In Service Performance Of Highway Barriers PDF Download

Road barriers have been used as an effective countermeasure to prevent exposure of errant vehicles to both vehicles travelling in the opposite direction and to roadside hazards. The objective of this study was to evaluate the in-service safety performance of three types of road barriers (concrete barriers, steel W-beam guardrails, and high-tension cable barriers) in Indiana using cross-sectional analysis based on crash data. The quantitative evaluation was comprised of three components: 1) the effect of the road, barrier scenarios, and traffic on the barrier-relevant (BR) crash frequency, 2) the effect of the road and the barrier scenarios on the BR harmful events, and 3) the effect of the BR events and other conditions on the injury outcomes.The introduction of the BR harmful events linked the crash onset with its outcome. The three developed statistical models were connected through their inputs-outputs and followed the sequence of various BR events during the BR crash. This improvement allowed a more comprehensive and insightful analysis of the barriers' safety effects and a more efficient use of data. The injury outcomes were estimated for all the individuals in a crash rather than for the most severe outcome of a crash. Further improvement of the cost estimates was accomplished by utilizing hospital data.For median barriers, this study found that the total number of BR crashes was higher with the use of median barriers, mostly due to the introduction of collisions with barriers and an increase in the collisions after redirecting vehicles back to traffic. These undesirable effects of barriers were surpassed by the positive results of reducing hazardous events such as cross-median crashes, rollover events, and collisions with roadside hazards, which substantially reduced the number of severe injuries and fatalities.