Overheight Collision Protection Measures for Bridges

Low clearance bridges are susceptible to collision with overheight vehicles. Collisions of overheight vehicles can cause fatalities and injuries to the drivers and passengers of the overheight vehicles, and damage to bridge girders. The repair of the damaged bridges can be costly and time consuming. Overheight collision has become a significant cause for the damage of bridges and the number is expected to rise. A previous work by the authors showed that a protection system called bridge bumper can be designed that maximizes the energy absorption and decreases the likelihood of damages and fatalities. The current work presents the full scale implementation of the bridge bumper to a realistic bridge subjected to overheight collision with a heavy vehicle. A detailed Finite Element (FE) model of the bridge impacted by overheight vehicle is simulated. The unprotected and protected bridge with bridge bumper is analyzed by a full scale non linear transient analysis. The key parameters such as material and geometric properties of the bridge and bridge bumper are varied. The protection system consists of a plate made of steel to distribute the impact energy over a large area called stiff guard (SG). Energy absorbing material (EAM) are used to mitigate the effect of collision. Two materials viz. low density aluminum and visoeleastic material are investigated to maximize the absorption capacity. The system can be designed for any given impact scenario. A realistic impact scenario is simulated and the applicability of the protection system is shown. This is a novel system for the protection of bridge girders from overheight collision. It is a fairly cheap system when compared with the repair and closure costs. It is easy to manufacture, assemble and impalement on the bridge girder. The research can be further extended for the protection of bridge pier, building column against accidental collision or terrorist attacks.