed here.

GREENHOUSE GASES

2.6.9 The TUBA program includes an assessment of the change in greenhouse gases produced byimplementing the scheme. The amount of greenhouse gases in each scenario is calculated usingthe trip information that has been extracted from the SATURN models, and monetised in TUBA.

8 https://www.gov.uk/government/publications/cobalt-software-and-user-manuals9 M5 Junction 25 Social Impact Appraisal Report (April 2016).

12


July 2016

2.6.10 The greenhouse gas assessed, where the only transport mode is road, is carbon dioxide. TheTUBA program has default values for the amount of carbon produced per litre of fuel and alsouses default monetary values for carbon dioxide produced.

2.6.11 The amount of benefit is calculated for the modelled years. The carbon benefits are thencalculated over the 60 year appraisal period using the same method that is used for all travel timeand vehicle operating cost benefits.

2.6.12 The assessment takes into account the future fuel efficiency of vehicles, which is predicted toincrease, and also the change in the cost of carbon.

NOISE

2.6.13 The monetary valuation is based on the estimation of the number of Disability-Adjusted Life Years(DALYs) lost (or gained) under each impact pathway, taking into account a value of £60,000 perDALY. This part of the appraisal is based on the study ‘Environmental noise: Valuing impacts onsleep disturbance, annoyance, hypertension, productivity and quiet (Defra, 2014) and themodelling tool. The TAG Data Book Table A3.1 shows the annual value of the impact of a 1 dBchange in exposure at noise levels between LAeq,16h 45 to 81 dB. Values for sleep disturbance aregiven from Lnight 45 to 81 dB.

2.6.14 The methodology is fully detailed in the WebTAG Environmental Appraisal Summary Report10 andis not discussed further here.

OTHER MONETISED IMPACTS

2.6.15 WebTAG (Unit A1.1 Section 1) lists impacts that can be monetised but are not normally reportedin the Analysis of Monetised Costs and Benefits (AMCB) Table or the Initial Benefit to Cost Ratio(BCR). The DfT11 advises that these can be applied to an ‘adjusted BCR’.

2.6.16 For this appraisal, the following additional impacts have been monetised for Junction 25improvements as outlined in the ASR:

à Wider Impacts – output change in imperfectly competitive market.

10 M5 Junction 25 Environmental Appraisal Summary Report (April 2016)11 Value for Money Assessment: Advice Note for Local Transport Decision Makers (December 2013)https://www.gov.uk/government/publications/value-for-money-advice-for-local-transport-decision-makers

13


July 2016

3 ESTIMATION OF COSTSSCHEME COSTS AND PROFILE3.1

3.1.1 Scheme cost estimates have been prepared by AECOM and agreed by SCC. The derivation ofthe scheme costs is fully detailed in Appendix C in the M5 Junction 25 Improvements FeasibilityCosts Report (30 March 2016). This report assumes the following:

à Costs are in second quarter 2016 price base.

à No allowance for inflation has been included.

à No costs have been estimated for land or landscaping.

à There is no allowance for supervision of the works.

3.1.2 The following assumptions have been made to costs received from AECOM before input toTUBA:

à The Construction cost is assumed to be the ‘Total Building Costs’ in the AECOM report.

à Design costs were not included in the AECOM cost estimate but these have beenassumed to be 10% of the Construction cost. It is therefore assumed that the Preparationcost is the sum of Professional fees, Local Authority charges, surveys, site investigationand the assumed design costs.

à

à The risk cost is assumed to be the ‘project contingency’ figure outlined in the AECOMreport and has been split proportionally across the Construction and Preparation costs.

à Optimism Bias has been added as 44% of the total cost including risk.

à A cost profile has not been provided so Construction costs have been divided equallyacross 2017 and 2018 (based on a scheme opening year of 2018). All Preparation costsare assumed to be incurred in 2017.

3.1.3 Table 3-1 and Table 3-2 show the scheme costs and cost profile as input to TUBA.

Table 3-1 Scheme Costs (£000, 2016 Q2 PRICES)

1 – SCHEME COST2 – SCHEME COSTINCLUDING RISK

3 – TUBA INPUT – SCHEME COSTINCLUDING RISK AND 44%

OPTIMISM BIAS

Construction 10,020.8 10,954.9 15,775.1

Land 0.0 0.0 0.0

Preparation 1,589.5 1,737.6 2,502.2

Supervision 0.0 0.0 0.0

TOTAL 11,610.3 12,692.5 18,277.2

14


July 2016

Table 3-2 Scheme Cost Profile (%)

YEAR PREPARATION SUPERVISION CONSTRUCTION LAND

2017 100% 0% 50% 0%

2018 0% 0% 50% 0%

LTB FUNDING AND DEVELOPER CONTRIBUTIONS3.2

3.2.1 It is understood that SCC is seeking £12.9 million of funding from the LTB and therefore costsinput into TUBA have been divided into Central and Local government as follows:

à Central Government (LTB) - £12.9 million (71% total scheme cost)

à Local Government (SCC) - £5.4 million (29% total scheme cost)

3.2.2 SCC has confirmed that developer contributions in the amount of £3 million will be available tofund the scheme. Within WebTAG, developer contributions are incorporated as a (negative)‘benefit’ rather than as a ‘cost’ because costs are recorded as those which are paid for by thepublic sector. Using this method the Present Value Cost (PVC) output from TUBA is £12,730,000(discounted to 2010, in 2010 prices).

3.2.3 The ITA has indicated that any developer contributions should be included as a ‘cost’ so that theBCR can be compared with other schemes. Using the method, where developer contributions arenot incorporated into the economic assessment as a (negative) economic benefit, the PresentValue Cost (PVC) is £15,223,000 (discounted to 2010, in 2010 prices).

15


July 2016

4 ESTIMATION OF BENEFITSTRAVEL TIME BENEFITS AND VEHICLE OPERATING COSTS4.1

OVERVIEW

4.1.1 Travel time benefits and vehicle operating costs have been calculated using TUBA version 1.9.6.The parameters used in the economic assessment have been taken from economics file 1.9.6which is informed by the TAG Data Book, December 2015.

4.1.2 The economic assessment assumes the opening year for the scheme will be 2018 and is basedon a 60 year appraisal period. A scheme design year of 2033 (opening year plus fifteen years)has been included but it is assumed that there is no growth in benefits after the design year.

ANNUALISATION FACTORS

4.1.3 Annualisation factors have been calculated in order to expand the user benefits for each modelledtime period to produce scheme benefits over each year. Traffic count data from an ATC onToneway for 2015 has been used to determine the AM and PM peak hour to peak period factors.

4.1.4 Benefits have not been calculated for the overnight time period (7pm – 7am), weekends or bankholidays.

Table 4-1 Annualisation Factors

TUBA TIME SLICE TRAFFIC MODEL TIME PERIODHOURS PER

DAYDAYS PER YEAR

ANNUALISATIONFACTOR

AM Peak (8-9 weekdays) 8:00 – 9:00 2.8 253 708

Interpeak (10-16 weekdays) Average hour 10:00 – 16:00 6.0 253 1,518

PM Peak (17-18 weekdays) 17:00 – 18:00 2.9 253 746

Total Hours Modelled in TUBA 3,036

Total Hours in a Year 8,760

16


July 2016

USER CLASSES

4.1.5 The modelled user classes have been converted to the TUBA user classes shown in Table 4-2.

Table 4-2 TUBA User Classes

TUBA USERCLASS

TUBAVEHICLE CLASS

TUBAPURPOSE

TRAFFIC MODELUSER CLASS

FACTOR APPLIED TO TRIPMATRIX

11 Car

1 Business 1 Car Commute 12 2 Commute 2 Car Employers Business 13 3 Other 3 Car Other 14 2 LGV Personal All

4 LGVs0.12

5 3 LGV Freight All 0.886 4 OGV 1 All

5 HGVs0.34

7 5 OGV 2 All 0.12

4.1.6 The factors applied to the LGV trip matrix to convert to LGV personal and LGV freight are defaultsplits from Table A1.3.4 of the TAG Data Book.

4.1.7 The factors applied to the OGV trip matrix to split into OGV1 and OGV2 are derived from themanual classified counts associated with the Roadside Interview Surveys undertaken to developthe traffic model. The factors applied to the HGV matrix includes a conversion from PCUs (asmodelled in the SATURN traffic model) to vehicles.

CHECKS OF ECONOMIC APPRAISAL RESULTS

4.1.8 An analysis of the warnings that are output from TUBA has been undertaken to check that thechanges in the model which generate economic benefits are reasonable. Table 4-3 summarisesthe warnings output from TUBA for the core scenario. This shows that there are relatively fewserious warnings and that the warnings only refer to a very small proportion of the trips in themodel (less than 1%).

Table 4-3 Summary of TUBA warnings (core scenario)

WARNINGSSERIOUS

WARNINGSWARNINGS

NO OF TRIPSAFFECTED (DS)

PROPORTION OFTOTAL TRIPS

Ratio of DM to DS travel time lowerthan limit 17 1,783 88 0.1%

Ratio of DM to DS travel time higherthan limit 3 6,262 391 0.2%

Ratio of DM to DS travel distancelower than limit 64 1,484 89 0.1%

Ratio of DM to DS travel distancehigher than limit 17 3,524 84 0.1%

All 101 13,053 652 0.5%

17


July 2016

4.1.9 A majority of the warnings refer to a reduction in travel time due to the scheme (i.e. ratio of traveltime higher than limit). As discussed in the Forecasting Report, the scheme (as modelled)significantly reduces delay at Junction 25 so warnings of this type are to be expected. Table 4-4below shows the scale of changes that are being higlighted by warnings relating to travel time. Amajority of these warnings refer to time savings of between 5 and 10 minutes. Whilst this doesappear to indicate degree of change above that which might be expected, it relates to a very smallproprtion of OD pairs in the model (0.4%) and a very small proportion of the total trips in thesystem (0.2%), and therefore it is unlikely that they are indicative of an issue with the appraisalresults.

Table 4-4 Scale of TUBA warnings relating to travel time

CHANGE IN OD TIME DUE TO SCHEME (ALL SUB-MODES, TIME PERIODS, YEARS)

< -10mins

-10 to -5mins

-5 to -2mins

-2 to 0mins

0 to 2mins

2 to 5mins

5 to 10mins

> 10 mins

Warnings 17 4,058 1,559 628 1,068 715 0 0

OD Pairs 6 298 95 52 81 64 0 0

Trips 3 298 84 6 30 58 0 0

4.1.10 Table 4-5 shows the scale of change from warnings relating to travel distance. A majority ofthese warnings refer to large reductions in distance, particularly change of up to 10 kilometres.The model does indicate that implementing the scheme would likely draw traffic back off longerdistance routes and therefore it may be reasonable to expect warnings of this nature. However,similar to the warnings relating to changes in travel time, whilst these indicate some largechanges in assigned distance, they only relate to a very small proportion of the overall trips in thesystem and therefore are unlikely to have a signifcant bearing on the results of the appraisal.

Table 4-5 Scale of TUBA warnings relating to travel distance

CHANGE IN OD DISTANCE DUE TO SCHEME (ALL SUB-MODES, TIME PERIODS, YEARS)

< -15 km -15 to -10km

-10 to -5km

-5 to 0 km 0 to 5 km 5 to 10km

10 to 15km

> 15 km

Warnings 6 571 1,449 1,498 1,057 301 122 4

OD Pairs 3 165 395 329 238 127 60 3

Trips 1 21 27 36 45 8 36 0

18


July 2016

4.1.11 Table 4-6 below shows a summary of TUBA warnings related to speeds. There are a largenumber of trips which have an average origin-destination speed greater than the TUBA limit(which is understood to be 112 kph) however in all cases these trips are motorway trips withspeeds that are only fractionally above this limit (maximum speed recorded in output was 112.2kph) and therefore not symptomatic of an issue in the model.

4.1.12 The warnings referring to average origin-destination speeds lower than the TUBA limit relate to avery small proportion of the total trips which are of relatively short distance and pass throughcongested junctions where there are large delays.

Table 4-6 Summary of TUBA speed warnings (core scenario)

WARNING NO OF WARNINGS NO OF TRIPS

DM speeds less than limit 1,656 57

DM speeds greater than limit 2,316 4,474

DS speeds less than limit 1,596 25

DS speeds greater than limit 2,133 4,049

4.1.13 Beyond analysis of TUBA warnings, a number of other checks have been undertaken tounderstand and verify the traffic forecasts and are discussed in more detail in the ForecastingReport:

à Analysis of traffic flows on links surrounding Junction 25 – these help to understand thetraffic forecasts and confirm the amount of traffic likely to be affected by the scheme.

à Analysis of impact to travel time for journeys made through Junction 25 via the mainroutes from the motorway and A358.

à Analysis of traffic flows, delay and V/C% at Junction 25 with and without the scheme –this shows how the delay and capacity at the junction changes as a result of the schemeand shows how a majority of travel time benefits arise.

OTHER MONETISED IMPACTS4.2

WIDER IMPACTS

4.2.1 WebTAG (Unit A2.1) indicates that a simplified approach can be taken to measuring the outputchange in imperfectly competitive markets (which results because increases in the output ofgoods and services are valued more highly by consumers than the cost of producing that output).The approach is simply to calculate an uplift of 10% to business user benefits.

4.2.2 Other wider impacts were either ruled out in the ASR or, as in the case of Labour Supply Impacts,it is not considered that there is a sufficient step-change in commuting generalised cost to merit afull assessment (see particularly Table 5-1 and Table 5-4, which demonstrate that only a smallproportion of benefits accrue to commuting journeys where more than five minutes is saved).

19


July 2016

5 ECONOMIC ASSESSMENT RESULTSSCHEME BENEFITS (CORE SCENARIO)5.1

BENEFITS BY PURPOSE, VEHICLE TYPE AND TIME PERIOD

5.1.1 Table 5-1 shows the total benefits over the 60 year appraisal period split into benefit type and splitbetween trip purposes.

Table 5-1 Transport Benefits by Trip Purpose (£000, discounted to 2010, in 2010 prices)

SCENARIO PURPOSE TRAVEL TIME VOC FUEL VOC NON-FUEL INDIRECT TAX TOTAL

Core

Business 79,875 -6,378 4,000 3,941 81,438

Commuting 23,340 750 -805 52 23,337

Other 55,938 -1,943 -4,900 4,025 53,120

Total 159,153 -7,571 -1,705 8,018 157,895

5.1.2 The majority of benefits created by the scheme are travel time benefits, and this is expected giventhe extent to which the scheme (as modelled) reduces delays at Junction 25.

5.1.3 Overall the scheme generates negative vehicle operating cost benefits, however these are verysmall compared to level of travel time benefit (amounting to approximately 6% in absolute terms)and therefore do not have a significant impact to the overall economic benefit generated by thescheme. It is likely that these negative benefits are due to the increased distance that traffic musttravel along the new link road in the scheme which is approximately 300 metres longer than theequivalent route on the existing network.

5.1.4 It is of note that non-fuel vehicle operating costs show a benefit for business trips and this is likelyto be related to reassignment of traffic to longer alternative routes than those which pass throughJunction 25 and incur significant delays in the Do Minimum scenario. Business trips (which havea highest value of time and are therefore most sensitive to delays) are the most likely to reassignto alternative routes and then return to shorter routes with the scheme in place, and this may bethe reason why they incur higher non-fuel vehicle operating cost benefits than other purposes.

5.1.5 Table 5-2 shows the breakdown of benefits over the 60 year appraisal period split into trippurposes. As would be expected, the majority of benefits (approximately 75%) are generated bycar trips and this is consistent with the proportion of the trip matrix that is made up of cars.

Table 5-2 Transport Benefits by Vehicle Type (£000, discounted to 2010, in 2010 prices)

SCENARIO PURPOSE TRAVEL TIME VOC FUEL VOC NON-FUEL INDIRECT TAX TOTAL

Core

Car 117,789 -1,515 -4,485 4,802 116,591

LGV Personal 1,887 -445 -8 238 1,672

LGV Freight 22,942 -3,237 401 1,718 21,824

OGV1 12,222 -2,120 1,421 1,125 12,648

OGV2 4,312 -254 966 135 5,159

Total 159,153 -7,571 -1,705 8,018 157,895

20


July 2016

5.1.6 Table 5-3 summarises the total benefit over the appraisal period by time period. The AM peakperiod contributes the most benefit (approximately 38%) but is broadly similar to the other timeperiods (which both contribute around 30% each). Benefits generated in the PM peak are likely tobe lower than the AM because of certain issues which are specific to the PM peak. For example,the model shows that there would be an increase in delay due to the scheme at the BlackbrookPark intersection of Junction 25, and that this is highest in the PM peak when there a largenumber of departures from the business park. This traffic is affected by an increase in the volumeof circulating traffic due to the scheme.

5.1.7 Inter peak benefits are similar to PM peak benefits, but it is noted that the inter peak periodrepresents a much higher proportion of the number of hours annually, and therefore might beexpected to reach a similar level of benefit to the peak hours.

Table 5-3 Transport Benefits by Peak Period (£000, discounted to 2010, in 2010 prices)

SCENARIO TIME PERIOD TRAVEL TIME VOC FUEL VOC NON-FUEL INDIRECT TAX TOTAL

Core

AM 60,990 -2,767 -1,110 3,400 60,513

IP 48,289 -1,631 -185 2,091 48,564

PM 49,874 -3,173 -410 2,527 48,818

Total 159,153 -7,571 -1,705 8,018 157,895

PROFILE OF BENEFITS OVER 60 YEAR APPRAISAL PERIOD

5.1.8 Figure 5-1 illustrates scheme benefits for each individual year over the 60 year appraisal period.This shows an increase in economic benefits between the two modelled years (2018 and 2033)and then a gradual decline from the final model years onwards as no further growth is applied butbenefits are still subject to inflation and discounting.

21


July 2016

Figure 5-1 Total Benefits by Year (£000, in discounted to 2010, in 2010 prices)

BENEFITS BY TRAVEL TIME SAVING

5.1.9 Table 5-4 shows the travel time benefit split into the size of time saving.

Table 5-4 Monetised Time Benefits by Travel Time Saving (£000, discounted to 2010, in 2010 prices)

SCENARIO PURPOSE 0 TO 2MIN 2 TO 5MIN > 5MIN

Core

Business 15,857 28,241 35,778

Commuting and Other 10,535 33,518 35,225

All 29,221(17%)

24,353(39%)

51,418(45%)

5.1.10 The table shows that almost half of the travel time benefits arise from changes in travel time inexcess of 5 minutes and indicates that the scheme is having a tangible impact to individualjourneys, rather than deriving a majority of benefits from lots of small time savings across thenetwork.

BENEFITS BY SECTOR

5.1.11 The distribution of travel time benefits is presented using a simple sector system which isolateskey movements within the model as follows:

à Taunton

à A358/A303

0

500

1000

1500

2000

2500

3000

3500

400020

1820

2020

2220

2420

2620

2820

3020

3220

3420

3620

3820

4020

4220

4420

4620

4820

5020

5220

5420

5620

5820

6020

6220

6420

6620

6820

7020

7220

7420

76

Tota

lBen

efits

(£00

0)

Year

Total Benefits by Year

22


July 2016

à Wellington

à Bridgwater/North Petherton

à Exmoor/Quantocks

à M5 North

à M5 South

5.1.12 Table 5-5 below shows the total travel time benefit by sector for the scheme design year 2033and Table 5-6 and Table 5-7 show the distribution of positive and negative benefits.

Table 5-5 Travel time benefits by sector, design year 2033 (£000’s)

NO. SECTOR NAME 1 2 3 4 5 6 7 T1 Taunton -274 664 198 256 54 360 396 1,6552 A358/A303 817 -35 205 257 126 410 250 2,0303 Wellington -12 29 5 6 2 33 37 1004 Bridgwater -199 32 -24 21 -7 13 29 -1355 Exmoor/Quantocks -75 28 7 7 1 16 13 -46 M5 North -124 12 -39 0 -12 0 -3 -667 M5 South -146 -6 -47 20 -12 101 0 -89

Total -12 723 304 566 152 934 723 3,391

Table 5-6 – Distribution of positive benefits, design year 2033 (£000’s)

NO. SECTOR NAME 1 2 3 4 5 6 7 T1 Taunton 15% 5% 6% 1% 8% 9% 44%2 A358/A303 19% 5% 6% 3% 9% 6% 47%3 Wellington 1% 1% 1% 3%4 Bridgwater 1% 1% 2%5 Exmoor/Quantocks 1% 2%6 M5 North 0%7 M5 South 2% 3%

Total 19% 17% 10% 13% 4% 20% 16%

Table 5-7 – Distribution of negative benefits, design year 2033 (£000’s)

NO. SECTOR NAME 1 2 3 4 5 6 7 T

1 Taunton 27% 27%

2 A358/A303 3% 3%

3 Wellington 1% 1%

4 Bridgwater 20% 2% 1% 23%

5 Exmoor/Quantocks 7% 7%

6 M5 North 12% 4% 1% 18%

7 M5 South 14% 1% 5% 1% 21%

Total 82% 4% 11% 3%

23


July 2016

à The scheme generates an overall negative benefit across movements within Taunton.This is because it would allow more traffic to access Taunton at peak times and thiswould have a negative impact on junctions within the town, particularly those which arelikely to already be operating at or above capacity in the future years.

à The scheme generates a high level of benefit for movements into Taunton from theA303/A358 corridors. This is expected given that the scheme (as modelled) significantlyreduces delay on the A358 westbound approach. This approach operates over-capacityin the present day and would become worse by the future year without intervention.

à The scheme generates negative benefit for movements into Taunton from the M5. Thisdoes not appear to be an intuitive result at first given that the scheme improves capacityand reduces delay at Junction 25 for these movements, but more detailed analysis showsthat it is actually caused by increasing delays on the Toneway corridor (particularly atCreech Castle) which struggles to accommodate the higher traffic flows released by thescheme.

à The scheme generates negative benefit for movements from Taunton to Bridgwater andagain, this is likely to be due to higher delays at Creech Castle with the scheme in place.

à The scheme generates a high level of benefit for outbound movements from Taunton,and in particular towards the A303/A358 corridors.

à The scheme generates a high level of benefit for strategic level movements outside ofTaunton, such as between the A303/A358 corridor and the M5 northbound. This isexpected from an improvement of a strategic junction.

SCHEME BENEFITS (ALTERNATIVE GROWTH SCENARIOS)5.2

5.2.1 Table 5-8 shows the range of economic benefits that are predicted for each of the growthscenarios that have been modelled. Intuitively, higher levels of traffic in the network increasescheme benefits whilst lower levels of traffic lead to a reduction. This is an expected outcomebecause the level of traffic in the network (and particularly at Junction 25) will influence theamount of delay in the Do Minimum scenario and will therefore affect the amount of journey timesavings due to the scheme.

5.2.2 The low growth forecast has approximately 5% less traffic in the future year 2018 and 10% less inthe future year 2033. This reduction in traffic leads to a reduction in scheme benefits of around40%.

5.2.3 The high growth forecast (which includes the SES traffic) has approximately 5% more trafficduring the peak hours and this leads to an increase in scheme benefit of around 30%. It is of notethat the employment site is only included for the future year of 2033 onwards compared to the lowgrowth scenario which affects the entire appraisal period.

Table 5-8 Transport Benefits by Growth Scenario (£000, discounted to 2010, in 2010 prices)GROWTHSCENARIO

TRAVEL TIME VOC FUEL VOC NON-FUEL INDIRECT TAX TOTAL

Low 98,224 -5,994 -1,219 5,364 96,375(-39%)

Core 159,153 -7,571 -1,705 8,018 157,895

High 205,792 -6,961 -251 9,707 208,287(+32%)

24


July 2016

SCHEME BENEFITS (WITH A358 IMPROVEMENT SCHEME)5.3

WITHOUT SLIP ROADS TO M5

5.3.1 The results of this sensitivity test indicate that the Junction 25 scheme would generate a similarlevel of economic benefit with or without the A358 scheme in place (Table 5-9). The inclusion ofthe A358 scheme leads to an increase in flow on the A358 corridor therefore it might be expectedto lead to higher economic benefit due to the Junction 25 scheme.

Table 5-9 Transport Benefits – A358 Sensitivity Test (£000, discounted to 2010, in 2010 prices)

SCENARIO TRAVEL TIME VOC FUEL VOC NON-FUEL INDIRECT TAX TOTAL

Core 159,153 -7,571 -1,705 8,018 157,895

A358 dualling 156,936 -8,646 -2,952 9,336 154,674(-2%)

5.3.2 Further analysis of the economic appraisal results shows that, whilst the benefits arising in theinter peak period are higher with the A358 scheme in place, the benefits in the AM and PM peakperiods are lower, leading to a insignificant net change in overall benefit.

5.3.3 Analysis of the model indicates the following as the main reasons why there is less economicbenefit in the AM and PM peak periods when the A358 expressway scheme is in place:

à Pressure on A358/A378 Langport Road signals – the traffic flow on the A358 corridor ispredicted to increase significantly due to the A358 scheme, in addition to further gainsthat occur as a result of the Junction 25 scheme. With both schemes in place, thisjunction becomes over capacity in both peak hours, whereas it remains under-capacity inthe core scenario where only the Junction 25 scheme is considered. This would appearto be a sensible outcome however it has been assumed that this junction remainsunchanged as part of the A358 scheme (as it is already on a dualled section of thecorridor) but in reality it may be upgraded to accommodate higher traffic flows andtherefore may not become over-capacity in the future years. Further informationregarding the A358 scheme would be needed to better understand this and therefore itshould be possible to look at this in more detail in future stages of appraisal.

à Creech Castle – increases in traffic on the Toneway corridor predictably have an impactupon the overall level of vehicle delay at this junction. The Junction 25 scheme leads toan increase in flow on Toneway corridor and, as no intervention has been assumed in anyof the scenarios modelled, this junction is a source of negative benefit across all of thescenarios considered. However, with the A358 scheme in place there is a larger increasein traffic on Toneway and consequently this junction experience a higher level of overallvehicle delay, particularly during the AM peak period. This would appear to be a sensibleoutcome but it is noted that there are proposals for improvements at this junction as partof the sister ‘Toneway Corridor’ scheme which, if implemented, would be expected toreduce delays here and therefore reduce the negative impact of the Junction 25 schemewith or without the A358 scheme in place.

à Strategic Employment Site roundabout – despite being a new junction that is proposed aspart of the Junction 25 scheme, the model indicates that it becomes over-capacity oncethe bypass of Henlade village is connected as the eastern approach. This indicates that,if the A358 scheme does make a connection at this roundabout in the future, it would benecessary to ensure that the design provides adequate capacity for this. This issue islikely to be magnified with the inclusion of traffic to and from the employment site,however it is noted that a scenario including both the employment site and A358 schemehas not modelled at this time and would need to form part of future stages of appraisal.

25


July 2016

5.3.4 Given that the proposals for the A358 scheme are not well defined at this stage, there remainssignificant uncertainty surrounding this scheme which has not been fully addressed by thissentitivity test, despite it being the approach agreed with the ITA for the LTB. The mainassumptions and limitations are as follows:

à Wider reassignment of A303 traffic has not been modelled (as discussed in paragraph2.4.5) and therefore it might be expected that scheme benefits should be higher with theA358 scheme in place.

à The results are based on an assumed alignment for the A358 scheme which includes anew dual carriageway bypass of Henlade connecting into Junction 25 via the new linksforming part of the Junction 25 scheme.

à The results assume that a scheme similar to Junction 25 (e.g. providing a new signalisedarm) would not be delivered as part of the A358 scheme if the Junction 25 scheme wasnot implemented. If that were the case, it would not be reasonable to attribute as mucheconomic benefit to the Junction 25 scheme.

WITH SLIP ROADS TO M5

5.3.5 Introducing south facing slip roads as part of the A358 scheme would enable free flow movementbetween the A358 and M5 and would remove traffic making these movements from Junction 25.Analysis of the model shows that, in the scheme design year 2033, the slip roads would removearound 10% of traffic from the junction at peak times (not including any increases due to widerreassignment that may result from the dualling).

5.3.6 The results of this sensitivity test confirm that scheme benefits are significantly lower with the sliproads in place, but they also indicate that the scheme is still viable with this reduced level of trafficand suggest that there would still be a need for a scheme.

5.3.7 As referred to in paragraph 2.1.15, in order to avoid overestimating benefits with the slip roads inplace, benefits from 2025 – 2033 have been removed from the economic assessment due to theuncertainty over when the A358 scheme would be implemented. Potentially therefore, the drop inscheme benefits shown in this test are pessimistic and demonstrate a worst case.

Table 5-10 Transport Benefits – Sensitivity Test (£000, discounted to 2010, in 2010 prices)

SCENARIO TRAVEL TIME VOC FUELVOC NON-

FUELINDIRECT TAX TOTAL

Core 159,153 -7,571 -1,705 8,018 157,895

A358 dualling 156,936 -8,646 -2,952 9,336 154,674(-2%)

A358 dualling with free-flow slips 48,352 -2,318 264 3,140 49,438(-69%)

26


July 2016

ACCIDENT ASSESSMENT RESULTS5.4

5.4.1 The accident assessment indicates that there would be a reduction in the cost of accidents due tothe scheme, equating to a benefit of £3.1 million over the appraisal period (discounted to 2010 in2010 prices). The accident assessment results are described in more detail in the Social ImpactAppraisal Report12

5.4.2 Separate estimates of the reduction in the cost of accidents have not been calculated for thesensitivity test scenarios but to enable comparison of BCRs with the Core scenario, the samelevel of benefit due to accident savings has been included in the overall level of economic benefitreported in the Transport Economic Efficiency (TEE), AMCB and Public Accounts (PA) tables forthese scenarios (Appendix E).

MONETISED ENVIRONMENTAL ASSESSMENT RESULTS5.5

GREENHOUSE GASES

5.5.1 The TUBA results indicate that the scheme would cause an increase in the level of greenhousegas emissions and would therefore generate a negative economic benefit of £3.7 million over theappraisal period (discounted to 2010 in 2010 prices).

AIR QUALITY

5.5.2 No other impacts to air quality have been monetised for this assessment, as outlined in the ASR.

NOISE

5.5.3 The noise appraisal indicates that the scheme would generate a slight adverse noise impact andthat the ‘net present value of change in noise’ is calculated to be -£0.49 million. The results of thenoise appraisal are described in more detail in the Environmental Appraisal Summary Report13.

OTHER MONETISED IMPACTS5.6

CONSTRUCTION AND MAINTENANCE IMPACTS

5.6.1 The economic impact due to construction or on-going maintenance of the scheme has not beenassessed, as outlined in the ASR.

WIDER IMPACTS

5.6.2 The assessment of wider impacts indicates that the scheme would have a minor impact tobusinesses (Table 5-11).

Table 5-11 Economic benefits arising from wider impacts (£000, discounted to 2010, in 2010 prices)ELEMENT ECONOMIC BENEFIT

Business User Benefits £77,497

Output change in imperfectly competitive markets £7,750

12M5 Junction 25 Social Impact Appraisal Report (April 2016).13 M5 Junction 25 Environmental Appraisal Summary Report (April 2016)

27


July 2016

SUMMARY OF ECONOMIC IMPACTS5.7

5.7.1 The TEE, PA and AMCB tables presented in this section follow the WebTAG methodology andrefer to the Core scenario only. For the purposes of the LTB, developer contributions are treatedas a cost rather than a negative benefit. This increases both the Present Value of Benefits andthe Present Value of Costs, such that the Net Present Value remains the same but the Benefit toCost ratio decreases. These results are presented in Table 5-15 and Table 5-16.

5.7.2 TEE, PA and AMCB tables for the sensitivity test scenarios are provided in Appendix E.

TRANSPORT ECONOMIC EFFICIENCY (TEE)

5.7.3 The TEE table provides a summary of the travel time and vehicle operating cost benefits. Thebenefits are summarised by trip purpose. The TEE table for the core growth scenario is shown inTable 5-12 overleaf.

PUBLIC ACCOUNTS (PA)

5.7.4 The Public Accounts table details the source of the scheme costs and have been summarised bylocal and central government. The PA table is shown in Table 5-13 overleaf.

ANALYSIS OF MONETISED COSTS AND BENEFITS (AMCB)

5.7.5 The benefits from each individual assessment have been totalled to create the Present ValueBenefits (PVB) of the scheme. They have been summarised in the AMCB table along with thePVC and the BCR. The AMCB table for the core growth scenario is shown in Table 5-14 overleaf.

5.7.6 The results show that the scheme provides significant benefits to transport users, resulting fromthe significant improvement in the performance of the junction provided by the scheme. The M5Junction 25 scheme produces a BCR above 12, which represents Very High Value for Money.

28


July 2016

Table 5-12 Economic Efficiency of the Transport System

Non-business: Commuting ALL MODES ROAD

User benefits TOTAL Private Cars and LGVs

Travel time 23,340 23,340

Vehicle operating costs -55 -55

User charges

During Construction & Maintenance

NET NON-BUSINESS BENEFITS: COMMUTING 23,285 (1a) 23,285

Non-business: Other ALL MODES ROAD



Vehicle operating costs -6,843 -6,843

User charges


NET NON-BUSINESS BENEFITS: OTHER 49,095 (1b) 49,095

Business

User benefitsGoodsVehicles

BusinessCars & LGVs

Travel time 79,876 39,477 40,399

Vehicle operating costs -2,379 -2,823 444

User charges 0

During Construction & Maintenance 0

Subtotal 77,497 (2) 36,654 40,843

Private sector provider impacts

Revenue 0

Operating costs 0

Investment costs 0

Grant/subsidy 0

Subtotal 0 (3)

Other business impacts

Developer contributions -2,493 (4) -2,493

NET BUSINESS IMPACT 75,004 (5) = (2) + (3) + (4)

TOTAL

Present Value of Transport Economic EfficiencyBenefits (TEE)

147,384 (6) = (1a) + (1b) + (5)

Notes: Benefits appear as positive numbers, while costs appear as negative numbers. All entries are discounted present values, in 2010 prices and values

29


July 2016

Table 5-13 Public Accounts

ALL MODES ROAD

Local Government Funding TOTAL INFRASTRUCTURE

Revenue 0 0

Operating Costs 0 0

Investment Costs 4,479 4,479

Developer and Other Contributions -2,493 -2,493

Grant/Subsidy Payments 0 0

NET IMPACT 1,986 (7) 1,986

Central Government Funding: Transport

Revenue 0 0

Operating costs 0 0


Developer and Other Contributions 0 0


NET IMPACT 10,744 (8) 10,744

Central Government Funding: Non-Transport

Indirect Tax Revenues -8,018 (9) -8,018

TOTALS

Broad Transport Budget 12,730 (10) = (7) + (8)

Wider Public Finances -8,018 (11) = (9)

Notes: Costs appear as positive numbers, while revenues and ‘Developer and Other Contributions' appear as negativenumbers.All entries are discounted present values in 2010 prices and values.

30


July 2016

Table 5-14 Analysis of Monetised Costs and BenefitsAnalysis of Monetised Costs and Benefits

Noise -493 (12)

Local Air Quality (13)

Greenhouse Gases -3,770 (14)

Journey Quality (15)

Physical Activity (16)

Accidents 3,102 (17)

Economic Efficiency: Consumer Users (Commuting) 23,285 (1a)

Economic Efficiency: Consumer Users (Other) 49,095 (1b)

Economic Efficiency: Business Users and Providers 75,004 (5)

Wider Public Finances (Indirect Taxation Revenues) 8,018- (11) - sign changed from PA table,as PA table represents costs, notbenefits

Present Value of Benefits (see notes) (PVB) 154,241 (PVB) = (12) + (13) + (14) + (15) +(16) + (17) + (1a) + (1b) + (5) - (11)

Broad Transport Budget 12,730 (10)

Present Value of Costs (see notes) (PVC) 12,730 (PVC) = (10)

OVERALL IMPACTS

Net Present Value (NPV) 141,511 NPV=PVB-PVC

Benefit to Cost Ratio (BCR) 12.1 BCR=PVB/PVC

Note: This table includes costs and benefits which are regularly or occasionally presented in monetised form in transportappraisals, together with some where monetisation is in prospect. There may also be other significant costs and benefits, some ofwhich cannot be presented in monetised form. Where this is the case, the analysis presented above does NOT provide a goodmeasure of value for money and should not be used as the sole basis for decisions.

31


July 2016

BENEFIT TO COST RATIOS5.8

5.8.1 Several alternative formulations of BCRs are possible, using the ITA and WebTAG Methods andincluding additional monetised benefits to produce the ‘adjusted’ BCR. These are summarised forthe Core Scenario in Table 5-15.

Table 5-15 Core Scenario BCRs

Additional Monetised Impactsfor Adjusted BCR Wider Impacts 7750

Initial BCR -TUBA/WebTAG

Methodology

Initial BCR - ITAMethodology

(Note A)

Adjusted BCR -WebTAG

Methodology(Note B)

Adjusted BCR -ITA

methodology(Notes A and B)

Present Value of Benefits (PVB) 154,241 156,734 161,991 164,484Present Value of Costs (PVC) 12,730 15,223 12,730 15,223Net Present Value (NPV) 141,511 141,511 149,261 149,261Benefit to Cost Ratio (BCR) 12.1 10.3 12.7 10.8

Note A The ITA methodology removes the developer contribution from benefits(increasing the PVB) and includes it as a cost (increasing the PVC). Thisreduces the BCR (assuming it starts off higher than 1.0).

Note B The adjusted BCR includes benefits from Wider Impacts.

5.8.2 A comparison of BCRs across all scenarios tested is shown in Table 5-16. The benefits shown inthis table are adjusted according to the ITA methodology. Only the main components of schemebenefits (i.e. those calculated by TUBA such as travel time and costs) have been revised, basedon the corresponding SATURN modelling. Other monetised contributions (from noise, accidentsavings and wider impacts) are assumed to be the same as those in the Core scenario. This is areasonable approach as these figures are small compared to the contributions from changes intravel time and costs.

Table 5-16 Comparison of BCRs across all scenarios

SCENARIOPRESENT VALUE OF

BENEFITS (PVB)IN £000’S

PRESENT VALUE OFCOSTS (PVC)

IN £000’S

ADJUSTED BCR - ITAMETHODOLOGY

Core 164,484

15,223

10.8

A358 159,825 10.5

A358 with free flow slips 55,190 3.6

High growth (Core+SES) 216,947 14.3

Low growth 101,168 6.6

5.8.3 The BCR for the core scenario is 10.8 and therefore the scheme represents ‘Very High’ Value forMoney. This is based on the core forecasts and represents the best prediction of the impact ofthe scheme.

5.8.4 The BCRs for the different growth scenarios tests range from 6.6 to 14.3 and confirm that, whilstthe scheme benefits are sensitive to uncertainty in the traffic growth assumptions, the scheme stillgenerates a high BCR even with the lowest level of traffic growth assumed and would remain‘Very High’ Value for Money.

32


July 2016

5.8.5 The lowest BCR predicted is 3.6 and is associated with the scenario where new slip roads areimplemented between the A358 and M5 as part of the Highways England A358 scheme. Thisscenario is considered to be unlikely given the cost and practical constraints of constructing theslip roads however the scheme still generates a strong level of economic benefit which represents‘High’ Value for Money.

33


July 2016

6 CONCLUSIONS6.1.1 This report has outlined the methodology and results of an economic appraisal of the M5 Junction

25 scheme. This appraisal has been undertaken to support a Major Scheme Business Casewhich will be considered by the Heart of the South West Local Transport Board.

6.1.2 The economic appraisal is based on the future year traffic forecasts that have been prepared forscheme opening and design years. The development of the traffic model and the forecastingapproach that was adopted are described in detail in separate validation and forecasting reportswhich are also appended to the business case and should be read in conjunction with thiseconomic appraisal report. It has been concluded in these reports that the traffic model (andassociated forecasts) are suitable for use in an economic appraisal of the scheme.

6.1.3 Scheme costs for use in the appraisal have been provided by Somerset County Council andinclude allowance for risk and optimism bias appropriate to this stage of scheme assessment.Including these allowances, the total scheme cost is estimated to be £18.7 million (excluding land,landscaping and supervision).

6.1.4 Several different scenarios have been appraised due to various uncertainties surrounding thescheme. The core scenario provides the central growth forecast and is the best availableprediction based on the most up to date knowledge of future development sites and highwayschemes which are likely to affect demand and supply. The economic appraisal of the corescenario indicates that the scheme would generate a very high level of economic benefit, mostlythrough travel time savings arising from the additional capacity (and associated reduction indelays) provided by the scheme. The Benefit to Cost Ratio for the core scenario (using the ITA’spreferred methodology) is 10.8 and the scheme is therefore expected to represent ‘Very High’value for money.

6.1.5 An economic appraisal has also been undertaken for higher and lower growth scenarios in orderto understand the sensitivity of scheme benefits to uncertainty in the assumptions surroundingfuture traffic growth. Whilst the low growth scenario is a typical WebTAG forecast which includesa reduction across the whole modelled area, the high growth scenario has been used as anopportunity to test additional traffic associated with a proposed Strategic Employment Site whichwould be located directly adjacent to Junction 25 and may generate a significant amount ofadditional traffic at the junction. The economic appraisal of these alternative growth scenariosindicates a BCR range of 6.6 to 14.3. Whilst this suggests that the scheme benefits are sensitiveto uncertainty in the traffic growth assumptions (as would be expected), the scheme remains‘Very High’ Value for Money across the range.

6.1.6 A further scenario that has been tested includes an upgrade of the A358 corridor between theA303 and M5 which is currently proposed by Highways England as part of the Road InvestmentStrategy. As this scheme is in a very early stage of development it has been necessary to makea number of assumptions in relation to potential realignment of this route and options forconnection to the M5. The appraisal results show that, assuming all of the A358 traffic wouldcontinue to use Junction 25 to access the motorway, the A358 proposals would not have asignificant impact to the economic benefit of the Junction 25 scheme. However, if free flowaccess were to be provided between the upgraded A358 corridor and the M5 south of Junction25, it is likely that the economic benefit of the Junction 25 scheme would be reduced, albeitremaining in a ‘High’ value for money category.

Appendix ASCHEME PLANS

APPENDIX A-1

M5 JUNCTION 25 FEASIBILITY DESIGN

dysonn

Text Box

Appendix A-1 Intended to show improvements to Junction 25 only. It is understood that the Blackbrook Park arm will not be signalised despite being shown as signalised in this drawing. All of the works east of the junction are superseded by Appendix A-2.

APPENDIX A-2

M5 JUNCTION 25 INITIAL DESIGN PHASE 1 ANDPHASE 2

dysonn

Text Box

Appendix A-2 Intended to show works to the east of Junction 25 only. This drawing does not show the proposed works at Junction 25, these is more clearly shown in Appendix A-1.

Appendix BMODELLED NETWORKS

APPENDIX B-1

WIDER NETWORK

Contains OS data © Crown copyright and database right 2016

Appendix B-1 - Wider Network

APPENDIX B-2

TAUNTON NETWORK

Appendix CM5 JUNCTION 25 IMPROVEMENTS – FEASIBILITY COSTS (APRIL2016)

Feasibility Costs18th April 2016

M5 Junction 25 Improvements

M5 Junction 25 Improvements 16th March 2016

Feasibility Costs

Prepared by : W.Bailey

Name Will BaileyPosition Senior Quantity Surveyor

Checked by : N.Freeman

Name Neil FreemanPosition Associate

Approved by: M.Claridge

Name Mark ClaridgePosition Director

Rev No Comments Checked by Approved by Date1 NF MC 22/03/20162 NF MC 18/04/2016

AECOMBelvedere House, Pynes Hill, Exeter, Devon, EX2 5WSTelephone: 01392 663200

This document has been prepared by AECOM for the sole use of our client and in accordance with generally acceptedconsultancy principles, the budget for fees and the terms of reference agreed between AECOM and the Client. Any informationprovided by third parties and referred to herein has not been checked or verified by AECOM, unless otherwise expressly stated inthe document. No third party may rely upon this document without the prior and express written agreement of AECOM.

M5 Junction 25 ImprovementsSummary

Total costImprovementsPreliminaries 1,575,600Construction 7,878,000Main Contractors OH&P 567,216

10,020,816Professional fees, LA charges, surveys and site investigation. 801,665Project contingency 1,082,248Client direct costsClient supply items

11,904,729

11,904,729

Basis:

Assumptions:

Exclusions:

Value Added Tax (VAT)External ServicesAbnormal ground conditions over and above allowance madeOut of hours workingCosts in connection with soil contaminationCosts in connection with asbestosWork to existing roads carpark or highways or other work beyond the allowances statedCosts in respect to adjoining owners (party walls, oversailing rights, projection licences, etc)Land Purchase or transfer costs

Inflation Forecast

Currently no allowance for inflation has been included.

This Cost Plan has been prepared based on historic benchmarking data. A number of assumptionshave been made which will require budget confirmation as further information is provided.

The Cost Plan has been priced at second quarter 2016 base date. The basis of pricing assumescompetitively tendered procurement route.

The costs have been based on the existing drawing and Highlighted drawing MJ004045-SK-004 anddiscussions with SCC. Due to the limited design information the costs are based purely onassumptions. No further design information is yet available and as such allowances have beenbased on similar schemes and adjusted for known abnormals. Aecom have held discussions withthe Councils Engineer and Commissioning Manager in order to ensure the works are fully costed.

The following items are excluded from the Cost Plan. The list is intended as a guide only and cannotbe relied upon to be exhaustive:

TOTAL BUILDING COSTS

SUB- TOTAL

TOTAL PROJECT COSTS

M5 Junction 25 Improvements

Cost Elements

Quantity Unit Rate Total CommentsElement of Works

Additional lane to existing junction 1,400.00 m2 300.00 420,000 To accommodate 4th lane

Structural alteration to support above 1.00 item 500,000.00 500,000Additional support and extended area will requirenew structure.

Embankment stabilisation and retaining walls to M5 200.00 m2 650.00 130,000 Assumed retaining walls/ground anchors

New cycle way under current structure 1.00 item 250,000.00 250,000 Attached to and modification of existing structureAlteration of existing junction lanes 1.00 item 150,000.00 150,000 To elongate current roundabout

Raised Embankment for new road 300 m 2,250 675,000Allowance for elevated road due to flood plain andlevel change.

Additional Cut/Fill and allowance 8,400 m3 50 420,000 Estimated structural fill allowanceDrainage Attenuation 1 item 250,000 250,000 Assumed additional attenuation required.Culvert for river/brook crossing 1 item 250,000 250,000 Culvert for existing brook under road

New Dual Carriageway 11,242 m2 250 2,810,500

To include all associated works (lighting, kerbs,drainage etc. Includes surface and general worksfor raised section and all new dual carriage way.

New Roundabout 1 item 500,000 500,000 To include junctions to future development.New single lane stub junction off new roundabout 1 item 75,000 75,000 To support future development schemeNew double lane stub off new roundabout 1 item 125,000 125,000 To support future A358 HE schemeNew Junction off A road 1 item 175,000 175,000 Elevated rate to account for level change.New traffic island/crossing between green & blue marked roads 1 item 55,000 55,000 Assumed new bridges not required.New small traffic island to junction to accommodate bus lane 1 item 35,000 35,000

Modification to existing junctions 4 nr 35,000 140,000Assumed further modification to existing requiredto accommodate traffic flow.

New traffic signal sets 8 nr 75,000 600,000Assumed nr to include associatedworks/connections and markings.

1 item 220,000 220,000

Assumed retaining structures will be required dueto change in levels and made ground (currentnoise attenuation bund)

Resurfacing of existing 1,500 m2 65 97,500Assumed an area of existing will require re-surfacing due to tying in of new works.

7,878,000

Preliminaries 20% 1,575,600 Elevated to include significant traffic managementMain Contractors OH&P 6% 567,216

2,142,816Professional fees, LA charges, surveys and site investigation. 8% 801,665 Assumed figureProject contingency 10% 1,082,248Client direct costs 0Client supply items 0

1,883,913

11,904,729

Retaining structures/ stabilisation to made ground due to level change topark and ride area

TOTAL PROJECT COSTS

SUB- TOTAL

TOTAL BUILDING COSTS

SUB- TOTAL

Appendix DTEE, PA AND AMCB TABLES FOR SENSITIVITY TESTS

APPENDIX D-1

LOW GROWTH SCENARIO

LOW GROWTH SCENARIOEconomic Efficiency of the Transport System




Vehicle operating costs -21 -21

User charges







User charges



Business


BusinessCars & LGVs

Travel time 49,661 22,953 26,708


User charges 0


Subtotal 47,156 (2) 20,378 26,778


Revenue 0

Operating costs 0

Investment costs 0

Grant/subsidy 0

Subtotal 0 (3)




TOTAL


88,519 (6) = (1a) + (1b) + (5)


LOW GROWTH SCENARIOPublic Accounts

ALL MODES ROAD


Revenue 0 0

Operating Costs 0 0




NET IMPACT 1,986 (7) 1,986


Revenue 0 0

Operating costs 0 0




NET IMPACT 10,744 (8) 10,744



TOTALS




LOW GROWTH SCENARIOAnalysis of Monetised Costs and Benefits

Analysis of Monetised Costs and Benefits

Noise -493 (12)













OVERALL IMPACTS




APPENDIX D-2

HIGH GROWTH SCENARIO (CORE + SES)

HIGH GROWTH SCENARIOEconomic Efficiency of the Transport System




Vehicle operating costs 121 121

User charges







User charges



Business


BusinessCars & LGVs

Travel time 108,140 59,890 48,250


User charges 0


Subtotal 106,664 (2) 57,582 49,082


Revenue 0

Operating costs 0

Investment costs 0

Grant/subsidy 0

Subtotal 0 (3)




TOTAL


196,090 (6) = (1a) + (1b) + (5)


HIGH GROWTH SCENARIOPublic Accounts

ALL MODES ROAD


Revenue 0 0

Operating Costs 0 0




NET IMPACT 1,986 (7) 1,986


Revenue 0 0

Operating costs 0 0




NET IMPACT 10,744 (8) 10,744

0

Central Government Funding: Non-Transport0 Indirect Tax Revenues -9,707 (9) -9,707

TOTALS




HIGH GROWTH SCENARIOAnalysis of Monetised Costs and Benefits


Noise -493 (12)













OVERALL IMPACTS




APPENDIX D-3

A358 SCENARIO

A358 SCENARIOEconomic Efficiency of the Transport System




Vehicle operating costs 347 347

User charges







User charges



Business


BusinessCars & LGVs

Travel time 72,825 35,579 37,246

Vehicle operating costs -3,332 -3,291 -41

User charges 0


Subtotal 69,493 (2) 32,288 37,205


Revenue 0

Operating costs 0

Investment costs 0

Grant/subsidy 0

Subtotal 0 (3)



NET BUSINESS IMPACT (5) = (2) + (3) + (4)

TOTAL


142,848 (6) = (1a) + (1b) + (5)


A358 SCENARIOPublic Accounts

ALL MODES ROAD


Revenue 0 0

Operating Costs 0 0




NET IMPACT 1,986 (7) 1,986


Revenue 0 0

Operating costs 0 0




NET IMPACT 10,744 (8) 10,744

Central Government Funding: Non-Transport0 Indirect Tax Revenues -9,336 (9) -9,336

TOTALS




A358 SCENARIOAnalysis of Monetised Costs and Benefits


Noise -493 (12)













OVERALL IMPACTS




APPENDIX D-4

A358 INCLUDING SLIP ROADS SCENARIO

A358 INCLUDING SLIP ROADS SCENARIOEconomic Efficiency of the Transport System




Vehicle operating costs 1,165 1,165

User charges







User charges



Business


BusinessCars & LGVs

Travel time 23,657 5,173 18,484


User charges 0


Subtotal 22,586 (2) 3,493 19,093


Revenue 0

Operating costs 0

Investment costs 0

Grant/subsidy 0

Subtotal 0 (3)

Other business impacts Developer contributions -2,493 (4) -2,493


TOTAL


45,944 (6) = (1a) + (1b) + (5)


A358 INCLUDING SLIP ROADS SCENARIOPublic Accounts

ALL MODES ROAD


Revenue 0 0

Operating Costs 0 0




NET IMPACT 1,986 (7) 1,986


Revenue 0 0

Operating costs 0 0




NET IMPACT 10,744 (8) 10,744



TOTALS




A358 INCLUDING SLIP ROADS SCENARIOAnalysis of Monetised Costs and Benefits


Noise -493 (12)













OVERALL IMPACTS




ECONOMIC ASSESSMENT REPORT - Somerset

Documents

Transcript of ECONOMIC ASSESSMENT REPORT - Somerset