Interface analysis and design: improving heavy vehicle road safety barrier design

The Safe System Approach recognises the holistic paradigm of safer vehicles, safer roads, safer road users and safer speeds. However, failures in our road safety system continue to occur regularly because of breakdowns in system safety at various interfaces. The authors will present a series of papers, based on their experience with hundreds of crash investigations, road safety research, system design and applied interventions, examples of how formalised Interface Analysis and Design methods can be applied to improve road safety in all domains: road infrastructure, vehicles and road user behaviour. The particular case of heavy vehicle impacts into roadside, median and bridge barriers and design performance requirements is investigated as the first paper of this series. Described is the recent crash event on Melbourners Bolte Bridge on 17 May 2013 where an unloaded truck swerving in the far lane to avoid hitting a smaller vehicle, struck the bridge barrier at a high impact angle. Fortunately, while the barrier design withstood this impact, the collision also highlighted the need for a critical review of current bridge barrier design criteria, bridge speed and lane management for heavy vehicles. The conclusions are: barrier systems can now be designed and crash tests carried out to validate that they perform in a crashworthy manner at an affordable cost; the movement of trucks over bridges needs to be controlled in terms of speed and their location (kept to the left lane) relative to the bridge barrier depending on the barrier capacity; and truck drivers, heavy vehicle operators and regulators can play a major role in ensuring the barrier system is effective. That is, the interface of these elements need to be considered in concert.