Development of a MASH TL-3 Low-Profile Concrete Barrier

Abstract

A sight-distance problem is associated with use of 32-inch tall concrete longitudinal barriers, specifically in certain work zone locations and at nighttime. These 32-inch tall barriers can obstruct drivers’ eyesight, making it difficult for drivers to detect oncoming vehicles on the other side of these barriers and result in potential hazards. To address this sight-distance problem while protecting the errant vehicles, researchers developed a 20-inch tall low-profile portable concrete barrier (PCB) for use in low-speed work zones in the early 1990s, according to NCHRP Report 350 testing criteria. After that, several research projects were conducted to solve the high speed application of low-profile barriers, but most of them failed. In 2008, the new testing guideline Manual for Assessing Safety Hardware (MASH) was published as the updated criteria. Therefore, a low-profile barrier for high speed work zones needs to be developed and evaluated under MASH. In this research project, a new low-profile PCB was successfully developed for high speed application. This low-profile PCB was designed with a T-shaped profile with a height of only 26 inches and was a free standing barrier. Sight-distance obstruction problem was evaluated and a simplified experiment was conducted on 24 and 26-inch tall barriers. Finite element simulation analysis was conducted to determine the shape of the new barrier. Two different cases were considered for each profile concept—with and without impact tire disengagement—to represent the extreme tire behaviors during the impact event. Detailed simulations were conducted to predict the crashworthiness of the T-shaped PCB. Two successful full-scale crash tests were implemented according to MASH Test Level 3. The barrier model was then modified and validated based on the test results.