A note on least time path computation considering delays and prohibitions for intersection movements

Most shortest path algorithms do not explicitly consider intersection movements in calculating best paths. However, in congested street networks, turning movement delays can be significant, and ignoring them may lead to the calculation of suboptimal or illogical paths. To reflect turning movments in practice, it is common to ‘explode’ the network representation for use with standard shortest path algorithms. This paper proposes a considerably more efficient approach; it consists of an extension to the commonly used forward star structure to represent the network including intersection movements and movement prohibitions. A label correcting shortest path algorithm is modified to take advantage of the proposed representation and calculate the least time paths in a computationally efficient way. The approach is implemented, tested and compared with existing techniques. The application of similar modifications to time-dependent and k-shortest path algorithms is also discussed.