Risk to workers or vehicle damage: What makes drivers slow down in work zones?

Objective: Speeding in work zones is common and poses significant safety hazards to motorists and workers. Previous studies have demonstrated that speeding is reduced when workers are visible to the drivers, suggesting that concern for the safety of workers influences drivers' speed choice. Conversely, the extent of speeding when workers are not visible suggests that drivers underestimate the increased risk of crashes or other damage to their vehicles associated with the poorer road conditions common at roadworks (loose surfaces and debris, narrower lane width and drop-offs etc.). To better understand the factors influencing drivers' speeds in work zones, this paper examined the extent to which drivers' speed choices are influenced by their perceived likelihoods of injuring workers and damaging their own vehicles.

Methods: Driver-nominated speeds and perceived likelihoods of worker injury and vehicle damage were collected in an online survey of 405 drivers from Queensland, Australia, by showing photographs of 12 real-world work zones. The data were analyzed using regression techniques to examine the factors influencing driver-nominated speeds and likelihood of speeding.

Results: The results supported the hypothesis that both drivers' perceived likelihood of injuring workers and damaging vehicles strongly influence their nominated speeds (p < 0.001). Young and middle-aged drivers nominated 2.5-6.3 km/h higher speeds than older drivers (p < 0.001). Car drivers who also held truck licenses nominated 4.5 km/h higher speeds (p < 0.001) and 81% higher odds of nominating speeds higher than posted limits (p < 0.001) than car-only licensed drivers. Drivers nominated lower speeds at road curves (12.1 km/h lower speed and 53% lower odds of speeding, p < 0.001), if adjacent areas of travel lanes were unpaved or had loose materials (11.5 km/h lower speed and 66% lower odds, p < 0.001), and when workers were visible in work zones (1.4 km/h lower speed, p = 0.004, and 27% lower odds, p = 0.041).

Conclusions: In addition to driver demographic and work zone characteristics, drivers' perceptions of safe speeds depend on their perceptions of the likelihood of worker injury and vehicle damage at work zones. These findings suggest that interventions to heighten drivers' perceptions of the likelihood of damage to their vehicles may be useful in moderating speeds at roadworks.