Saving Lives Together

Papers about road infrastructure

As part of the Safe System, the Safe Roads and Roadsides cornerstone involves improving road infrastructure by:

  • Designing and maintaining roads and roadsides to reduce the risk of crashes occurring and the severity of injury if a crash does occur.
  • Providing a transport system that supports safe outcomes.
Metropolitan intersection safety project (2016-2017)

Killed and serious injury (KSI) crashes at intersections are a priority area for the Road Safety Council. The aim of the research was to address this crash type through a three staged research  project.

This included:

  • Stage 1 - resulting in the identification of risk factors.
  • Stage 2 - ranking of high risk intersections.
  • Stage 3 - recommendations of appropriate counter-measures to address these areas.

A summary of each report is detailed below.
Stage 1 report
Risk factors for killed and serious injury intersection crashes in metropolitan Perth: 2006-2015 (September 2016)

This study aimed at identifying risk factors for KSI intersection crashes in the Perth metropolitan area of WA from 2006 to 2015. Crash data from the Integrated Road Information System (IRIS) was modelled, to identify risk factors for crashes. The risk factors identified included:

  • A crash on the weekend.
  • At night time.
  • At non-level intersections.
  • At 3-way and 4 or more-way intersections versus roundabouts.

The research found that factors that reduced the risk of KSI crashes included rainy conditions, signalised traffic controls and multiple versus single vehicle crash types.

Stage 2 report
Identification of high risk metropolitan intersection sites in the Perth metropolitan area (December 2016)

The second tranche of research identified and ranked 60 high risk intersections in the Perth metropolitan area to determine the intersections that required the most urgent attention.
Stage 3 report
Optimal resource allocation recommendations for safety treatments at Perth metropolitan high risk intersections  (September 2017)
The final stage identified appropriate countermeasures for treatment of the high-risk intersections and allocated a cost and estimated reduction in the KSI metric using the Main Roads WA (MRWA) Crash Reduction Matrix. The suggested treatments range from grade separation or widening of bridges to modifying signals, adding lanes, installing roundabouts and extending turn pockets.

Road safety benefit
This research was beneficial to the extent that the report:

  • Provides a priority list of sites and counter-measures, which could be addressed via the Metropolitan Intersection Crashes (MIC) Program (administered via MRWA).
  • Estimates potentially reductions in KSI crashes, dependent on investments.

Stage 1 report Stage 2 report Stage 3 report

Improving curve delineation: A review of the literature and investigation of crashes on midblock curves in WA 2007-2011 (2014)

This research looked at the crashes occurring on curved roads in WA. The aim of this research was to examine ways to improve curve delineation, to make the curves safer.

The analysis of crashes on midblock curves in WA 2007-2011 highlighted the involvement of higher speed zones, alcohol and younger, less experienced drivers.

The research found that enhancing curve delineation can potentially improve this crash type and recommended:

  • A review of information and information sharing with asset holders (local Government and MRWA).
  • A trial of the Chevroflex Chevron Alignment Marker in identified high crash frequency locations.

Road safety benefit
The research found that there are some cheap but effective ways to improve the safety of curves through pavement markings and markers on posts. There are also some effective but more expensive ways to make drivers aware they are coming into a curve, including raised pavement markers and flashing beacons.

Improving curve delineation

An investigation of pedestrian crashes at traffic intersections in the Perth CBD 2008-12 (2013)

The aim of this research was to examine pedestrian crashes at traffic intersections in the Perth Central Business District, 2008- 2012, in order to identify potential risk factors, including the recent conversion of signalised intersections from ‘exclusive’ to ‘parallel’ walk.

For the period analysed, the research found that approximately 2% (n=88) of traffic crashes occurring at intersections in the CBD reported to WA Police during the study period involved collision with one or more pedestrians. Younger and older age persons are more frequently involved in pedestrian crashes, with other evidence attesting to the greater involvement of males than females.

Around six in ten vehicles collided with pedestrians as they were travelling straight ahead, with a further three in ten colliding with pedestrians as they attempted to turn left or right.

The research recommended:

  • Speed zoning high pedestrian areas to 30km/h.
  • Median refuges.
  • Trials of measures such as longer crossing times and countdown timers.

Road safety benefit
This research has the following road safety benefits: it provided clarity on the profile of pedestrian crashes in the Perth CBD and provided recommendations which support a need to review current speed management strategies in high pedestrian areas and undertake trials in WA.

Pedestrian CBD crashes

Designing safer roads to combat driver errors – rural crashes (2013)

The aim of this research was to consider driver behaviour including driver error and deliberate unsafe behaviour in rural areas and then identify counter-measures to address this.

Road safety benefit
The research provided an overview of driver error crashes and potential counter-measures. Many countermeasures were identified in the literature to address driver error in WA along remote and regional areas, including:

  • Perceptual countermeasures such as transverse lines and wide centreline marking.
  • Physical measures such as rumble strips and increased lighting.
  • Lane widening and edge marking.
  • Dynamic speed alert signs and speed reductions.

Designing safer roads to combat driver errors -rural crashes

An investigation of urban run off road crashes in WA 2005-2009 (2013)

The aim of this research was to consider the epidemiology of single vehicle run off road crashes in the urban area and look at a range of safe road and roadside countermeasures to reduce the incidence of crashes and injury severity.
Two crash types occurring in the Perth metropolitan area 2005-2009 were selected for analysis:

  • Vehicles running off the road and crashing into an object or involved in a non-collision (rolling over) (n=12,843).
  • Vehicles running off the road and colliding with a pedestrian off carriageway (n=18).

The research found that:

  • Single vehicle run off road crashes in the metropolitan area accounted for nearly six in ten crashes of this type across WA.
  • Compared with the regional and remote areas of WA, two to 3.5 times as many single vehicle run off road crashes occur in the metropolitan area. However, when the injury severity of these crashes is considered, this factor is reduced to 1.8 to 2.3 times.
  • Risk factors for crashes were higher speed zones and curves, younger age, being male and alcohol.
  • Factors that reduce crashes, include braking and crash avoidance technology in vehicles and lower speed zones.

The research recommended:

  • Incentivising buying safe vehicles with technologies to minimise run off road crashes.
  • Reducing vehicle speeds.
  • Identifying black spots and using counter-measures such as audio-tactile edge lining, creating clear zones and clearing roadside hazards, improved curve alignment, improved lighting and the use of barriers.

Road safety benefit
This research has provided visibility into the risk factors associated with single vehicle run off road crashes in WA. Furthermore, it has made locally appropriate recommendations to the criteria and process supporting the identification of high risk road lengths in the future as well as suggestions to improve the system that supports WA drivers (i.e reduced travel speeds on specific routes, incentivising purchase of safer vehicles and ongoing investment in programs that support safe roads and roadsides).


Urban area crash report

An evaluation of the effectiveness and cost-effectiveness of a rural run-off road crash program in Western Australia (2016)

Single vehicle loss-of-control run-off-road crashes are a significant issue in regional and remote Western Australia, where they accounted for almost 60% of all road deaths and serious injuries from 2008 to 2012.

The aim of this research was to evaluate the nearly 1000 kilometres of rural WA roads that were treated under the rural Run-off-road Crash Program between 2012 and 2015, which utilised the treatments 'shoulder widening and/or sealing' and 'audible edgelines'. The preliminary evaluation performed by C-MARC at the end of 2016 found the WA program to reduce run-off-road crashes (all severities) by 35.5% and run-off-road killed or serious injury (KSI) crashes by 25.5%.

Road safety benefit
The research found that investment in regional roads is improving road safety. The research also noted that the Run-off-road Crash Program performed well in economic terms. In relation to the net economic worth of the program, the net present value and the benefit-cost ratio across the treated sites were estimated to be $100.2 million and 2.1 respectively, indicating cost savings to the community of $2.10 for each $1 invested.

An Evaluation of the Effectiveness and Cost-effectiveness of a Rural Run-off-road Crash Program in Western Australia