Technical Reports

BNSF San Bernardino Case Study: Positive Train Control Risk Assessment

  • 30
  • Sep
  • 2014
AUTHOR: Daniel Brod and Boaz Leslau
SUBJECT: Positive Train Control, Signal and Train Control, Risk Assessment
KEYWORDS: Positive Train Control, Generalized Train Movement Simulator, I-ETMS, risk assessment, level splitting, engineering reliability metrics
ABSTRACT: The Federal Railroad Administration funded the BNSF San Bernardino Case Study to verify its Generalized Train Movement Simulator (GTMS) risk assessment capabilities on a planned implementation of the I-ETMS PTC system. The analysis explicitly simulated a 10-year period of railroad operations. During simulation, all initiating errors and failures of PTC-preventable accidents were captured and stored along with the entire system state. Subsequent analysis conducted repeated simulations based on random draws from these stored initiating system states to generate hazards and accidents with equivalent statistical confidence of more than 300 years of conventional Monte Carlo simulation. Subject to model assumptions, Base Case mean time to accident (MTTA) for collisions by type is: head-head 4.5 years, head-tail 11.8 years, and sideswipe 2.56 years. An over-speed derailment accident is predicted with a frequency of once every 8.6 years; risk of work zone accident is negligible. As modeled, I-ETMS mitigates all but negligible risk of PTC-preventable accidents with a high degree of confidence. A sensitivity analysis confirms these results. Changes to operating assumptions that could indicate greater risk in the Base Case actually show small variance in total risk. However, there is greater variance in the mix of accidents by accident type.