Placements Guidelines for Bridge Parapet Systems with Curbed Sidewalks

Abstract

There have been many studies regarding the safety performance of bridge parapet systems without curbs in the last few decades. However, since curbs are often necessary for certain reasons such as drainage, right-of-way reduction, or other functions, more research including curbs is necessary. Thus, this study focuses on the bridge parapet system on a sidewalk with a curb. The main objective of this thesis is to develop placement guidelines of bridge parapets on sidewalks with curbs for a pickup truck under MASH TL-2 and TL-3 conditions. MASH stands for Manual for Assessing Safety Hardware, and it is the latest set of guidelines for the crash testing of roadside safety features published by American Association of State Highway and Transportation Officials (AASHTO). For in-depth analysis, this research incorporates full-scale trajectory testing and computer simulations using finite element analysis. The full-scale testing in this study is between the sidewalk curb and vehicles to identify the trajectories of a passenger car and a pickup truck under MASH TL-2 conditions. Next, the simulation for a pickup truck is developed. Since this study incorporates the trajectory testing under TL-2 conditions only, the previous MASH TL-3 testing undertaken by California Department of Transportation (Caltrans) is used for the calibration of the vehicle model. Using the Caltrans research including the TL-3 crash test and the data received from the trajectory testing under TL-2 conditions, the pickup truck model is calibrated. The calibrated model is developed with two different curb profiles, an 8-inch tall and 2-inch offset curb and an 8-inch tall and 3-inch offset curb, under both TL-2 and TL-3 conditions. By analyzing the trajectories of these four simulations, the lateral distances of the parapet from the curb and parapet heights are studied to figure out the appropriate locations and heights of the parapet. Finally, after the parametric simulations are conducted with various parapet heights and locations, the placement guidelines for bridge parapet systems with curbed sidewalks are developed with regard to a pickup truck.