Analysis of Freight Train Derailment Rates for Unit Trains and Manifest Trains

Freight rail is a safe and efficient mode of transporting hazardous materials. Railroad hazmat transportation safety is a high priority for the industry, academia, and government. In the past decade, the revenue ton-miles and car-miles of hazardous materials transported by unit trains have significantly increased in the United States. An understanding of the safety aspects of unit trains, in particular for hazmat unit trains, can contribute to the identification and evaluation of practical hazmat accident prevention strategies. However, limited prior research has focused on unit train derailment risk analysis. As part of this effort, this paper develops a quantitative analysis of freight unit train derailment characteristics and derailment rates for unit trains and manifest trains (mixed trains). The freight train derailment data on Class I railroad mainlines between 1996 and 2018 were analyzed by specific train types, including hazmat unit trains, non-hazmat unit trains and manifest trains. The derailment rates measured by three traffic exposure metrics, which are train-miles, ton-miles, and car-miles, are estimated and compared. The analyses show that a unit train has a 30% lower rate per billion ton-miles and per billion car-miles than manifest trains. Loaded unit trains have roughly four-fold derailment rate (in terms of derailments per million train-miles or per billion car-miles) of that of empty unit trains. Within loaded unit trains, hazmat unit trains have lower derailment rates than non-hazmat unit trains. Overall, heavier and shorter loaded unit trains tend to have greater derailment rates per billion ton-miles and per billion car-miles.


  • English

Media Info

  • Media Type: Digital/other
  • Features: References; Tables;
  • Pagination: 18p

Subject/Index Terms

Filing Info

  • Accession Number: 01763620
  • Record Type: Publication
  • Report/Paper Numbers: TRBAM-21-03709
  • Files: TRIS, TRB, ATRI
  • Created Date: Dec 23 2020 11:07AM