The purpose of this study has been to set up a method by which certain urban traffic management schemes may be evaluated from a road safety point of view. The schemes considered are confined to restrictions in traffic movements: banning of certain directions at intersections and one-way or two-way in midblock. For this evaluation method, it has been necessary to develop a new concept: the traffic type, which is a traffic flow configuration of an intersection. This concept serves to classify the pattern of permitted and prohibited traffic flows at an intersection. The traffic types cover any combination of traffic directions at intersections. The term "traffic direction" is used to mean the movements of vehicles having a common origin and destination, either at an intersection or in midblock. Through a combination of accident data and traffic types it becomes possible - using an index called the accident value - to compare the accident risks associated with different traffic types. Other studies on one-way streets indicate that it is the midblock section which derives most safety benefit from one-way streets (which generally tend to reduce the accident rate), while intersections derive less benefit with non-signaled intersections as the weakest link. The accident value system is confined to non-signaled intersections. The ideas are illustrated by means of an example and comparisons with similar methods are given. In particular the traffic type concept is compared to a frequently used method consisting of a theoretical counting of conflict points at intersections. The work is based upon the right-hand rule of the road. (Author/publisher)
Samenvatting