Cost-effectiveness of reducing environmental risk from railroad tank car transportation of hazardous materials

Research on hazardous materials transportation safety and risk has traditionally focused on acute hazards to human health and property. This research, sponsored by the Association of American Railroads (AAR), describes the first transportation risk analysis to consider the potential impact on the environment. The environmental risk from transportation of 24 of the chemicals most commonly shipped in railroad tank cars was calculated and the cost-effectiveness of using more damage-resistant tank car designs evaluated. Of particular interest was the impact on soil and groundwater.; A quantitative risk assessment (QRA) model was used to conduct consequence analysis in terms of remediation cost for spills of each chemical. Exposure analysis involved use of geographic information system (GIS) software to conduct a probabilistic assessment of the occurrence of 15 environmental scenarios (three soil types x five ranges of groundwater depth) near railway lines. These results were combined with the probability distribution of spill quantities for each tank car type, commodity, environmental scenario, and remediation cost, and several metrics of clean-up-cost risk were developed. The risk per car-mile for the different chemicals ranged from 0.11 to 29.10 cents.; DOT 111A100W1 specification tank cars are the most commonly used cars for the commodities considered. A variety of alternative tank cars with more protective features such as, half- or full-height head shields, jacket and insulation and top fittings protection were considered. Although the alternate cars are safer, they are also heavier and more expensive to build and operate. Cost-benefit analysis was conducted to determine if the reduction in the risk offset the extra cost of the more robust car. Three replacement schedules were considered: attrition-based, immediate, and a 10-year retrofit schedule. Under attrition-based replacement, all the commodities yielded a positive Net Present Value (NPV) for the enhanced safety 286,000 pound (286K) gross rail load (GRL) 111 tank car. This tank car was unique because it improved safety and reduced operating cost relative to the 263K alternatives. There were a few cost-beneficial 263K alternatives but the enhanced 286K 111 car yielded the largest NPVs.