Speed reduction has traditionally been attempted by statutory speed limits.
Recent implementations of shared space schemes have delivered significant traffic speed reductions. The reductions are sustainable, without the need for speed limits or speed limit enforcement. In Norrköping, mean traffic speeds in 2006 dropped from 21 to 16 km/h (13 to 10 mph) since the implementation of such a scheme.
Even without shared street implementation, creating 30 km/h zones (or 20 mph zone) has been shown to reduce crash rates and increase numbers of cyclists and pedestrians. Other studies have revealed that lower speeds reduce community severance caused by high speed roads. Research has shown that there is more neighborhood interaction and community cohesion when speeds are reduced to 20 mph.
German research indicates that making one-way streets two-way for cyclists results in a reduction in the total number of collisions. In Belgium, all one-way streets in 50 km/h zones are by default two-way for cyclists. A Danish road directorate states that in town centres it is important to be able to cycle in both directions in all streets, and that in certain circumstances, two-way cycle traffic can be accommodated in an otherwise one-way street.
Two-way cycling on one-way streets
One-way street systems can be viewed as either a product of traffic management that focuses on trying to keep motorized vehicles moving regardless of the social and other impacts, such as by some cycling campaigners, or seen as a useful tool for traffic calming, and for eliminating rat runs, in the view of UK traffic planners.
One-way streets can disadvantage cyclists by increasing trip-length, delays and hazards associated with weaving maneuvers at junctions. In northern European countries such as the Netherlands, however, cyclists are frequently granted exemptions from one-way street restrictions, which improves cycling traffic flow while restricting motorized vehicles.
German research indicates that making one-way streets two-way for cyclists results in a reduction in the total number of collisions.
There are often restrictions to what one-way streets are good candidates for allowing two-way cycling traffic. In Belgium road authorities can in principle allow any one-way streets in 50 kilometres per hour (31 mph) zones to be two-way for cyclists if the available lane is at least 3 metres (9.8 ft) wide (area free from parking) and no specific local circumstances prevent it. Denmark, a country with high cycling levels, does not use one-way systems to improve traffic flow. Some commentators argue that the initial goal should be to dismantle large one-way street systems as a traffic calming/traffic reduction measure, followed by the provision of two-way cyclist access on any one-way streets that remain.
In general, junction designs that favour higher-speed turning, weaving and merging movements by motorists tend to be hostile for cyclists. Free-flowing arrangements can be hazardous for cyclists and should be avoided. Features such as large entry curvature, slip-roads and high flow roundabouts are associated with increased risk of car–cyclist collisions. Cycling advocates argue for modifications and alternative junction types that resolve these issues such as reducing kerb radii on street corners, eliminating slip roads and replacing large roundabouts with signalized intersections.