Bridge Load Testing in Surrey

This paper describes the use of load testing to more accurately assess the load capacity of three bridges in Surrey. Two reinforced concrete bridges, one a subway roofspan and one an arch, had been assessed previously with the results of 3t and no live load, respectively. In common with many similar structures they showed few signs of distress in the main structural components, although they did require other maintenance. A third bridge, consisting of three identical cast iron spans, was already subject to a 7.5t weight restriction and had been assessed at 3t. In 1995, Surrey County Council appointed Peter Lindsell & Associates to carry out supplementary load tests on the three bridges. This paper describes the load testing methodology used. In all cases the measured strains under controlled live load, consisting of preweighed aggregate lorries, were considerably less than those predicted by the use of conventional analyses. The results of the load tests were used to modify the original assessment models, and considerably enhanced assessment live load capacities were obtained.

P. Lindsell and G. Cole