An Innovative Focus on Highway Bridge Approach Slabs

Quarterly Reports Other Documents Final Report
December 2009
March 2010
June 2010
September 2010
December 2010
June 2011
Research Brief Final Report

Primary Investigator

Mike Oliva
University of Wisconsin
1415 Engineering Drive
Madison, WI 53706


An approach slab is the portion of a roadway just prior to a highway bridge. Their construction is intended to minimize the elevation difference between the roadway and a bridge due to differential settlement of the roadway bed. It was estimated in 1997 that transportation departments in the US spend $100 million annually on maintenance problems in approach slabs and bridges due to the bump created by approach slab settlement (Ha, et al., 2002). The objectives of this project will be to develop rational design and improved construction methods to create much more durable approach slabs that will be able to resist the increasingly heavy freight truck loads for use in either new bridge construction or rapid approach slab replacement.


The proposed work is intended to develop design methods for highway bridge approach slabs as beam elements that allow rapid construction, improved durability, and have design procedures that are based on a rational understanding of the characteristics of the embankment backfill acting as a slab foundation system.


  1. Collect a database of current practices in highway
    approach slab design and construction as well as on backfill characteristics and methods for estimating time dependent settlement.
  2. Analytical methods will be employed to simulate the subgrade conditions and likely settlement under approach slabs.
  3. Improvements on existing methods of designing and constructing approach slabs, to meet span requirements related to expected settlement, will be developed and examined analytically.
  4. Suggested approach slab systems and rational design methods based on subgrade conditions and likely settlement will be developed.

Project Information

  • Duration: 12 months
  • Dates: October 1, 2009 – September 30, 2010
  • Budget: $79,998
  • Student Involvement: One graduate student
  • Modal Orientation: Highway
  • Project ID: CFIRE 03-10
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