Bumps at Bridge Approaches: Two Case Studies for Bridges at El-Minia Governorate, Egypt

Abstract

A differential settlement at the end of a bridge near the interface between the abutment and the embankment is a persistent problem for highway agencies, commonly called “bumps at bridge approaches”. There are many undesirable effects of these uneven and irregular transitions such as: decrease in steering response, distraction to the driver, added risk and expense to maintenance operation, in addition to reduction in a transportation agency’s public image. A 2-D finite element model (FEM) was developed, using PLAXIS software package, and verified against results of six large scale laboratory experiments. The six experiments were conducted using a special well-established laboratory model at Texas A&M University, USA, called Bridge to Embankment Simulator of Transition (B.E.S.T.) device. The developed FEM was also used to investigate mobilized differential settlements at two bridge approaches within El-Minia Governorate, Egypt; the estimated mobilized bumps were also compared with available field observations. The results show good agreement between numerical model and field observations of mobilized bumps for the investigated two bridges. The presence of the transition slab reduces the differential settlement as it distributes settlements between each end of the transition slab. The developed FEM satisfactory estimated settlements at the end of the bridge. Mobilized bumps are less severe when there is a transition slab, appropriate fill material, and/or well compacted subgrade.