Infrastructure causes of road accidents on the Yaounde – Douala Highway, Cameroon

The overall goal of this study was to determine the causes of road crashes related to road infrastructure parameters on the National Road No. 3 (N3) and provide measures to improve the safety of all road users. To achieve this, 225 accident reports for the years 2017 and 2018 were collected from the State Defense Secretariat. This accident data was analyzed using the crash frequency and the injury severity density criteria to obtain the accident-prone locations (7 critical sections and 2 critical intersections) and a map presenting these locations produced with ArcGis 10.4.1. A site visit of these locations was then performed to obtain the road infrastructure and environment data necessary to get which parameters are responsible for road crashes. Ten parameters that affect the safety of road users were obtained, namely inappropriate number of lanes and median width, inadequate shoulder width and absence of clear zone, unsatisfactory access control, poor state of guardrails, mediocre state of road surface, poor state of side drains, unequipped rest zones, presence of street vendors, inadequate intersection layout, and absence of lighting at intersections. To provide a convenient safety level, amongst other measures proposed are the establishment of a unique speed limit except at singular points, the conversion to a 2x2 lane road with raised median, the setup of a monitoring and maintenance schedule for roads, the increase of shoulder width and creation of clear zones, and proper signage, channelization and lighting at intersections.