Methodology for assessement and design of arrestor beds

Abstract

In a long descending slopes heavy vehicles might lose control and runaway downgrade. To mitigate the potential damage, exist several systems that permits heavy vehicles leave the lane and stop. These systems are known as Arrestor Bed (AB). Design Standards consider the geometric criteria proposed by AASHTO (2001) standards. AASHTO recommend a constant value of the design speed for AB. Also, recommends general criteria to evaluate the need and location of an AB. The standards does no proposed analytic procedures to the designer assess the need and location of an AB. In this work, a methodology of analysis and design of AB is proposed. The methodology applies analytic criteria to evaluate the need and the location of an AB based on the brake temperature profile of trucks developed by Bowman (1989). Also, an energetic based method to estimate speed profile and design speed is proposed. The method consider the slope and the length of the slope. The proposed methodology allows to the designer to solve the main questions in the design of AB: ¿It is necessary an AB? ¿Where to locate it? ¿What is the design speed?. To illustrate the proposed methodology an AB at present in operation was analyzed. It was determined that is necessary to relocate de AB, to design an impact attenuator, and to post a limit speed for heavy vehicles in the downgrade lane.