Friday, 21 August 2020
Austroads’ updated edition of Guide to Road Design Part 6: Roadside Design, Safety and Barriers includes a new process to evaluate roadsides and in particular the relative safety benefits and risk associated with different road environments, different speeds and the spacing and offset of hazards.
The information in Guide to Road Design Part 6 enables designers to assess the risk posed by roadside hazards, establish the need for treatment, and determine the most appropriate treatment.
David Bobbermen, Austroads Safety and Design Program Manager, says the new procedure encourages risk assessment at the network level to achieve the best network outcome from roadside risk mitigation treatments and is a completely different way to think about roadside design.
“The new procedure is primarily based on the determining the Network Roadside Risk Intervention Threshold (NRRIT), which is set by a jurisdiction within their economic capability and independently of project requirements.”
“This NRRIT is the level of risk which, if exceeded, requires roadside risk mitigation treatment throughout programs and in the delivery of projects. In this way, the road agency can demonstrate that treatments are being directed to achieve the best network road safety outcome. This is because independent project decisions of whether to treat a roadside cannot guarantee that the best outcome is achieved given road agency resources,” David said.
The key aspect of this work which has made this process simple to undertake, is the production of graphs which facilitate extremely quick assessments.
Austroads consultant, Professor Rod Troutbeck says the graphs are presented to cover most of the roadside risk scenarios for both urban and rural environments. “The procedure has utilised contemporary risk evaluation methodologies using exposure, likelihood and severity metrics to establish this simple process. It will enable the consistent identification of treatment locations across programs and projects.”
The Guide also presents designers with a range of treatment options they can use to reduce risks including:
- installing barriers or audio-tactile line markings
- changing the cross-section (including the use of wide medians and median barriers)
- removing or relocating the hazard
- reducing the impact severity posed by the hazard
- improving the delineation of the road
- accepting the risk of the untreated hazard where the frequency of hitting the hazard and severity are both low.
“Another significant change in the guide relates to the use of clear zones which is now considered as a treatment option, and not a measure to decide whether to treat a hazard or not” David said.
The updated Guide and a report detailing the research informing the changes can be downloaded from Austroads’ website at no charge.
Download
Guide to Road Design Part 6: Roadside Design, Safety and Barriers
Background to the Development of the 2020 Edition of Guide to Road Design Part 6
Join us for two webinars on the new guidance. Tuesday, 22 September 2020 The first session will be focused on user guidance, including the practical application of the new method. The webinar will describe the new procedure for evaluating a rural road network, how policies will influence decisions and how the Network Roadside Risk Intervention Threshold can consistently delineate road sections where treatments are required. The webinar will also provide the basis of the procedure by using a simpler example so that participants can appreciate its broader application. The example will demonstrate how risk graphs, based on contemporary knowledge, can be used to expedite the assessment procedure. Tuesday, 6 October 2020 The second webinar will describe the procedure’s background in more detail explaining the concepts and research behind it. |