The nature and causes of the differential settlements between a bridge deck and the adjoining highway approach pavement have been the subject of an increasing number of investigations in recent years. This settlement of the highway approach pavement not only presents a hazardous condition to rapidly moving traffic, but creates a rough and uncomfortable ride. These defects of the pavement surface require costly maintenance and, where a heavy traffic flow exists, the maintenance operation may tend to impede the normal flow.

Bridge abutments in Kentucky are usually founded on relatively a stable foundation such as rock or point-bearing piles to rock, and practically speaking, cannot settle. Highway approach pavements, on the other hand, are located on an embankment and foundation which are potentially free to settle. The extent to which either settlement of the embankment or foundation contributes to the approach settlement will obviously depend on the particular conditions at any given bridge site. Data obtained from a survey of existing bridge approaches conducted in the summers of 1964 and 1968 have provided general information as to the prevalence of the problem in Kentucky. In addition, these data imply there is a general relationship between development of the approach fault and such possible causative factors as the type of abutment, geological conditions, and soils conditions. This report surrnnarizes the general relationship between the occurrence of bridge approach settlement and various conditions at the bridge sites.

Report Date


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No. 277

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The opinions, findings, and conclusions in this report are not necessarily those of the Department of Highways or the Bureau of Public Roads.