A CALCULATION MODEL FOR THE NOISE FROM STEEL RAILWAY BRIDGES

The sound level of a train crossing a steel railway bridge is usually about 10 dB higher than on plain track. In the Netherlands there are many such bridges which, for practical reasons, cannot be replaced by more intrinsically quiet concrete bridges. A computational model is described for the estimation of noise levels due to a train crossing a steel bridge. Despite the complexity and diversity of bridge structures, a highly simplified model of the bridge structure is used. An estimate of the noise emitted by wheel and rail is also incorporated. Comparisons with measurements on a number of typical bridges shows very good agreement. It is found that the increase in noise at a bridge is caused not only by the noise emission from the bridge structure itself, but also by increased noise radiation by the rail and a modified sound transmission from bridge to receiver. It is possible, in close collaboration with designers, to use the model in optimizing bridge structures. The model is also intended to complement the Dutch statutory prediction schemes for railway noise.