As fuel costs and environmental impacts assume greater importance to railways, so does the importance of options for increased energy efficiency and emissions reduction. A study was conducted on the potential recovery of dynamic brake energy from diesel-electric locomotives in North American freight service. Using computer simulations (Train Energy Model) and locomotive event recorder data, estimations were made of the energy that could be recovered from dynamic brake use. In addition, the differences between the results of the computer simulations with respect to the actual events recorded were examined in order to evaluate how well the model simulates an engineer's operation of locomotives and provide guidance for future improvements to the simulation model. A case study of the energy recovery potential for a Class 1 railroad operating on a major mountain pass in North America was conducted. The route analyzed has two characteristics that make it a good candidate for studying energy recovery potential. First, there is an extended down grade approximately 25 miles long, and second, it has heavy traffic with about 80 trains a day traversing it. Both of these factors enhance the likelihood that investment in energy recovery technology will be economically viable. It was found that the total dynamic brake energy potential was over 1,200 kilowatt-hours per train. Depending on the efficiency of the storage system, as much as 70 gallons of diesel fuel could be saved per train. This equates to 2,800 gallons of fuel a day and a corresponding reduction in emissions. Never the less, fuel savings themselves do not provide enough incentive to warrant implementation of dynamic brake energy recovery, but with the addition of environmental cost savings financial benefits may be seen.