Computerized Solution for Signalized Intersection Service Volumes

The 1985 Highway Capacity Manual defines level of service as a function of the average vehicular stopped delay. The complexity of the equation to calculate this delay, however, makes the determination of service volumes required to produce a desired delay very difficult. Simple computerized techniques can be used for intersections where permitted phasing is not provided. Iterative solutions are required, however, where permitted phasing is provided. An iterative procedure to determine initial estimates of the service volumes for each lane group required to produce a desired delay is described and verified. After the initial solutions are obtained, the shared lane groups are checked for de‐facto left‐turn lanes. If necessary, the computations are repeated for each of these lane groups assuming an exclusive left‐turn lane with permitted signal phasing.