行人和摩托车手是易受伤害的道路使用者，在道路交通碰撞（RTC）中比例过高。道路照明的一个假定好处是，通过对抗对天黑后发生的危险的视觉检测的损害，在天黑后减少RTC。优化道路照明的一种方法是只照亮那些光照水平和能见度是重要因素的路段。目前的研究使用RTC上环境光照水平的变化来调查视力改善可能产生重大影响的情况，以及道路照明成本更高的情况- 效益效益。对于摩托车驾驶员和行人RTC而言，与白天相比，黑暗中的RTC总风险显著增加，这表明道路照明可能具有整体效益。虽然黑暗对摩托车手的路口和行人的高速道路造成了特别的危害，但在这两种情况下，道路照明可能都不是有效的缓解措施，因此应考虑增加醒目性的替代方法。

Pedestrians and motorcyclists are vulnerable road users, being over represented in road traffic collisions (RTCs). One assumed benefit of road lighting is a reduction in RTCs after dark by countering the impairment to the visual detection of hazards that occur after dark. One way to optimise the use of road lighting is to light only those sections of road where light level, and hence visibility, is an important factor. The current study used change in ambient light level on RTCs to investigate those situations where improved vision is likely to have significant impact, and therefore the situations where road lighting is of better cost-benefit effectiveness. For both motorcyclist and pedestrian RTCs there was a significant increase in overall RTC risk in darkness compared to daylight, indicating that there may be an overall benefit of road lighting. While darkness was a particular detriment at junctions for motorcyclists and on high-speed roads for pedestrians, road lighting may not be effective mitigation in either case and therefore alternative ways of increasing conspicuity should be considered.