Fort Totten Metro Crash Investigation Reveals Rush-Hour Problems

In the painstaking NTSB investigation of the June 22nd Fort Totten Metro crash some interesting findings are coming to light. The focus has been on so-called impedance bonds in the area of the crash, one of which was replaced five days before. The bond on the other end of the circuit was replaced in December 2007 and has been fluctuating ever since.

What does this mean in practical terms? It means first of all that some indication of problems has been around for eighteen months. Metro is a highly complex system and it is not clear whether either train operators or other Metro employees had complained about these circuit problems.

It also appears that the fluctuations increase during rush-hour travel. Obviously that is not good news and the origin of these problems is being looked at closely. The N.T.S.B. has suggested that possible sources of problems include electromagnetic interference, traction power harmonics, and possibly communications related interference. Whatever the cause, it is inhibiting the automatic train control system and must be cured.