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This edition of Austroads News has a road safety focus. March saw the release of two significant reports examining setting speed limits and another about understanding crash types in urban areas. We also published reports about optimising arterial and managed motorway interfaces and the use of auxiliary brakes by drivers of heavy vehicles.

Model National Guidelines for Setting Speed Limits at High-risk Locations

This report provides model national guidance on implementing reduced speed limits on roads with high risk of severe crashes, which cannot be reasonably treated with cost-effective engineering treatments.  The model guidelines propose a speed limit setting process based on harm reduction (an intermediate step towards the Safe System). 

The guidelines recognise the mobility role of different road categories and functions, and incorporate the key high severe crash risk factors as criteria for reduced speed limits on road lengths that:

  • are narrow
  • have substantial levels of roadside hazards
  • have frequent intersections and access points
  • have curved or undulating alignment
  • have a history of high severe crash rates.

They also provide criteria for high-speed arterial intersections that:

  • have high traffic volumes
  • are located in outer metropolitan locations
  • have experienced a permanent change in traffic patterns, or
  • have a significant severe crash history.

The model guidelines aim to provide consistent speed limits on roads and intersections in response to high severe crash risk, while minimising the frequency of speed zone changes.
The objective of the project was achieved through review of the available research evidence and best practice in Australia, New Zealand and in other road safety leader countries.  The model guidelines were developed in close consultation with Australian road agencies.

Application of the model guidelines was trialled on selected routes and intersection approaches to ensure that they can be applied in an easy and efficient manner.
The intent of the model guidelines is to inform future revisions of relevant Austroads Guides on speed limits.

Download the report here.

Reducing Speeds on Rural Roads

Speed contributes to around 28% of all fatal rural crashes in Australia, and 31% in New Zealand.

In 2008, Austroads commenced a four-year research project on the topic of speed reduction in rural areas. The key objective of this research was to provide information to Austroads members on effective techniques to reduce speed and speed-related crashes in rural areas, particularly those involving engineering-based solutions. 

The research included a literature review and international review of expert opinion; the development of a strategy for future research to address gaps in knowledge; data analysis; site visits; consultation with industry; rural speed workshops; trials of new treatments; and development of guidance.

In March Austroads released the final report  for this project - a compendium of good practice to inform practitioners of the extent of the speed issue in rural areas and to provide guidance on effective actions that can be taken to reduce the incidence and severity of crashes on rural roads.

Detailed information is provided on almost 30 road engineering treatments that may be used to reduce speeds at key locations on rural roads. Information is presented on the speed and crash reduction effectiveness of commonly used treatments. These include advance warning signs, chevron alignment markers, and advisory speed signs at curves; advance warning signs and roundabouts at intersections; and advance warning signs and buffer zones on the approach to towns.

In the short term, speed reductions are likely to result in incremental improvements in safety. It is anticipated that in the longer term, Safe System objectives can be met through appropriate speed management used in combination with other system elements (safer roads, road users and vehicles).

Download the report here.

Understanding Run-off-road and Head-on Crashes in Urban Areas

Run-off-road (ROR) and head-on crashes share many similar characteristics. ROR collisions are one of the most common crash types, whilst head-on crashes generally result in more severe outcomes. To achieve a Safe System, it is important to identify factors that may reduce the incidence or severity of these crash types.

To achieve this:

  • a literature review was undertaken to identify previous investigations into factors associated with ROR and head-on crashes in urban environments, measures that may be used to prevent crashes, and the effectiveness of these measures
  • crash data over a five-year study period (2006–10) in urban ROR and head-on crashes in Australia and New Zealand were analysed 
  • site investigations were conducted at ‘high’ crash sites in Sydney, Melbourne, and Brisbane metropolitan areas, to identify factors that may have contributed to the occurrence or severity of ROR and head-on crashes.

Following consideration of the findings of the literature review, mass crash data analysis, and the site investigations, a number of safety measures were identified.

Factors found to be related to an increased incidence or severity of urban ROR and head-on crashes include:

  • driver characteristics: fatigue, younger, and male drivers have all been identified as at higher risk of these crash types
  • vehicle factors: older vehicles have been associated with higher incidence in these crash types
  • road design: steep downhill gradients leading into curves, multiple curves within a short distance and limited sight distances were amongst a variety of contributory road design factors identified.

The study identified avenues of future research including appropriate tree species for roadside planting, the role of vehicle age as a contributory crash factor, and how the roadside environment may relate to incidence of head-on collisions.

The report identifies short term safety measures that could be undertaken as part of a road maintenance program and more substantial improvements to be undertaken as part of a capital works or road safety program.

Improvements to be undertaken as part of road maintenance included improved road delineation, improved signposting, maintenance of roadside vegetation, and treatment of sight distance issues. More substantial improvements to be undertaken included treatment of curves known to be at risk, treatment of roadside hazards, speed reviews based on road geometry and roadside hazards.

Download the report here.

Optimising Arterial and Managed Motorway Interfaces

Signalised interchanges and ramp metering are major components of the interface between the arterial road system and the motorway system. The control systems of motorways and arterials are often treated as separate control components, which can introduce inefficient operations on both systems.

This project involved a survey of problematic interface sites throughout Australia and New Zealand. Four specific types of interfaces were studied: arterial roads adjoining motorway on-ramps; motorway off-ramps onto arterial roads; motorway-to-motorway interchanges; and motorways terminating at arterial roads.

This report examines four case study sites (one for each interface type) which currently or previously have exhibited inefficient traffic operations:

  • Blackburn Road/Monash Freeway Westbound On-ramp (Victoria)
  • Eastern Freeway Terminating at Hoddle Street and Wellington Street (Victoria)
  • M2/Epping Road Northbound Off-ramp (New South Wales)
  • Roe Highway to Kwinana Freeway Southbound Ramp (Western Australia)

From examination of the case study sites and discussion amongst jurisdictions, a set of principles, strategies and treatment options has been developed for each of the four interface types.

Coordinating the operations of motorways and arterials requires overarching strategies that manage the motorways and their adjoining arterials as single corridors and not as individual, separate facilities.

Download the report here.

Use of Auxiliary Brakes in Heavy Vehicles

This report reviews the use of auxiliary brakes by drivers of heavy vehicles on long and steep descents. The research was in response to a number of serious incidents involving runaway trucks on long, steep grades and continued noise complaints from the community.

The research included a substantial literature review, surveys of truck drivers and local governments, field testing, and the development of a simulation program to assess differential speed limits on long steep grades.

It is important heavy vehicle drivers understand how to correctly use the auxiliary brake system for their own safety and the safety of other road users. The report proposes a driver training framework which includes elements of safe, efficient and polite driving.

It also recommends that Australian regulators consider mandatory auxiliary brake system performance requirements for certain categories of heavy vehicles.

Download the report here.

Upcoming Workshops and Conferences

NEW 2014 Asia Pacific Intelligent Transportation Systems Forum
28-30 April 2014, Auckland New Zealand

NEW NeTC Industry Forum - Tolling Into the Future 2014
27-29 May 2014, Sydney Australia

Velo City Global Cycling Conference
27-29 May 2014, Adelaide, Australia

IPWEA Sustainability in Public Works
27-29 July 2014, Tweed Heads/Coolangatta, Australia

AITPM National Traffic and Transport Conference
12-15 August 2014, Adelaide Australia

26th ARRB Conference
19-22 October 2014, Sydney Australia

Austroads Bridge Conference
22-24 October 2014, Sydney, Australia