Why didn Metro do something about the track circuit that was intermittently failing between June 17 and 22?
Repair work was done on this circuit on June 17 and was tested to ensure that it was working properly. At the time it was tested, all indications were that the circuit was working properly. Since the accident, Metro has increased the frequency of its track circuit data review from once every 30 days to twice daily (14 times per week) and is doing a deeper level of analysis with more stringent requirements. Engineers review computerized reports after each rush hour and investigate every anomaly they see. Metro is working with an existing contractor, ARINC, and other outside vendors on developing a real-time monitoring system that would detect circuit failures and generate alerts.
