Potential Reductions in Road Fatalities and Injuries From Reducing Speed Limits to Recommended Safe System Speed Limits in Low- and Middle-Income Countries

Background: Speeds influence road safety by reducing both the likelihood and severities of vehicle-vehicle conflicts and conflicts among vehicles, cyclists, and pedestrians. Guidelines for setting speed limits can be derived from the safe system principles in which safe speeds are scientifically set at a point which will eliminate deaths and serious injuries.Method: This paper analyzes the potential road safety benefits of reducing current unsafe speed limits in low- and middle- income countries to recommended safe system speeds (i.e. 30kph for urban roads, 70kph for rural roads and 90kph for motorways) based on Nilsson’s power model. These benefits are calculated in terms of reductions in crashes and injured victims for different injury severity levels and road environment. Economic benefits of reducing fatalities and serious injuries are also estimated based on the iRAP methodology.Findings: The results indicate significantly high reductions in road trauma resulting from the reduction in speed limits with fatal crashes reducing by 4% to 44% depending on the road environment and region. The highest benefits are estimated to be on urban roads owing to the greatest proportional drop in speed limits in this environment. Regional analyses indicate that South Asia region has the greatest potential reductions for all types of crashes and injuries on rural and urban roads, while Europe and Central Asia region has the greatest potential reductions on motorways. A total of US$ 91 billion or 0·37% of GDP in LMICs is estimated to be saved from the reduction in fatalities and serious injuries, with Africa region having the highest economic benefit relative to its GDP (0·47% of GDP).Interpretation: Reducing current unsafe speed limits to recommended safe system speeds will deliver substantial reductions in road crashes and injuries of all severities in all road environments. In practice, it is recommended that this be accompanied by effective sustainable speed management measures including suitable engineering treatments, automated speed enforcement, police enforcement and vehicle technologies such as speed limiters to ensure drivers’ compliance and achieve profound road safety benefits.Funding Information: Preparation of this paper was supported by two of the donors to the Global Road Safety Facility: UK Aid and Bloomberg PhilanthropiesDeclaration of Interests: None