Evaluation of Narrow Median Wire Rope Barrier Installation on Centennial Highway, New Zealand

Abstract

This paper reports on the performance of a wire rope barrier on a narrow median installation on Centennial Highway, New Zealand. Since the time the speed limit was reduced from 100km/h to 80km/h and the wire rope median barrier was installed, no fatalities or serious injuries have occurred. The median barrier was introduced in two stages and has been very successful in reducing road trauma. Prior to stage one the average annual social cost of crashes on Centennial Highway was $5,796,889. This has since reduced to an average social cost of $65,400 per year. Surveillance of the Centennial Highway median barrier showed that vehicles generally sustained relatively little damage when they struck the barrier and were often observed to drive away after the impact. Drivers also tended to travel more centrally within their lane with the barrier in place. While the narrow median on Centennial Highway has resulted in an increase in maintenance costs due to impacts on the wire rope barrier, this cost has been significantly offset by reductions in trauma costs. This paper presents a number of challenges that needed to be overcome to construct the narrow median wire rope barrier and evaluates the success of the barrier in reducing road trauma along this section of state highway.