Research Activities: 2002

Evaluation of Bridge Approach Slabs Performance and Design




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Sequential Number


Matching Research Agency

Missouri Department of Transportation

Principal Investigator

Ronaldo Luna, PhD, PE
Associate Professor
Department of Civil Engineering
University of Missouri-Rolla
130 Butler-Carlton Hall
Rolla, MO 65409

Student Involvement

Jon Robison and Andy Wilding

Project Objective

To identify and quantify the failure mechanisms recently observed at the bridge approach slabs on approach embankments. This study will result in conclusions and recommendations along with potential actions for implementation by MoDOT to avoid these failures in the future.

Project Abstract

During the 1990's MoDOT built more bridges than 47 other states, of these a significant percentage have experienced settlement of their approaches. In some cases these structural slabs have even cracked near the abutment or experienced excessive settlement at the sleeper slab producing a dip at that location. These deformations affect the riding comfort of passengers and when the deformation is too excessive or abrupt it may even be unsafe. The current design of these bridge approach slabs includes provisions for the pumping if these slabs as a remedial measure. Several districts have spent considerable maintenance resources to fix these slabs and often disrupting other programmed maintenance operations. What has made this problem so severe for the Department is the fact of these failures have occurred soon after the bridge is open to traffic or before paving. These deformation failures can be induced by different factors such as the configuration at the bridge abutment, embankment soils, foundation soils, construction methods, etc. However, only one design is available for all the possible combinations. The classification of the most common combinations of these conditions and identifying the construction sequence and procedures (underdrain, staged construction, use of clay plugs, etc.), can result in design and construction recommendations to optimize performance. The findings will presented from the geotechnical point of view, however, any structural issues will be raised as appropriate.

Anticipated Benefits

This study will provide MoDOT with recommendations and guidance on how to improve bridge approach design and construction. Suggested design options will be presented including the construction sequence and procedures. A unique advantage of this research is the fact that the sleeper slab task force can serve as a sounding board on the implementation issues related to the study. The final report will include conclusions and recommendations of the typical embankment conditions and configurations to be used by designers and construction personnel. The report will also include options of how to implement the research findings.

Modal Orientation

Bridge approach slab assessment


Project Start Date:11/18/2002
Project End Date:09/30/2003

Relationship to other Research/Projects


Technology Transfer Activities


Transportation Research Board Keywords

Bridge approach Slabs, embankment fills, sleeper slab, deformation