Citation

Wright CC. Transp. Res. A Gen. 1985; 19(3): 219-226.

Copyright

(Copyright © 1985, Elsevier Publishing)

DOI

10.1016/0191-2607(85)90011-1

PMID

unavailable

Abstract

Most traffic engineers are familiar with the term 'geometric delay' as applied to roundabouts. The delay comes from the geometric layout, which forces a driver to slow down and deviate from a straight path, irrespective of whether there are any other vehicles using the roundabout at the time. It accounts for a substantial proportion of all vehicle delay at roundabouts, and is regarded as an important factor in the economic evaluation of roundabout schemes. Pedestrians are subjected to delay in a similar way, at a wide variety of locations and for a number of different reasons. However, very little is known about the magnitude of this delay, and in practice it is usually ignored by planners and engineers. Some of the more obvious features of the road environment which deflect people from their natural paths are guardrails, pedestrian crossings, and, of course, roundabouts. However, the most pervasive feature is the carriageway itself. Even when there are no vehicles in sight, most pedestrians cross the road approximately at right angles, because this minimizes the time during which they are exposed to risk. On an urban street network, where the shortest route usually runs diagonally across the street from one junction to another, this entails an appreciable extra walking distance. The average excess distance can be calculated as a function of street width and separation for a rectangular grid network. The object of this article is to review what appear to be the main sources of geometric delay to the pedestrian and to estimate the magnitude of the delay in typical cases. It turns out that overall, geometric delays account for a small, but appreciable, component of the pedestrian journey time in an urban area.