Ballast Cleaning as a Solution for Controlling Increased Bridge Vibrations due to Higher Operational Speeds

Abstract

Dynamic load testing has become a common practice for condition assessment of masonry arch bridges and laying the foundation for their rehabilitation procedures, yet additional dynamic testing after rehabilitation is rare. Carrying out dynamic load tests before and after rehabilitation programs produces valuable results regarding the structural changes of the bridge. This paper tries to assess the effects of ballast cleaning on controlling the increased vibrations transmitted to the bridge structure due to increasing the operational speed. To do so, a 7-year-old masonry arch bridge is instrumented with accelerometers and dynamic load tests are carried out before and after ballast cleaning and results are compared. According to test results, vibrations with frequencies of up to 2 Hz are reduced by almost 16%, while those with frequencies between 25 and 1,3 Hz are reduced by almost 41%. It is concluded that from a vibration point of view, cleaning the ballast could increase the allowable speed of the trains on the bridge by 18 km/h.