A frequency based transit assignment model that considers online information and strict capacity constraints

This paper proposes a frequency based transit assignment model that accounts for online information and strict capacity constraints. A heuristic is proposed to solve the problem, which first applies an unconstrained transit assignment procedure and then handles only the over-loaded transit line segments, re-assigning the surplus passengers. The developed procedure is efficient, requiring very short running times compared to existing capacity constrained transit assignment models. The model assumes passengers receive online information of both predicted arrival time and occupancy condition. Two cases of occupancy information are considered: (1) passengers are informed of the vehicle occupancy, and may change their route selection accordingly, (2) passengers have no occupancy information and in case their boarding is denied, they are enforced to choose a later departing alternative. The model is applied for the Winnipeg network, and as expected the inclusion of capacity constraints increases the average travel time compared to the unconstrained model. However, prior knowledge of the occupancy condition was found to reduce the additional travel time. This result emphasizes the potential benefits of providing occupancy information to passengers.