ANALYSIS OF INTERSECTION CAPACITY AND LEVEL OF SERVICE BY SIMULATION

A procedure for applying computer simulation in evaluating the capacity and level of service of single, unsignalized intersections is presented. The process may also be used to study these features at signalized intersections. The Texas model for intersection traffic is especially suitable for this purpose because it (a) uses a detailed description of intersection geometry, (b) incorporates as many as 5 driver and 15 vehicle classes in the traffic stream, (c) simulates the behavior of each individually characterized driver-vehicle unit as it responds to its static and dynamic surroundings, and (d) presents summary statistics about the performance of traffic and traffic control devices at the end of any selected period of time. Capacity, which is the maximum traffic volume that can be accommodated under prevailing conditions on an intersection approach or by the whole intersection, can be determined through a successive approximation technique by using a few runs of the model. The level of service of an intersection operating under a specified form of control and carrying a given traffic volume can be defined in terms of recommended quantitative indicators such as average delay, percentage of vehicles required to stop, and percentage of vehicles required to slow to less than 16 km/h (10 mph). Four cases in which the model can be used to determine the capacity and level of service of unsignalized intersections are presented. /Author/