In this paper, a bi-objective mathematical model for emergency services location-allocation
problem on a tree network considering maximum distance constraint is presented. The first
objective function called centdian is a weighted mean of a minisum and a minimax criterion
and the second one is a maximal covering criterion. For the solution of the bi-objective
optimization problem, the problem is split in two sub problems: the selection of the best set of
locations, and a demand assignment problem to evaluate each selection of locations. We
propose a heuristic algorithm to characterize the efficient location point set on the network.
Finally, some numerical examples are presented to illustrate the effectiveness of the proposed
algorithm.