Most of the evidence examined in this review supports the crucial role of public policy in encouraging bicycling. Substantial increases in bicycling require an integrated package of many different, complementary interventions, including infrastructure provision and pro-bicycle programs, supportive land use planning, and restrictions on car use.
Safety in Numbers is the observation that the risk of an individual pedestrian or bicyclist being hit by a motor vehicle decreases as the number of pedestrians or bicyclists increases, respectively. This idea runs counter to what one might expect — that the more pedestrians and bicyclists there are, the more collisions with motor vehicles will occur. Data show there is not a proportional relationship between these two variables. In fact, the safety in numbers relationship has been observed across a wide range of geographic study areas, from individual intersections to continents,  in the U.S., Europe, and Australia.