RISK ANALYSIS FOR PRIVATELY FUNDED TRANSPORT SCHEMES

Understanding the accuracy of traffic forecasts for privately financed transport schemes is important, particularly when the payment is by toll or shadow toll. Concession companies and their financial backers can be financially dependent on every vehicle. Hence, they need to know both the most likely outcome and the potential downside. There are numerous sources of uncertainty in traffic forecasts. Some relate to the existing situation, such as the accuracy of base counts. Some relate to forecasting issues, particularly the extent and distribution of economic growth. This paper describes a practical method of assessing the uncertainty in forecast traffic flows based on the uncertainty in the input parameters. Initially, the "most likely" values of all parameters are used to produce a model forecast. Then sensitivity functions are defined for each parameter. Sensitivity tests determine the changes in forecast flows arising from variations in each parameter. Then, a measure of the potential spread of each parameter is determined. For example, if the most likely growth in gdp is assessed as being 3% pa., how likely is it that only 2% pa will be achieved and how does this affect the traffic forecasts. All of the sensitivities are combined in a spreadsheet risk analysis model. Multiple random selections are made from the individual distributions generating a probability distribution about the overall traffic forecast. The spreadsheet outputs allow probabilities to be ascribed to different levels of forecast flow. This provides essential information to financial institutions in preparing concession bids for privately financed transport schemes. For the covering abstract see ITRD E105584.

• Record URL:
  http://abstracts.aetransport.org/conference/index/id/5
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0860503259
• Corporate Authors:

  PTRC Education and Research Services Limited

  Glenthorne House, Hammersmith Grove
  London W6OL9,   England 
• Authors:
  • BOYCE, A M
• Conference:
  • TRANSPORTATION PLANNING METHODS. PROCEEDINGS OF SEMINAR F, EUROPEAN TRANSPORT CONFERENCE, 27-29 SEPTEMBER 1999, CAMBRIDGE, UK.
• Publication Date: 1999-9

Language

• English

Media Info

• Features: References;
• Pagination: p. 237-50
• Serial:
  • Volume: P434

Subject/Index Terms

• TRT Terms: Conferences; Errors; Financing; Forecasting; Mathematical analysis; Mathematical models; Payment; Risk taking; Road construction; Sensitivity; Tenders; Tests; Toll collection; Toll roads; Traffic flow; Variables
• ITRD Terms: 6471: Analysis (math); 137: Bid; 8525: Conference; 6440: Error; 244: Financing; 132: Forecast; 6473: Mathematical model; 272: Payment; 2259: Risk taking; 3665: Road construction; 5928: Sensitivity; 137: Tender; 6255: Test; 291: Toll collection; 2702: Toll road; 671: Traffic flow; 9086: Variability
• Subject Areas: Construction; Data and Information Technology; Finance; Highways; Marine Transportation; Operations and Traffic Management;

Filing Info

• Accession Number: 00796500
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• ISBN: 0-86050-325-9
• Files: ITRD
• Created Date: Aug 2 2000 12:00AM