Flows in dynamic networks with aggregate arc capacities

Dynamic networks are characterized by transit times on edges. Dynamic flow problems consider transshipment problems in dynamic networks. We introduce a new version of dynamic flow problems, called bridge problem. The bridge problem has practical importance and raises interesting theoretical issues. We show that the bridge problem is NP-complete. Traditional static flow techniques for solving dynamic flow problems do not extend to the new problem. We give a linear programming formulation for the bridge problem which is based on the time-expanded network of the original dynamic network.