Improving the Nighttime Visibility of Signs and Workers in Road Work Zones in Japan

In Japan, work-related accidents at construction sites resulted in 487 fatalities and 27,193 injuries in 2005. The Ministry of Land, Infrastructure and Transport began devising more stringent safety measures to address those accidents in 2001, but standards for construction safety facilities vary from one construction site to another, and work zone safety improvement has been insufficiently studied. In previous studies, the authors surveyed traffic safety contractors and road users on their satisfaction with road work traffic safety measures. Both traffic safety contractors and road users reported the greatest dissatisfaction with the understandability of road work signs, followed by the nighttime visibility of traffic control personnel. The present study aims to improve the understandability of information displayed on road work signs and to examine measures to improve the nighttime visibility of traffic control personnel. This study suggests that clear signage that is not text heavy is the most effective at prompting drivers to change lanes. Also, in some cases it may be more effective to light traffic control personnel with aimed floodlights than with additional light-emitting devices.