Differential movement at embankment-bridge structure interface in Illinois

Settlement of roadway pavement surfaces near highway bridge abutments often leads to abrupt grade differences at the abutments. These grade differences subject vehicles to a bump, which may lead to driver discomfort and potentially unsafe driving conditions. Furthermore, differential movement requires costly and repeated maintenance work that usually impedes the flow of traffic. The sources of differential movement in Illinois can be divided into six major categories: (a) compression or erosion of materials at the approach embankment-abutment interface, (b) a broken approach slab, (c) compression of foundation soils, (d) compression or internal erosion of embankment soils, (e) poor construction grade control, and (f) areal distortion of foundation soils. An approach gradient equal to or greater than 1/100 to 1/125 appears to cause rider discomfort and therefore is proposed as a criterion for initiating remedial measures.