IDEAS home Printed from
MyIDEAS: Log in (now much improved!) to save this article

Inaccuracy of traffic forecasts and cost estimates on large transport projects

Listed author(s):
  • Skamris, Mette K.
  • Flyvbjerg, Bent

Little research has been carried out on before-and-after studies of traffic and costs in large transport infrastructure projects. The few studies made all show a tendency for forecasts of construction costs to be underestimated, and for traffic forecasts to be overestimated. An examination of construction costs and traffic in seven large Danish bridge and tunnel projects shows that construction costs have been underestimated and traffic has been overestimated in the initial phases of planning. This pattern is also found in studies from other countries of large transport infrastructure projects. When the results of the Danish and the other projects are pooled together, the main lesson to be learnt is that cost overruns of 50-100% are common and overruns above 100% are not uncommon. Traffic forecasts that are incorrect by 20-60% compared with actual development are common in large transport infrastructure projects. The result of this overoptimism in the initial phases of planning is that decisions are based on misleading forecasts that may lead to a misallocation of funds and underperforming projects.

If you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.

File URL:
Download Restriction: Full text for ScienceDirect subscribers only

As the access to this document is restricted, you may want to look for a different version under "Related research" (further below) or search for a different version of it.

Article provided by Elsevier in its journal Transport Policy.

Volume (Year): 4 (1997)
Issue (Month): 3 (July)
Pages: 141-146

in new window

Handle: RePEc:eee:trapol:v:4:y:1997:i:3:p:141-146
Contact details of provider: Web page:

Order Information: Postal:

No references listed on IDEAS
You can help add them by filling out this form.

This item is not listed on Wikipedia, on a reading list or among the top items on IDEAS.

When requesting a correction, please mention this item's handle: RePEc:eee:trapol:v:4:y:1997:i:3:p:141-146. See general information about how to correct material in RePEc.

For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Dana Niculescu)

If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

If references are entirely missing, you can add them using this form.

If the full references list an item that is present in RePEc, but the system did not link to it, you can help with this form.

If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your profile, as there may be some citations waiting for confirmation.

Please note that corrections may take a couple of weeks to filter through the various RePEc services.

This information is provided to you by IDEAS at the Research Division of the Federal Reserve Bank of St. Louis using RePEc data.