Optimization of Rail Defect Inspection Frequency to Reduce Railroad Hazardous Materials Transportation Risk Liu, X., C.T. Dick, M.R. Saat and C.P.L. Barkan. 2014. Optimization of Rail Defect Inspection Frequency to Reduce Railroad Hazardous Materials Transportation Risk. In: Proceedings of Transportation Research Board 93rd Annual Conference. Washington, DC. Files Optimization of Rail Defect Inspection Frequency to Reduce Railroad Hazardous Materials Transportation Risk - Full Text (PDF) Categories Safety and Risk