Traffic-calming zones identified by road sign number 325 of the German Road Traffic Regulations (StVO) have proved successful since first being introduced in the 1980s. They have no recognizable shortcomings in terms of road safety and are largely accepted by all road users. Municipalities use road sign number 325 extensively in residential areas but also increasingly for shopping districts, streets in (historic) urban districts and local access or collector roads. However, it is clear that the objective of reducing the speed of traffic to walking pace in these zones is generally not achieved. In reality, average drive-through speeds are around 18 km/h, and speeds of over 35 km/h are rare. If consistent design principles are applied, in particular in terms of the use of speed-reducing elements such as chicanes or speed humps, good road safety results can be achieved for streets with a traffic volume of up to 4,000 motor vehicles a day. Avoidance of any structural demarcation between the traffic and the edge of the road space (curbs, for example) can be viewed as a critical element that has a direct impact on speeds. In residential streets, on the other hand, the design of the road space is less important. When accidents do occur in traffic-calming zones, non-motorized road users are particularly affected. Accidents involving pedestrians and cyclists are significantly more frequent in traffic-calming zones than those involving motor vehicles exclusively. Road safety problems are easier to identify at the interfaces between traffic-calming zones and the rest of the road network. These transitional points account for between 30% and 55% of the accidents in traffic-calming zones, with "turning-into/crossing" accidents involving motor vehicles accounting for the majority. The findings obtained from the video observations indicate that road users at the exits to traffic-calming zones are often uncertain as to who has priority. On the basis of this study, the UDV therefore has the following recommendations: * Provided they are well designed, traffic-calming zones can be a suitable means of improving safety and the experience of spending time in the road space for roads with traffic volumes of up to around 4,000 cars a year. This also applies to shopping streets, for example, in which pedestrians dominate due to the extent to which the edges of the road space are used. This kind of volume of motor vehicle traffic is currently not covered by the provisions of the German Road Traffic Regulations (StVO) regarding road sign number 325 (which assume very low levels of traffic). It should therefore be examined whether a suitable amendment to the regulations should be made. It should be examined whether this can be achieved with road sign number 325 or whether new signage is necessary. * Efforts to improve the design of the road space should continue to be made in order to bring speeds down to a level that is more suitable for pedestrians and cyclists. These include, in particular, no changes of level and the installation of speed-reducing elements throughout the zone. * The situation with regard to priority at the exits from traffic-calming zones must be clear to road users. * The official statistics also include other zones with reduced speeds, such as 30 km/h zones, parking lots or roads with a particularly low speed limit, in the same category as traffic-calming zones identified by road sign number 325. It is thus not possible to make statements about the traffic-calming zones identified by road sign number 325 based on the official accident statistics. It is recommended that this lack of precision in the data should be rectified. (Author/publisher)
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