Route determination for hazardous material (Hazmat for short) transportation is a main concern in Hazmat management in which transport risk and cost are considered as the main attributes. The pre-defined priorities for risk and cost cause different mathematical models developed to determine the best routes which are not necessarily the shortest paths. In this paper, a tolerated risk usage is utilized to develop mathematical model for selecting the best route for carrying hazardous materials according to risk and path distance. Mathematical model has been developed using preemptive goal programming approach in which transport risk is considered more important than distance at the first step for developing model and route distance is minimized subject to pre-defined risk tolerance at the second stage. Experimental data including 89 nodes and 101 links in a real network has been selected for numerical analysis and results have been discussed. Results revealed that there are some alternative routes when risk tolerance is getting to be increased or long distance paths used for hazardous materials transportation. In addition, using tolerated risk can satisfy both national/local authorities in hazmat management and transport companies as well.