comparison between combined and separate approaches for solving a location-routing problem in hazardous materials transportation

in the case of hazardous materials management, selected routes for carrying hazardous materials (i.e.,hazmat) have significant effects on locating hazmat distribution centers. since, risk and cost are usuallyconsidered as two main attributes to determine the best routes, optimized locations are sequentially outlineddepending on selected routes. in the present paper, two different approaches of developing separate andcombined models of routing and locating problems have been utilized to determine hazmat transport routestogether with optimized locations for distribution centers. while mathematical models are developed to carryout the above concepts, a three-stage procedure has also been developed to determine the routes and hazmatquantities should be required to transport for each origin destination pairs. an experimental network consistsof eighty-nine nodes and one hundred and one links has been used as case study for analytical process andmodel validation. results revealed that, although two different models have been developed following theabove approaches, but results are the same. therefore, decision makers who are dealing with hazardousmaterial management should not be worried about the approach which is better to be utilized for solvingrouting-locating problem.