The shipments of HAZARDOUS MATERIALS (HAZMATs) induce various risks to the road network. Today, one of the major considerations of TRANSPORTATION system managers is HAZMATs shipments, due to the increasing demand of these goods (because it is more used in industry, agriculture, medicine, etc.), and the rising number of incidents that are associated to HAZARDOUS MATERIALS.This paper presents a tool for HAZMATs TRANSPORTATION authorities and planners that would reduce the risk of the road network by identifying safe and economic routes for HM transshipment. Using the proposed linear integer programming model, the HM management system could determine an optimal assignment for all origin-destination pairs for various HAZARDOUS MATERIALS in a TRANSPORTATION network and so reduce the vulnerability due to HAZMATs releases such as population and environmental vulnerability. The model is implemented and evaluated for the HAZARDOUS MATERIALS routing within Fars, Yazd, Isfahan, and Chaharmaha-o-Bakhtiyari provinces of Iran. The branch and- bound algorithm is applied to solve the model using the Lingo software package.