Iowa LTAP has moved from CTRE to the Institute for Transportation

Identifying bridge approach problems, causes, and possible solutions

broken concrete embankment beneath bridge

Failure of concrete slope protection due to erosion.

Bridge approach settlement and the result-ing formation of "bumps" at the end of bridges is a common problem in Iowa. In addition to annoying motorists, these bumps result in considerable maintenance costs.

David J. White, assistant professor of civil, construction, and environmental engi-neering at ISU, recently led a project that investigated bridge approach problems and recommended improvements to bridge approach design, construction, and main-tenance. The project was sponsored by the Iowa Highway Research Board (TR-481). Following are highlights.

Causes of approach settlement

The project team determined that approach settlement can be caused by a number of factors:

Common bridge approach problems

White's team observed the following bridge approach problems at existing bridges with poor performance:

Recommended design alternatives

The following design alternatives show promise:

For more information

See the project report, Identification of the Best Practices for Design, Construction, and Repair of Bridge Approaches, and a technology transfer summary on the project web page.

If you have specific questions, contact David White, 515-294-1463,


Contact Iowa LTAP
2711 S. Loop Drive, Suite 4700
Ames, IA 50010
Phone: 515-294-8103
FAX: 515-294-0467