Key Findings

• OBRDS detected 27 out of 28 rail breaks during the 2025 FAST performance evaluation. This corresponds to Probability of True Positive of 0.96.
• OBRDS produced one False Negative (undetected broken rail) and zero False Positives.
• OBRDS detected FAST rail breaks on a tie plate, in a turnout/dead zone, on a barred defective rail, and in rail ends still touching after the break. These were not detected by track signaling systems.
• OBRDS requires information on all pre-existing or known features, such as insulated joints, in the track being monitored.
• OBRDS requires maintaining the rail sensor height at 15 mm from rail running surface. The test car was tested through the partial flange bearing frog for sensor clearance and passed because it did not pose any clearance issues.
• The OBRDS positioning in the train does not impact rail break detection effectiveness. In all cases, the timing does not provide an opportunity for protection of the host train consist. OBRDS positioning at the end of the train does provide additional protection for the following train by detecting breaks that occur during the passage of the host train.