Effectiveness of static detour signage on motorways during road closures – An observational study

Road workers have raised concerns about the safety risks they face when installing static detour signs before a road closure. Their tacit knowledge is that many drivers ignore the signs. It is unknown whether road workers are correct, as the effectiveness of static detour signs on drivers’ route choices has not been researched. Therefore, this paper investigated the influence of static traffic diversion signs on drivers’ route choices during road closures on secondary roads adjacent to motorways in the Netherlands. The influence of static diversion signs was assessed by observing route choice and detour compliance around them. Two road closure cases were evaluated using cameras (Automatic Number Plate Recognition) and road detection loops. The two cases showed that roughly 40% to 60% of the cars affected by the closure do not follow the detour signs. So, although this paper finds that static signs affect route choices to some extent, road workers’ views seem correct: many drivers affected by road closures do not follow the signs. This study's qualitative explanatory model for non-compliance with these signs reveals many reasons, ranging from intended behaviour to ignoring the signs to various unintended reasons. Future research could improve understanding of drivers’ motivations, perceptions, preferences, and attitudes towards detour signage and, subsequently, route choice. Additionally, the influence of in-car navigation systems during road closures could be researched. These insights might lead to the implementation of safer, more effective measures to divert traffic during road closures.