Evaluation of the effectiveness of daytime running lights (DRLs)

Many studies have found that daytime running lights (DRLS) are effective in reducing daytime multi-vehicle crashes. From an Australian perspective, while studies exist using data from other jurisdictions, there has been uncertainty about how effective DRLs would be under Australian environmental conditions, which can differ from other parts of the world. In addition, in recent years DRLs have become a standard feature of many new vehicles. The objective of this work was to utilize Australian crash data to estimate the impact of DRLs on casualty crash risk reflecting the Australian crash population and local conditions. It also aimed to broadly examine the real-world crash-based effectiveness of DRLs currently present in the light vehicle fleet.

The study utilized police reported casualty crash data for crashes that occurred during 2010-2017. The analysis used induced exposure methods, which offers the potential to assess the relationship between crash risk and DRL fitment by intrinsically controlling for confounding factors.

It was found that DRL fitment can reduce the overall risk of being involved in a non-nighttime multi-vehicle crash where vehicle visibility may be a factor in crash causation by a statistically significant 8.8%. Estimated crash reductions were higher at dawn or dusk and in higher speed zones.

Results provide clear evidence that mandating DRLs on all new vehicles would likely lead to reductions in the overall crash risk of the fleet through accelerating fitment through the fleet.

DRL fitment can reduce the overall risk of being involved in a non-night-time multi-vehicle crash where vehicle visibility may be a factor in crash causation. Governments should consider a DRL mandate on all new vehicle models, including all variants to accelerate the process of fitment through the fleet. This would likely lead to reductions in the overall crash risk of the fleet.