Spatial externalities and optimal locations – simulations on a theoretical network

Simulations are performed on a squared lattice of 325 points in order to test the sensitivity of the solutions suggested by a standard location-allocation model (an extension of the p-median) to the introduction of spatial externalities. Negative externalities are considered; they are here supposed to decrease linearly with distance from the pollution source and to be additive to transportation costs borne by the consumers. Outputs of the model are systematically discussed. Maps show the systematic changes of the optimal locations with the intensity and/or the extension of the pollution. This exploratory paper leads to interesting conclusions in regional economics and land planning, and opens up a broad avenue for further investigations.