During Wednesday’s system closure, Metro’s work crews found at least 26 power cables and connectors that required immediate repair. This makes you wonder: What will it take to uncover similar issues?
The Metrorail system shut down for the whole day Wednesday so that track crews could inspect and repair all 600 train power cables. General Manager Paul Wiedefeld said the system was divvied up into 22 sections and crews went to work checking them all, repairing the ones which were found to be in unacceptable condition.
By the agency’s 6 pm press conference on Wednesday, Metro had inspected 80 percent of the cables and found that 26 required repairs. It had fixed 18, and it handled the rest overnight, before today’s opening.
"Let me tell you, the shut down today was necessary” said Wiedefeld. While there weren’t any cables in immediate danger of causing a fire, Wiedefeld said enough were in a “hazardous condition that we cannot accept” to justify stopping all trains for a day, a very rare move in Metro’s 39-year history.
Third rail power jumper cable “boots.” The third rail is under the white cover that follows next to the track. Image from WMATA.
Here’s the issue
The power cables that were called into question after the fire on Monday are part of the third rail system, which powers trains so they can move down the track. The “jumpers” as they’re called are used to bridge gaps in the third rail, like when the third rail has to move from one side of the track to the other. The jumper cables allow the third rail to be on whichever side of the track it needs to be on to create a continuous supply of power for the trains passing on the track.
According to Wiedefeld and Board Chairman Jack Evans, the Monday fire was similar to the one at L’Enfant Plaza in January of 2015. At L’Enfant, a defective power cable missing some of its insulation, which would prevent moisture and dirt from getting into the cable, made contact with another piece of metal, like the tunnel wall. This caused sparking which led to fire and smoke, and in essence is a common form of a power “short” — where the path of the electrons deviates from where you want them to go — just on a larger scale and with more dire consequences.
After the L’Enfant fire and death of a passenger, WMATA re-inspected all of these power cables. WMATA replaced 125 cables, and inspections were set up for the cables to be inspected yearly.
Wiedefeld didn’t say if any of the 26 cables found Wednesday had been replaced last year, so we don’t know if the cables are just one year old and failed recently, or if the issues were missed during routine inspections. The power system is one of several in Metrorail that, if it isn’t working nearly perfectly, could harm employees, emergency personnel, or passengers.
The NTSB recommended WMATA replace all faulty cables last year
The NTSB issued a press release and recommendation to WMATA saying that issues with some of the power connections required “immediate action.” The agency found that some jumper cable boots supplying power to the third rail weren’t installed with proper insulation, meaning that water and debris could reach the metal carrying the power and cause a short or spark.
In addition the evidence collected at L’Enfant, the NTSB also pointed to the electrical “smoke event” in the tunnel outside Court House as being caused in part due to faulty power cable installation.
"Investigators found that cable connectors were missing ‘sealing sleeves’ designed to keep moisture and contaminants away from the high-voltage conductors,” read the NTSB report.
The NTSB’s immediate action recommendation instructed Metro to inspect and verify that all cables that were installed had been properly constructed, which the inspections and repair in June were said to have accomplished.
The FTA questioned the thoroughness of WMATA track inspections
The Federal Transit Administration issued a scathing 116-page report last summer detailing numerous safety issues that their inspectors found when investigating how WMATA does business.
One of the issues listed in the report is one that claims that the number of people available to do track inspections was cut in half, meaning that each group of two track walkers meant to inspect the rail and nearby equipment includes only one person who is actually inspecting the tracks, fasteners, power equipment, and electrical systems. The other worker, who used to check the tracks as well, is now dedicated to looking out for trains, which could be coming at any time.
The FTA heard from track inspectors themselves who said that they “cannot adequately inspect both running rails and the third rail” in the time they have to get the inspections done. A side-effect of this could be that the track personnel skip or gloss over more subtle issues, letting them fester until turning into a full-blown issue.
What else is lurking in the tunnels?
With the discovery this week of a system-wide issue with faulty power cables, one has to wonder what might be next. The system inspection in September of Metro’s tracks, which only came in response to the derailment at Smithsonian station, revealed several missed code-black defects which should have been caught but weren’t. With the seemingly long-held attitude of reacting to problems at Metro instead of getting out in front of them, it’s very possible there’s another incident just waiting to happen.
Lets hope Mr. Wiedefeld and crew squash the festering problems before they show themselves again.