Effectiveness of Optical Speed Bars in Reducing Approach Speeds to Rural Communities

Abstract

Speed management has been a challenge in rural communities due to low budgets, and it is necessary to identify effective, low-cost approaches to reduce speeds. Accordingly, this research attempted to evaluate the effectiveness of optical speed bars (OSB) in reducing approach speeds on two-lane, rural undivided highways approaching small communities. Speed data were collected and analyzed before and after installation of the OSBs at five such sites. Effectiveness of the OSBs was evaluated using changes in mean and 85th percentile speeds under different categories by considering all vehicles, vehicle classification, days of the week, and time of day. Significant reductions in mean speeds and speed variance were observed at the end of the OSBs at four of the five sites, and one site showed no statistically significant change in speeds. Speed reductions were higher during daytime and weekdays. Higher speed reductions for two-axle vehicles were observed, with the exception of the Belvue test site. Speed increased in the opposite direction and at data collection points ahead of OSBs in the treatment direction, whereas there were reductions in speeds at the end of OSBs, indicating that OSBs seem to be effective in reducing approach speeds.