Roadworks zones: Increasing safety for roadworkers and drivers
iMOVE’s Working near traffic: Work zone end of queue study, carried out with Transport for NSW and Deakin University’s Safe Future Mobility Research Lab, has been completed and its final report is available for download below.
Partners with iMOVE on this project were the Department of Transport (WA), Main Roads Western Australia, the University of Western Australia, and the Planning and Transport Research Centre (PATREC).
Background
End of Queue (EOQ), or back-of-queue crashes in most cases can be described as rear-end crashes, where a following vehicle impacts the rear of a vehicle in front.
Traffic queues at the end of queue (EOQ) location of roadwork sites are often associated with rear-end crashes, posing risks to roadworkers and motorists alike.
The specific objective of the project was to address the question, “Which traffic control measures are most effective in reducing the frequency/occurrence/severity of injuries at end of queue roadwork sites?”
This project accomplished this through the construction of an evidence base in which the effectiveness of different traffic management treatments to reduce the frequency and/or severity of injuries associated with EOQ crashes at roadworks was tested.
Methodologies
The research began with a literature review, looking at best practices in EOQ risk management worldwide. This was followed by consultation with international experts and local industry stakeholders.
From this, a list of 25 EOQ treatments was compiled for the purpose of conducting field trials. Examples of those treatments include:
Primary countermeasures
- Queue warning systems
- Speed limit systems
- Portable rumble strips
Supporting countermeasures
- Average speed safety cameras
- Lane narrowing
- Chevron headway markings
- Dynamic lane merge system
Heavy vehicle countermeasures
- Advanced driver assistance systems
- Crash warning system
- Autonomous emergency braking
- Blind spot warning system
- Thermal imaging systems
- Heavy vehicle radio communication
Other considerations
- Review traffic guidance scheme methodology
- Public education campaigns
- Roadwork zone safety rating system
- Zero-harm roadwork zones
- Connected vehicle technology trial
Crash data coding tool implementation
Field trials
Of those 25 EOQ treatments, 33 combinations of them were trialled in 13 roadworks zones across NSW. Trial data were collected for 116 days in total using automatic traffic counters and radar devices for speed data collection, video cameras for near-miss data collection, and roadside surveys with drivers.
Data were analysed using statistical ‘before-after evaluation’ methods to examine the effectiveness of the treatments in terms of:
- reduction in excess speed (i.e., speed above the posted speed limit),
- reduction in the probability of speeding
- impact on rear-end crash risk, and driver views on the treatments’ effectiveness and their future use.
Measures were compared across two study conditions:
- with EOQ treatment; and
- without EOQ treatment (i.e., baseline condition).
The final report provides details and findings for all 25 treatments, across all 13 trials.
Results
Some of the highlights of the treatment results include:
At the beginning of the advance warning area (around the first speed reduction sign):
- The treatments 15 (police presence), 16.2 (ESeries Condition 2), and 9B (UHF Radio – Manual broadcast) produced ‘large’ reductions (more than 2 km/h) in excess speed (i.e., speed above posted speed limit).
- These treatments also produced ‘very large’ reductions (more than 10%) in the probability of speeding in this area.
Reduction in rear-end crash risk:
- Conclusive results on reduced crash risk were found for Treatments 16.2 (ESeries Condition 2), 16.5 (ESeries Condition 5), the combination of 16.5 and 15 (ESeries Condition 5 and Police presence), and the combination of 16.5, 10.1, and 15 (ESeries Condition 5, Rumble strips Condition 1, and Police presence). All other treatments were associated with an increase in crash risk or inconclusive results.
Radar Activated Speed Sign (RASS)
- Roadside survey results showed that more than 80% of drivers noticed the RASS as they drove into the work area. The treatment received overall positive feedback from the drivers. The drivers agreed that the treatment is effective in reducing rear-end collision and most drivers were happy to see this treatment being used in future sites.
Police presence
- Police presence was found to significantly reduce the amount of excess speed (i.e., the speed above the posted speed limits) across all speed measurement points.
- Overall, police presence on site was associated with reducing both the excess speed and speeding cases throughout the work zones.
Recommendations
Based on the results, the The ‘most effective’ and ‘moderately effective’ treatments from this study are recommended to be used in future worksites.
The evaluation methodology’s short-term nature did not allow for the examination of any potential novelty effects of the studied EOQ treatments. Future research should look into longer-term trials of the treatments to examine their long-term effects beyond any novelty effects.
In addition, while light vehicle drivers were quizzed via a roadside survey, future research should further examine the perceptions of heavy vehicle drivers.
Download the final reports
Download your copies of the final reports from this project by clicking the links below.
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