Effect of speed humps on injury consequences on trunk roads traversing towns in Ghana: A quasi-experimental study

BACKGROUND: Speed calming interventions have been employed globally as a road safety measure to curb outcomes of RTCs such as injuries and deaths. In Ghana, few studies have reported on the effect of speed calming measures on the severity of road traffic injuries. This study examined the effect of speed humps on the severity of injuries during RTCs on trunk roads passing through towns in Ghana from 2011 to 2020. METHODS: The study employed a quasi-experimental before-and-after study with controls design to answer the research questions. The study used both primary and secondary sources of data. Univariable and multivariable ordered logistic regression was used to examine the effect of speed humps on the severity of injuries during RTCs. RESULTS: The mean height, length and spacing of the speed humps were 10.9 cm, 7.67 m and 207.17 m, respectively. Fatal/serious/minor injuries were 35% higher at the intervention than the control settlements prior to installation of speed humps though not significant (adjusted OR (aOR)=1.35, 95% CI 0.85 to 2.14). A significant change in injury severity occurred after the installation of the speed hump devices. There was a reduction of 77% in fatal/serious/minor injuries at the intervention towns compared with the control towns (aOR=0.23, 95% CI 0.11 to 0.47). CONCLUSION: The findings present evidence suggesting that speed hump is an effective road safety measure in reducing the severity of road traffic injuries on trunk roads.