Increased transit service is widely regarded as an effective solution to traffic congestion, particularly because transit vehicles have larger capacity. Surface transit, however, operates in a different service paradigm, and may preclude the use of space by passenger cars or impose delay on traffic.

By adapting existing delay and queuing models, a model was developed to quantify negative externalities imposed on the network for various conditions found or implied on Fisher Avenue in Ottawa and Taunton Road in Oshawa, and evaluated for realism using VISSIM and AIMSUN. This model may support existing methods for evaluating marginal changes in transit service to maximize traveller throughput. The model extends to autonomous vehicles, ride-hailing services, and performance models.

The model shows that as the proportion of transit vehicles increases, the imposed delay may reduce arterial throughput, reducing road performance and traveller benefit, which can indicate conditions better served by grade-separated transit.