A faulty track circuit has emerged as a prime suspect in the search for clues following the June 22 collision of two Washington, DC, Metrorail trains that killed nine people and injured approximately 80 others.

The circuit, which is part of an automated signaling system that regulates train speed and location, malfunctioned during post-crash tests by National Transportation Safety Board (NTSB) investigators. The results have bolstered speculation that the circuit provided inaccurate information to the moving train’s on-board systems, causing it to crash into the rear of train that had stopped outside the Fort Totten station. 

Metrorail trains are being operated manually while the Washington Metropolitan Area Transit Agency (WMATA), which operates the system, inspects all 3,000 track circuits in its 106-mile rail network. Meanwhile, other transit agencies that use similarly automated control technology for trains and subways are working overtime to assure passengers of their systems’ safety.

This is not the first time track circuit components have caused headaches for WMATA. In 1999, several relays were discovered to be malfunctioning well short of their intended design life. WMATA spent $8 million to replace all 20,000 units. 

Even if the NTSB’s 12- to 18-month investigation pinpoints the faulty circuit as the cause, it’s hard to shake the feeling that the crash was more the result of all the wrong things happening at the wrong time.

For example, there’s role of the moving train’s relatively inexperienced operator, who died in the crash. Evidence shows that she did manually activate emergency brakes at least several hundred feet before reaching the stationary train. But it’s not known whether she had been distracted, as was the case with recent transit incidents in Boston and California, or if the curved stretch of track might have impaired her view. WMATA insists that nothing found so far suggests any kind of operator error.

Then there are the 35-year-old Rohr 1000 Series rail cars, among the oldest in the Metrorail fleet that made up the six-car moving train.

Like the proverbial “bad penny” that keeps turning up, the 1000 Series cars have figured in nearly every major incident on the Metrorail system. Following a 2004 collision that caused only about 20 injuries, but was similar in many respects to last week’s incident, the NTSB recommended the cars be either phased out or retrofitted. Compounding the 1000 Series’ inherent age and reliability issues was the revelation the day after the crash that the lead car in the moving train was two months overdue for scheduled brake service.

Metrorail’s rolling stock includes just under 300 1000 Series cars, and WMATA vows to eventually phase them all out, but the cost will likely approach $1 billion. Finding the cause of the crash will likely be easier than finding those funds, as WMATA lacks a dedicated revenue source from the three jurisdictions it serves—Maryland, Virginia, and the District of Columbia. And even if the funds were available, WMATA estimates it’d be five years before the last 1000 Series car could be taken out of service.

(This week, WMATA announced plans to reconfigure trains so that the remaining 1000 Series cars are “sandwiched” between newer, presumably more reliable cars.)

The agency has also stated that making all the necessary upgrades to its infrastructure, stations, and rolling stock will require $12 billion over the next 10 years, and argues that the federal government should contribute more to the system, given how many of its workers use it to get to work. Congress responded last year with a $1.5 billion allocation with the provision that the three jurisdictions match the amount—a requirement has only recently been met. 

Getting two states and the District to up their contributions to WMATA’s coffers would be a hard sell even in the best of economic times. The transportation funding standoff in Virginia is about to go through its second gubernatorial administration with no resolution in sight. And Northern Virginia voters soundly rejected a 2002 sales tax increase that would have helped ease the region’s perpetually clogged roadways.

So…suspect signaling systems, aging rail cars with a dubious performance history, potential (though unproven) operator errors, maintenance issues, a chronic shortage of money, and a political environment where tax is a four-letter word. Sounds like a recipe for the worst kind of disaster of all—one where all the danger signs are clearly evident, yet are overlooked or even ignored, until it’s too late.