ACCURACY OF TRAFFIC FORECASTS AND COST ESTIMATES ON LARGE TRANSPORTATION PROJECTS

Little research has been carried out on before-and-after studies of traffic and construction costs in large transportation infrastructure projects. The few studies that do exist show that forecasts of construction costs tend to be underestimated and those of traffic, overestimated. An examination of construction costs and traffic in seven large Danish bridge and tunnel projects indicates that, on average, construction costs were underestimated and traffic was overestimated in the initial phases of planning. This pattern is also found for similar projects in other countries. When the results of all the projects are pooled, it is seen that cost overruns of 50 to 100% are common and that overruns above 100% are not uncommon. Traffic forecasts that are off by 20 to 60% when compared with actual development are frequent in large transportation infrastructure projects. The result of this overoptimism in the initial planning phases is that decisions are based on misleading forecasts that may lead to a misallocation of funds and underperforming projects.

• Record URL:
  https://doi.org/10.1177/0361198196151800112
• Record URL:
  https://scholar.google.com/scholar_lookup?title=ACCURACY+OF+TRAFFIC+FORECASTS+AND+COST+ESTIMATES+ON+LARGE+TRANSPORTATION+PROJECTS&author=M.+Skamris&author=B.+Flyvbjerg&publication_year=1996
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309062144
• Supplemental Notes:
  • This paper appears in Transportation Research Record No. 1518, Transportation Planning Applications.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Skamris, M K
  • Flyvbjerg, B
• Publication Date: 1996

Language

• English

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 65-69
• Serial:
  • Transportation Research Record
  • Issue Number: 1518
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Accuracy; Before and after studies; Bridges; Construction; Construction projects; Cost estimating; Cost overruns; Costs; Estimates; Infrastructure; Traffic estimation; Tunnels
• Uncontrolled Terms: Construction costs; Fund allocations
• Geographic Terms: Denmark
• Old TRIS Terms: Overruns; Traffic forecasts
• Subject Areas: Bridges and other structures; Construction; Finance; Highways; Planning and Forecasting; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 00725618
• Record Type: Publication
• ISBN: 0309062144
• Files: TRIS, TRB
• Created Date: Sep 19 1996 12:00AM