Torbay Council
Prepared by
Parsons Brinckerhoff
The Forum
Barnfield Road
Exeter
EX1 1QR
Prepared for
Torbay Council
Roebuck House
Abbey Road
Torquay
TQ2 5TF
September 2009
Report Number HPE98091A/1/1
DRAFT
AUTHORISATION SHEET
Client: / Torbay CouncilProject: / Tweenaway Cross Business Case
Address: / Roebuck House, Abbey Road, Torquay, TQ2 5TF
PREPARED BY
Name: / Katherine Moody / Tom Eaton
Position: / Senior Transportation Planner / Engineer
Date: / September 2009
AGREED BY
Name: / Ian Beavis / Andy Davison
Position: / Regional Associate / Regional Associate
Date: / September 2009
AUTHORISED FOR ISSUE
Name: / Ian Beavis / Andy Davison
Position: / Regional Associate / Regional Associate
Date: / September 2009
DISTRIBUTION
Copy no. / Company
1 / Andy Young, Torbay Council
2 / Patrick Carney, Torbay Council
3 / PB Office Copy (Exeter)
CONTENTS
Page
1Introduction
2Value for money
2.1Overview
2.2Modelled Period
2.3Modelling Methodology
2.4Scheme Costs
2.5Scheme Results
3Financial / Commercial
3.1Programme
3.2Cost Estimate
3.3Spend Profile
3.4Cost Control
4Conclusion
September 2009
Tweenaway Cross Business Case1Introduction
1.1.1This report provides a summary of the Value for Money and the Financial / Commercial sections required as part of the submission to the Regional Transport Body secretariat.
2Value for money
2.1Overview
2.1.1In order to assess the value for money for the Tweenaway Cross scheme and calculate the BCR, a spreadsheet approach has been undertaken that uses a combination of software packages: LINSIG (for estimating vehicle delays at the existing and scheme layouts), Junction User Interface Cost Evaluation (JUICE) (for calculating the economic benefits based upon traffic flows and the LINSIG) and COBA to derive the investment cost values.
2.1.2This section provides a summary of the approach used to calculate the BCR that has been quoted in the Expression of Interest document.
2.1.3Only the Tweenaway Cross junction has been assessed. Link improvements to downstream junctions have not been considered and it is likely these will produce extra benefits.
2.2Modelled Period
2.2.1A 15-year period from 2011-2026 has been assessed. The models have assessed the AM peak and PM peak weekday hours.
2.3Modelling Methodology
2.3.1A Do Minimum scenario (without the scheme) and Do Something scenario (with the scheme) have been produced. The Do Minimum scenario has assumed the existing situation at the junction.
Travel Time Benefits
2.3.2The travel time costs for the Do Minimum and the Do Something scenarios have been calculated allowing the travel time saving with the scheme in place to be determined. The travel time cost has been calculated for the AM and PM peak hours for the Do Minimum and Do Something scenario and discounted to 2002 prices.
2.3.3The travel time costs calculated for each arm of the junction were calculated for each year and each vehicle type (cars, Light Goods Vehicles, Other Goods Vehicles 1 and 2, and Public Service Vehicles) and purpose in terms of work and non-work trips for the AM and PM peak hours.
2.3.4In order to calculate the travel time costs, the traffic inflow in the year was identified. This was based on the observed number of vehicles (by vehicle type) on each arm of the junction in 2003. In order to calculate the future year traffic inflow, values relating to growth in traffic by vehicle type from the COBA manual were assumed.
2.3.5In addition to the traffic inflow, it is necessary to identify the delay at the junction. This has been determined using the LINSIG software. The delay in the future years has been identified and input into the JUICE software for each of the future years.
2.3.6The travel time cost for each arm of the junction has been calculated based on the value of time from COBA for working and non-working time and the growth in the value of time has been considered.
2.3.7The travel time cost for each arm of the junction has been combined to give a travel time cost per hour for the junction. This has been converted to the costs per year based on the flow group structure and the number of AM and PM Peak hours in the year depending on which time period is being assessed.
2.3.8The total travel time costs per year have been discounted to 2002 prices using a discount factor of 3.5% as detailed in WebTAG 3.5.4.
2.3.9The travel time savings have subsequently been identified based on the difference in the travel time costs for the Do Something and Do Minimum scheme options. The results are indicated in Table 2.1.
Table 2.1: Travel Time costs for the Do Minimum and Do Something Scenarios and the calculated Travel Time Savings
Travel time costs / Do Minimum / Do Something / Travel Time SavingsAM Peak (0800-0900) / £11,272,000 / £3,138,000 / £8,134,000
PM Peak (1700-1800) / £9,002,000 / £3,239,000 / £5,763,000
Total Travel Time Costs / £20,274,000 / £6,377,000 / £13,897,000
Accident benefits
2.3.10Accident benefits have not been analysed - COBA would not return any accident benefits at the Tweenaway Cross junction, as the COBA junction type is the same for the existing layout and the scheme layout. A desktop study of accident data would be required to assess on a case-by-case basis which accidents might be saved by the scheme.
Vehicle Operating Costs
2.3.11Vehicle operating costs (VOCs) have not been analysed - it is assumed that since the scheme layout does not alter travel distances in any significant way, that VOCs will remain the same.This does however result in a conservative estimate of the benefits as Vehicle Operating Costs are also influenced by speed.VOCs are higher at lower speeds and in congestion and therefore any improvements in speed as a result of the scheme could result in further benefits.
2.4Scheme Costs
2.4.1The scheme cost is based on COBA investment cost values. The present value of costs discounted to 2002 values is £4,637,000.
2.5Scheme Results
2.5.1The results for the proposed scheme are illustrated in Table 2.2 below.
Table 2.2: Scheme Results
Present Value of Benefits (PVB) / Present Value of Costs (PVC) / Benefit Cost Ratio (BCR)£13,897,000 / £4,637,000 / 2.997
All values are discounted to 2002 values except BCR value
2.5.2The economic assessment shows positive travel time benefits for the proposed scheme. Travel time benefits arise as the scheme provides a reduction in the delay to vehicles. The results show that the benefit/cost ratio (BCR) is positive indicating that the scheme produces greater benefits than the cost of implementing the scheme.
2.5.3The BCR is a conservative estimate due to the fact that the assessment has been carried out over a 15 year period and only for the AM and PM peak weekday hours.The scheme is likely to result in benefits over a much greater proportion of the week and on weekends and bank holidays. Further benefits mayalso result from an assessment of the accidents and Vehicle Operating Costs.
3Financial / Commercial
3.1Programme
3.1.1Below is the outline programme for construction of the scheme:
Land NegotiationsJune 2009
Torbay Advanced WorksSeptember 2009
Appoint ContractorDecember 2009
Start Construction of Interim Scheme (Phase 1)January 2010
Finish Construction of Interim Scheme (Phase 1)May 2010
Start Construction of Interim Scheme (Phase 2)September 2010
Finish Construction of Interim Scheme (Phase 2)March 2011
Start Construction of Final Scheme (Phase 3)September 2011
Finish Construction of Final Scheme (Phase 3)May 2012
Maintenance CompleteMay 2013
3.2Cost Estimate
3.2.1The complete scheme cost estimate is £5,498,871. The breakdown of the cost estimate is included in Table 3.1 below.
Table 3.1: Breakdown of cost estimates
Interim Scheme(Phase 1 & 2) / Final Scheme
(Phase 3) / TOTAL
Works (incl signals) / £ 2,113,602 / £ 1,312,394 / £ 3,425,996
Statutory Undertakers Diversions / £ 682,316 / £ 541,801 / £ 1,224,117
Land and Pt 1 Claims / £ 50,000 / £ 450,000 / £ 500,000
Design, Preparation and supervision (7.5%) / £ 209,694 / £ 139,065 / £ 348,758
TOTAL / £ 3,055,612 / £ 2,443,259 / £ 5,498,871
3.2.2The works cost estimate is based on the original cost estimate undertaken in 2005 from the outline design BoQ. The 2005 cost has been split into the 2 proposed schemes, the Interim Scheme and Final Scheme. The Cost estimate has been updated from 2005 to Quarter 1 2009 using the Road Construction Tender Price Index (RCTPI). Optimism bias and future inflation have been excluded.
3.2.3A contingency of 22% has been included within these costs.
3.2.4Updated Statutory Undertakers estimates have been included where available; however costs for all proposed works have not yet been confirmed.
3.2.5The cost estimate will be updated during the detailed design process as more information becomes available.
3.3Spend Profile
3.3.1Figure 3.1 illustratesthe projected profile spend for the construction of both the interim and final scheme.
Figure 3.1: Spend Profile
3.4Cost Control
3.4.1A joint owned Project Risk Register will be maintained throughout the scheme detailing risks and possible impacts, as information is received about risk items the impact and probability can be more defined. The risk register will become part of the monthly progress meetings to flag up any cost implications that can be foreseen, as well as possible mitigation measures.
4Conclusion
4.1.1This report has provided a summary of the Value for Money and the Financial / Commercial sections required as part of the submission to the Regional Transport Body secretariat. This information should be added to the larger document that is being produced by Torbay Council for submission to the Regional Transport Body secretariat.
4.1.2This report utilises the information available in the Expression of Interest Form in the Value for Money section and considers the most recent cost estimates associated with the updated scheme in the Financial / Commercial section, utilising the most up-to-date information at the current time.
September 2009Page1