by jkovach
NTSB wrote: 10. Train operators did not report problems with track circuit B2-304 before the accident because reductions in speed commands to maintain train separation, or even momentary losses of all speed commands, were common during train operations.I think this may still be happening. You can see the cab signal speed display from the "railfan seat" in the front of the car, and I've been on several trains where the allowed speed periodically dropped to 0 for a second or two (causing the overspeed alarm to go off and the operator to apply the brakes) and then went back to whatever it was showing before.
NTSB wrote: To Washington Metropolitan Area Transit Authority:This certainly makes it sound like GRS has a design defect in their product. Should be "interesting" to watch this one play out.
6. Because of the susceptibility to pulse-type parasitic oscillation that can cause a loss of train detection by the Generation 2 GRS audio frequency track circuit modules, establish a program to permanently remove from service all of these modules within the Metrorail system.
Undoubtedly in the aftermath of this accident and investigation there will be a lot of new rules passed (and hopefully new money provided to assist with compliance), causing Metro to clean house, replace the defective equipment, improve their monitoring systems, and the like. This will almost certainly result in improved safety on the system in the near to medium term. But ten or fifteen years down the line, will complacency set in and history begin to repeat itself? That is the $64,000 question...
Looking forward to reading the full report.