Preliminary Evaluation of the Bump at the End of the Railway Bridge

Bumps often develop at the interface between the bridge deck and the approach embankment of a railway bridge. The differential track movement at this transition zone creates higher impact loads, reduced bridge and embankment life, possible safety hazards, and higher maintenance costs. This study investigates the extent of the problem, typical maintenance expense, reasons behind the bump, and possible solutions. Based on a survey conducted to evaluate current practice, the bump problem affects about 50% of all railroad bridges and costs each railroad company an estimated $2,550,000 on maintenance. The typical slope for current bumps is equal to approximately 1:150. Using LS-DYNA, a 3-D, non-linear finite element program, a simple, rigid system was simulated to find the range of impact forces resulting from different bump slopes. A parametric study will be conducted in the future to examine the components involved and to optimize various solutions, such as approach slabs. The results from the entire study will help to minimize the bump at the end of the railway bridge.