16 pagesInternational audienceIn network assignment models of urban transit, traffic congestion has been modelled either as vehicle congestion along the route track, or by reducing the service frequency with respect to excess flow of passenger arrivals. A third type of congestion has been modelled by Leurent (1), (2): that of seat congestion, because being seated or standing make distinct on-board states for a transit rider, resulting in distinct discomfort costs, with potential influence on route choice on the transit network. The paper has a twofold objective of, first, providing a concise statement of the seat congestion model, and second, reporting on its application to the Paris metropolitan area – a problem of very large size. The model makes explicit the residual set capacity and its evolution at any stage along a service line; the priority rules amongst riders depending on their order of arrival in the competition to get a seat; and the randomness in leg cost to the rider. Line algorithms and consistent network algorithms are provided
