Vehicle loading and effect on the Tsing Ma Bridge using WIM data

The Tsing Ma Bridge in Hong Kong is a suspension bridge with a main span of 1,377 m. The bridge deck carries a dual three-lane highway on the upper level of the deck and two railway tracks and two carriageways on the lower level within the bridge deck. The highway traffic condition and the vehicle loading effect on the bridge have been closely monitored by a Wind and Structural Health Monitoring System (WASHMS) since 1997. By using the traffic data collected by weigh-in-motion (WIM) stations of the WASHMS, the highway traffic condition and vehicle loading of the Tsing Ma Bridge are analysed in terms of vehicle traffic volume, vehicle traffic composition, axle load spectrum and gross vehicle weight spectrum. The measured axle load spectrum and gross vehicle weight spectrum are compared with the design spectrum. The strain data collected by 110 strain gauges installed at three sections of the bridge deck are analysed. A practical method in conjunction with the method proposed in BS5400: Part 10 is used to estimate the fatigue life of the bridge due to highway loading and railway loading. It is found that the contribution of road vehicles to fatigue damage is rather small compared with trains.