The flow capturing and the p-median location-allocation models deal quite differently with demand for service in a network. The p-median model assumes that demand is expressed at nodes and locates facilities to minimize the total distance between such demand nodes and the nearest facility. The flow-capturing model assumes that demand is expressed on links and locates facilities to maximize the one-time exposure of such traffic to facilities. Demand in a network is often of both types: it is expressed by passing flows and by consumers centred in residential areas, aggregated as nodes. The authors here present a hybrid model with the dual objective of serving both types of demand. They use this model to examine the tradeoff between serving the two types of demand in a small test network using synthetic demand data. A major result is the counter-intuitive finding that the p-median model is more susceptible to impairment by the flow capturing objective than is the flow capturing model to the p-median objective. The results encourage the authors to apply the model to a real-world network using actual traffic data.
