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Operations Research Models and Methods
Problems Section
Network Flow Programming Models
 - Ambulance Routing with Fixed Charges

The figure below shows a network of one-way streets. An ambulance station is located at intersection A. The monthly demands for ambulance service at the intersections are shown in the square brackets adjacent to the nodes. There are two costs associated with each street as shown in the parentheses adjacent to the arcs. The first number is the cost of installing special communications equipment that control the street lights. This is a fixed cost per month that is expended if the street is selected for a route. It is independent of the number of times the street is used. The second number on an arc is the unit cost of a trip down the street.

We want a mathematical programming formulation whose solution will determine the minimum cost selection of streets that will serve all the intersections shown. Use a network model with additional variables defined to represent the fixed charges.

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Operations Research Models and Methods
by Paul A. Jensen
Copyright 2001 - All rights reserved