Citation

Wright CC. Transp. Res. A Gen. 1986; 20(6): 463-476.

Copyright

(Copyright © 1986, Elsevier Publishing)

DOI

10.1016/0191-2607(86)90082-8

PMID

unavailable

Abstract

It is well known that the more complicated the layout of a junction, the greater the number of possible interactions between road users following different paths through the junction, and (other things being equal) the greater the risk of accidents. Unfortunately, there is no widely agreed classfication system for these interactions. Conventional textbook representations of the various points of conflict at a junction almost always omit several important categories (vehicle "shunts" and vehicle-pedestrian conflicts, for example). In addition, the lack of an accepted nomenclature for conflict types makes communication difficult--analysts often resort to verbal descriptions which do not easily translate across language boundaries, nor do they translate easily from countries where road users drive on the right to countries where they drive on the left. The purpose of this paper is to attempt a definitive classification and enumeration of conflict types at a junction with an arbitrary number of approaches. The analysis is based on topological principles rather than geometric ones, thus avoiding some of the problems associated with non-standard junction layouts where the definition of a simple manoeuvre such as "left turn" or a "right turn" may be ambiguous. In addition, a notation is proposed which would allow each individual interaction to be represented uniquely in terms of a "string" of characters. The notation is the same for all countries regardless of whether road users drive on the right or on the left, in the sense that it represents a given pattern in the first case and its mirror image in the second. Give the basic rules, it is a simple matter for the analyst to write down the string representation of any particular interaction starting from a geometrical diagram of the paths of the road users through the junctions, and vice versa. The string representation can be manipulated on a computer.