The Marcytown - Rivertown corridor was served by 3 bridges, according to the attached map. The bridge over the River on the route directly connecting Marcytown and Citytown collapsed, leaving two alternatives, via Donkeytown and a direct. Assume the travel time functions Cij in minutes, Qij in vehicles/hour, on the five links routes are as given.
Marcytown - Rivertown Cmr = 5 + Qmr/1000
Marcytown - Citytown (prior to collapse) Cmc = 5 + Qmc/1000
Marcytown - Citytown (after collapse) Cmr = ∞
Citytown - Rivertown Ccr = 1 + Qcr/500
Marcytown - Donkeytown Cmd = 7 + Qmd/500
Donkeytown - Rivertown Cdr = 9 + Qdr/1000
Also assume there are 10000 vehicles per hour that want to make the trip. If travelers behave according to Wardrops user equilibrium principle.