Elec­tri­cal-leak test­ing could re­duce Metro melt­downs, but it’s not a fast fix

The Washington Post Sunday - - COMMUTER - BY MAR­TINE POW­ERS mar­tine.pow­ers@wash­post.com

As smoke and “arc­ing” is­sues con­tinue to plague Metro, agency of­fi­cials say re­lief may be in sight: a pre­ven­tive main­te­nance pro­gram start­ing in July that will al­low work­ers to be­gin test­ing for elec­tri­cal leaks along the sys­tem’s power ca­bles and tracks.

But there’s one prob­lem: The test­ing process is slow, cum­ber­some and time in­ten­sive — and it will prob­a­bly be a while be­fore rid­ers start notic­ing re­sults.

“What we’re striv­ing for is a sus­tain­able so­lu­tion,” said SafeTrack di­rec­tor Laura Ma­son. “There’s no quick fix to prob­lems that can take years to evolve.”

Elec­tri­cal events are a re­cur­ring prob­lem on the tran­sit sys­tem, ev­i­denced by the most re­cent se­ries of prob­lems with smol­der­ing stud bolts near the heart of the Red Line. One of those events re­sulted in an hours­long shut­down near Metro Cen­ter last month that some rid­ers called the worst Metro com­mute of their lives.

The elec­tri­cal prob­lems come in two main forms. The first is cable in­su­la­tion: The cop­per ca­bles that run elec­tric­ity from power sub­sta­tions to the third rail are sup­posed to be cov­ered in a thick layer of in­su­la­tion. Some of those ca­bles are 40 years old, and in­su­la­tion is be­gin­ning to wear thin in spots. Many of those ca­bles need to be re­placed — but with hun­dreds of miles of cable, it’s hard to know which to pri­or­i­tize.

The other prob­lem oc­curs on the op­po­site side of the tracks from the third rail — where elec­tric­ity that pow­ers the train’s propul­sion sys­tem leaves the train through its metal wheels and trav­els back to­ward the power sub­sta­tion. The elec­tric­ity is sup­posed to travel straight from the run­ning rail that sup­ports the wheels, into an­other set of ca­bles and back into the power sys­tem.

But there are plenty of other metal com­po­nents that sta­bi­lize the rails and af­fix the tracks to the ground. Those com­po­nents are sup­posed to be in­su­lated with rub­ber gas­kets so they can’t be elec­tri­fied. But the in­su­la­tion on those com­po­nents has aged and worn, too. The buildup of wa­ter, dirt, dust or mud can serve as a con­duc­tor. It be­comes easy for those com­po­nents to be­come elec­tri­fied, over­heat and emit sparks or plumes of smoke as the elec­tric­ity trav­els from those com­po­nents into the ground.

In both cases, it’s an is­sue of bad in­su­la­tion and elec­tric­ity trav­el­ing to places where it shouldn’t. And in both cases, those prob­lems are dif­fi­cult to see with the naked eye.

That’s why Metro plans to kick­start two strate­gies to help cut down on those in­ci­dents by de­tect­ing elec­tri­cal leaks be­fore they be­come full-blown arc­ing in­ci­dents or cable fires. The timein­ten­sive process is one of the rea­sons Metro ral­lied so hard to roll back late-night ser­vice and launch the pre­ven­tive main­te­nance pro­gram that is sup­posed to start July 1.

In both pro­cesses — called “cable meg­ger­ing” and “stray cur­rent test­ing” — tech­ni­cians must first iso­late in­di­vid­ual sec­tions of the track or the power ca­bles. They have to turn off power to the tracks, and it’s not as sim­ple as flip­ping a switch. Work­ers don pro­tec­tive out­fits that look like space­suits and pull out gi­ant break­ers from the power sub­sta­tions that sur­round the tar­geted sec­tion of the tracks. It’s a process that can take more than an hour.

Work­ers then in­ject the ca­bles or the third rail with elec­tric­ity, mea­sure the volt­age and check for ab­nor­mal­i­ties that could in­di­cate elec­tric­ity is leak­ing.

But that’s the easy part. If the tests in­di­cate that elec­tri­cal cur­rent might be stray­ing from its in­tended cir­cuit, work­ers have to track down the source of the leak. And that can take a while.

Ma­son out­lined the math­e­mat­i­cal chal­lenge of the en­deavor: There are about 80 metal fas­ten­ers per 100 feet of track. The stretch of tracks that might be tested at one time is a cou­ple thou­sand feet. That’s 1,600 fas­ten­ers to check — and it takes just one poorly in­su­lated fas­tener to re­sult in a smoke emis­sion that could ruin a com­mute for tens of thou­sands of rid­ers.

“You quickly in­crease the num­ber of com­po­nents that you’re check­ing and mea­sur­ing,” Ma­son said. Ul­ti­mately, she said, Metro’s goal is to get to a place where ev­ery stretch of the tracks gets tested for stray cur­rent once ev­ery four years, though more prob­lem­atic sec­tions of the sys­tem prob­a­bly would re­ceive more fre­quent treat­ment.

That’s also why stray cur­rent test­ing and cable meg­ger­ing were not per­formed fre­quently dur­ing SafeTrack. You can’t do the tests while you’re per­form­ing other re­pair work on the tracks. Metro of­fi­cials thought that other work should take pri­or­ity, rather than us­ing up golden pe­ri­ods of round-the-clock un­in­ter­rupted track time to per­form elec­tric­ity tests.

It can take as long as three nights of test­ing to determine the source of stray cur­rent in one rel­a­tively short seg­ment of the tracks. And even then, it’s not clear whether the de­fect that caused the elec­tric­ity to bleed to the track com­po­nents is ac­tu­ally a prob­lem that would ever have caused a full-blown arc­ing in­ci­dent.

Metro used to have a meg­ger­ing pro­gram, though it was sus­pended years ago. Be­fore the agency de­cided to re­vive the pro­to­col, staff sent a sur­vey to seven other tran­sit agen­cies to learn about whether, and how of­ten, they test for leak­ing ca­bles, said Mike Hass, Metro’s gen­eral su­per­in­ten­dent of trac­tion power main­te­nance. The re­sults var­ied: Some tested con­stantly, others only used the process in re­sponse to a spe­cific prob­lem. Sev­eral ma­jor tran­sit agen­cies had beefed up their elec­tri­cal-leak test­ing pro­grams only in the past cou­ple of years.

It turns out that meg­ger­ing and stray cur­rent test­ing is of­ten scrimped on at other tran­sit agen­cies for the same rea­son the re­sults aren’t im­me­di­ate: It’s a long process, and you spend a bunch of time hunt­ing down a de­fect that might never re­sult in a prob­lem for pas­sen­gers.

“It’s like play­ing whack-a-mole a lit­tle bit,” said Randy Clarke, vice president of op­er­a­tions and mem­ber ser­vices at the Amer­i­can Pub­lic Trans­porta­tion As­so­ci­a­tion. “You’ve got to keep do­ing all this work to find some­thing that may or may not be a big prob­lem for you.”

And be­cause the test­ing can only happen at night — power must be shut off to both sides of the tracks, so no sin­gle-track­ing — work­ers only have one or two hours each night to test those in­di­vid­ual com­po­nents be­fore they must get off the tracks, re­con­nect the power and al­low morn­ing ser­vice to re­sume.

“WMATA is not alone in this,” Clarke said. “You can be chas­ing some­thing that only hap­pens ran­domly. Even though you might think it’s fixed, the prob­lem reap­pears. It’s time con­sum­ing and can be frus­trat­ing.”

Newspapers in English

Newspapers from USA

© PressReader. All rights reserved.