This paper presents a simulation model, in which delays at priority junctions can be determined under conditions of partially constrained, non-stationary traffic of varying intensity. Traffic is 'partially constrained' if not all drivers can maintain their desired speeds, due to the presence of other vehicles, and 'nonstationary' if its intensity varies with time. Within this context, any possible traffic streams at intersections of two two-lane roads can be considered. The method developed here will contribute to the decision whether to introduce traffic signals at an intersection. Simulation has been used to evaluate the influence of partial constraint on delay; some example simulation results are discussed in order to provide a first impression of the traffic intersection, for the example of a priority junction of two two-lane rural roads. The following conclusions are reached: (1) under partially constrained traffic conditions in the major road, the average delay decreases significantly in comparison to free-flow major stream traffic, whereas partial constraint on minor streams has insignificant effects on average delay; (2) a rapid increase in average delay compared to free-flow traffic occurs only under conditions of higher minor road traffic volume for partially constrained non-stationary traffic; (3) for constant total traffic volume on the major road, delay is reduced as the difference of directional traffic volumes decreases.
Abstract