Studies of injury epidemiology, injury severity, or crash, collision, or fall rates (including before-and-after studies) were eligible for inclusion provided they considered some aspect of the infrastructure as a determinant or predictor of cycling safety and they investigated a relationship between transport infrastructure (designed for motor or non-motor vehicle use) and a clearly defined measure of cycle safety (injury, injury severity, or crash, collision, or fall rate). Studies had to be conducted in an Organisation for Economic Co-operation and Development (OECD) country. Those studies in which injuries or crashes occurred during bicycle racing, off-road mountain biking, tricks or trials riding or play, those of injuries not related to a crash, in which the rates (per exposure or riding time) were not calculated or in which the infrastructural determinants of injuries were not considered, those reporting subjective perceptions of safety or risk, and those that examined only conflict between cyclists and other road users, without identifying crashes or injuries, were excluded.
The majority of included studies were published after 1994 and focused on junction-related incidents (at roundabouts or junctions) or transport infrastructure-related safety (on major or minor roads with or without marked cycle paths, footpaths, cycle paths, or paved or unpaved trials and surfaces). The outcome measures varied; the majority were police or hospital reports, or cyclist surveys. Most of the studies were carried out in North America or Europe.
The authors did not state how many reviewers selected studies.