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Bug Transportation

What's Frying the Electrical Systems On BART Trains? (ieee.org) 250

Tekla Perry writes: Earlier this month, BART engineers shut down a substation in hopes that the closure would quiet the power surges that were frying the electrical propulsion equipment on BART cars -- a peak of 40 in just one day in February. The shutdown seemed to solve the problem, but BART officials weren't sure they'd really found the answer. Yesterday, the power surges popped up again, on an entirely different section of tracks, damaging 50 cars before BART closed off that section, rerouting passengers onto buses. Track inspections yesterday revealed nothing, and BART reports that it has reached out to experts around the country and asked them to fly in and help solve the mystery. Do you have a theory? Note: BART is the 5th-busiest heavy-rail rapid transit system in the U.S.
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What's Frying the Electrical Systems On BART Trains?

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  • by fragMasterFlash ( 989911 ) on Thursday March 17, 2016 @09:35PM (#51719553)
    Which nation-state is sponsoring the hacking crew that will inevitably be blamed for this issue?
  • I-squared-L? (Score:5, Interesting)

    by swschrad ( 312009 ) on Thursday March 17, 2016 @09:41PM (#51719585) Homepage Journal

    could there perhaps be enough inductance in the multi-motor systems that it is generating its own connect/disconnect/connect surges? try isolating those DC motor controllers from both the track and the motors with some diode stacks and snubber caps.

    • Oh come on. It couldn't possibly be that simple. I write software for a living and even I know to look for back emf first.

      • Nine out of ten times the solution is the "oh c'mon, they can't be THAT dumb!" one.

        • by hey! ( 33014 ) on Friday March 18, 2016 @08:55AM (#51722087) Homepage Journal

          I had a boss once who hired a consultant and was angry when the consultant told him to do the obvious thing.

          "You know what a consultant is?" he groused. "Someone who borrows your watch to tell you the time."

          I thought about this for a moment. "Yeah, but what's he supposed to do if you're standing there with the watch on your wrist and you don't know what time it is?"

        • by Aaden42 ( 198257 )

          And eleven out of ten times, they are in fact THAT dumb.

          (And the other time it's an off-by-one erro

      • Re: I-squared-L? (Score:4, Informative)

        by geoskd ( 321194 ) on Friday March 18, 2016 @06:11PM (#51727515)

        Oh come on. It couldn't possibly be that simple. I write software for a living and even I know to look for back emf first.

        True, but as the article mentioned, the system was designed for 1/20th of the current passenger load. I suspect that the problem actually lies in the way these cars are slowed. The obvious (intelligent) way to do it would be to induce back emf into the supply, and put some of the energy back into the system in the form of increased mains voltage. In small amounts (one car at a time), this would be a relative non-issue. In larger amounts, an especially unlucky synchronization of cars all slowing simultaneously could, in theory, overload the system and cause massive transients.

        The articles also mention that the cars have both DC and AC motors, but only the DC motors are getting cooked. This leads me to expect that the problem has been building up for a while, but has been below the threshold of damage to the motors until recently. The fact that it is the thyristors (used to rectify the AC power for DC use) which are failing, tells me that both the AC motors and the DC motors have been receiving severe overloads, but the Thyristor was simply the weakest component and has been failing first.

        If it turns out that the back emf is the culprit, the solutions are not simple. In effect, they need to find somewhere for that energy to go other than back into the supply network. Any option they go with is either going to A) significantly reduce the efficiency of the system or B) require additional expensive hardware be installed onto every car.

    • Re:I-squared-L? (Score:5, Insightful)

      by Archfeld ( 6757 ) <treboreel@live.com> on Thursday March 17, 2016 @11:32PM (#51720007) Journal

      Unless they have recently upgraded a mass of cars or track, why does it suddenly start happening now ? The system has been in use and fairly reliable for a long time. I have no proof, but the suspicious borderline paranoid inside me is screaming that someone is hacking at the electrical infrastructure that feeds the Bart system, and the problem lies outside their direct observation, and is likely with PG&E's supply system to Bart. PG&E has demonstrated the disregard for maintenance, monitoring, and the security incompetence in the last few years to allow for something like this. It will likely take some outside support for Bart to prove the failures don't lie inside their infrastructure to get PG&E to even begin to look at their own systems.

      • by MrDoh! ( 71235 )
        Hacking sounds solid. To eliminate other things; Physical check of the power along the entire route, see if someone's tapped it for any reason or there's 'odd boxes' attached to junctions/controllers?
    • Couple that with time and mechanical wear.. The bionding between rail segments is wearing out, (and/or being stolen for scrap metal value.) A few intermittant rail to rail connections based on rail movement, (as when a fully loaded train passes over), would inflict a world of hurt on the 1000volt DC electronics.

      • Re:I-squared-L? (Score:4, Interesting)

        by BronsCon ( 927697 ) <social@bronstrup.com> on Friday March 18, 2016 @02:10PM (#51725645) Journal
        On one hand, if the (looks like 000 gauge) conductors connecting the rails are being stolen, that could post a problem. On the other hand, since there are 4 paddles on each side of each car (as the 3rd rail can be on either side, depending on which side the platform is on at the next station), each car maintains contact with both rails as it transitions from one to the next. Likewise for the wheels, making the ground connection for each car. Coupled with the fact that cars share power, a 10 car train will be in contact with 4 or 5 rail pairs at any given moment, a majority of the bonding conductors would have to be missing or severely damaged to cause even a minor power issue. Cars are sized such that when the front of the train is crossing a rail threshold, the rear of the train is in the middle of a rail, so good contact is guaranteed at all times unless the first or last car is severely damaged and missing at least two paddles on the 3rd rail side. Even then, the likelihood of damage is minuscule.

        It is almost certainly a supply problem.
  • by hawguy ( 1600213 ) on Thursday March 17, 2016 @09:45PM (#51719607)

    BART already tweeted the reason [nytimes.com] behind the breakdowns:

    From @SFBART:
    BART was built to transport far fewer people, and much of our system has reached the end of its useful life. This is our reality.

    BART has been continually expanding while deferring maintenance on the rest of the system, and that policy has finally come home to roost -- much of their infrastructure is over 40 years old and they can't defer maintenance forever. But by continually expanding, they've made themselves too big to fail (and they've gotten more counties on the hook to keep the service running), so they'll get bailed out one way or another.

    • I don't buy that one for a second, it makes way too much sense. I think it's people urinating on the 3rd rail, and we need another season of Mythbusters to prove it!

    • But by continually expanding

      The number of people a transit system serves is determined by the choices of those people, not the administrators of the system.

      • by Dahamma ( 304068 )

        But by continually expanding

        The number of people a transit system serves is determined by the choices of those people, not the administrators of the system.

        It's obviously both, but in this case THEIR wording does refer to the administrators since by "expanding" they mean "adding additional stops". Kind of a "duh" comment, really...

      • by hey! ( 33014 )

        That's a bit simplistic. If you expand a system, it will automatically attract more riders if the cost to the rider remains the same. And therein lay the rub. The rational basis of the decision to expand the system is a cost/benefit one, even if the system is publicly subsidized. The rationale for public subsidies is based on there being market externalities, but once you factor in those externalities the benefits have to outweigh the costs.

        That's where politics comes in. Service expansion is popular, b

    • by bill_mcgonigle ( 4333 ) * on Thursday March 17, 2016 @10:17PM (#51719749) Homepage Journal

      BART already tweeted the reason [nytimes.com] behind the breakdowns:

      That's not a reason - it's a complaint (and a beg for more money). Maybe they do need more money, but if the cause of the surges remains a mystery, then by definition they don't know the reason.

      I'm sure they don't have any SCADA systems exposed to the Internet (right?), but "old stuff" is just a guess. And there are some good "old stuff" guesses elsewhere on this story.

    • ...when all their money is going to high salaries and benefits for union employees [mercurynews.com]?

      Over 200 BART employees earned over $200,000 a year in total compensation...

    • by DarkSabreLord ( 1067044 ) on Friday March 18, 2016 @02:35AM (#51720579)

      It's not just that - BART was simply never meant to be operating on the scale it does today. When BART was built, the creators envisioned a system that would serve about 100,000 people per week and choke points such as the Transbay Tube were built accordingly. Naturally, as the population increased, upgrades had to made. This worked for a while, but eventually lack of funding for serious overhauls caught up with the
      constantly increasing ridership [imgur.com]. Maximum capacity is heavily influenced by the fact that sections like the tube are single line, with no easy way to expand to double or triple. BART could theoretically be a 24/7 system, but as things stand now their engineers need every minute of the nightly downtime they have to service a rapidly aging rail system.

      The rails already in place are almost at capacity, with a train crossing over them every 2 minutes. With the tech booms of the last decades, there's been an even bigger spike in these numbers. Over the last decade alone, passenger alightings at some stations have more than doubled. On busy days, the BART system now serves 25 times more riders than originally envisioned. There's some money for additional trains, but that can only do so much. Eventually, we are going to need to spend money on either more parallel tracks, cars, and bigger platforms or just a new system altogether.

      Their administrators are simply being realistic about the situation we're in [vox.com]

    • BART has been continually expanding while deferring maintenance on the rest of the system, and that policy has finally come home to roost -- much of their infrastructure is over 40 years old and they can't defer maintenance forever. But by continually expanding, they've made themselves too big to fail (and they've gotten more counties on the hook to keep the service running), so they'll get bailed out one way or another.

      Bullshit. The substation that was first identified as a problem is a mere months old.

    • A 40 year old electrical system? Oh woes me!

      Seriously though while you may be right electrical systems, especially the always on kind which don't cycle can last for a hell of a long time much longer than 40 years. But there are some peculiarities though. Taking maintenance into account a lot of failures are very overt and instantly show the source of the problem through arcing or flashovers in the piece of failed gear. Typically you know straight away where the source of the problem is, and the simplicity o

    • BART already tweeted the reason [nytimes.com] behind the breakdowns:

      From @SFBART:
      BART was built to transport far fewer people, and much of our system has reached the end of its useful life. This is our reality.

      BART has been continually expanding while deferring maintenance on the rest of the system, and that policy has finally come home to roost -- much of their infrastructure is over 40 years old and they can't defer maintenance forever. But by continually expanding, they've made themselves too big to fail (and they've gotten more counties on the hook to keep the service running), so they'll get bailed out one way or another.

      That's a political answer to justify asking for more money - it is not a technical answer that should be accepted on /.

  • Damn those Chinese capacitors! Damn you to hell!

  • I suspect ... (Score:5, Interesting)

    by PPH ( 736903 ) on Thursday March 17, 2016 @09:51PM (#51719649)

    ... some sort of interaction between filter/power factor capacitors in the new substation and the inductive reactance of the tracks and distribution system. Transients caused by the inherent imperfect third rail to car contacts causes a ringing (oscillation) in the system which, with the new substation on line, happens to be on or near a frequency that some of the rolling stock motor controllers don't like.

    Throw some power quality analyzers on various sections of the track and watch the system's transient voltage response with power sources in various configurations.

    • by 93 Escort Wagon ( 326346 ) on Thursday March 17, 2016 @11:27PM (#51719985)

      Transients caused by the inherent imperfect third rail to car contacts causes a ringing (oscillation) in the system ...

      Oh, sure - blame the homeless.

    • by gopla ( 597381 )

      Seems most probable cause.

      I don't know the technical details of BART systems sitting in India. Is it supplied by 60 Hz AC and the rectifiers are installed on the cars that run on DC motors? Usually these power electronics devices build in 1980s are robust enough. We have gained experience now and toughened the circuit in modern drives, but I doubt it be the case in 80s. Any adverse interaction with filters or may be some kind of ferroresonance can cause high voltage and damage such equipment.

      Throw some po

  • by Anonymous Coward on Thursday March 17, 2016 @10:01PM (#51719687)

    So the A & B cars having inductions motors seem to be fine, while the problem seems to be confined to the C cars having the DC motor. That's one difference.

    Also, what else has changed? Take a look at wunderground to see that the Bay Area is having a wet season.

    Why would the C cars have been mostly fine all along and having trouble now?

    So there's charge building up in the DC motors that they can't handle and that makes them blow out. The charge has nowhere to go. What controls the flow of charge? Grounding. What can go wrong with grounding? Good grounds can go bad when a lot of discharge causes the sand in the soil to vitrify (melt into glass) after discharges and lightning strikes have been shooting through it for decades. Better grounds can unexpectedly form when more highly conductive paths form up. The AC induction motors will suffer a power loss but can handle the charge jumping back & forth in unexpected ways, while the DC motors can't.

    Add it all up. This has to be a grounding problem aggravated by the wet season, and an underlying assumption that once you sink a ground it's good forever. It isn't.

    • Turns out the problem is frying fuses on the A&B cars and thyristors on the C cars.

    • by thegarbz ( 1787294 ) on Friday March 18, 2016 @04:21AM (#51720819)

      This has to be a grounding problem aggravated by the wet season

      Grounding problems are the cause of problems in the rail cars for many different reasons. My favourite is when an Australian train company decided to go green and implement regenerative breaking on all their equipment without any forethought. After purchasing an entire fleet of fancy new green trains they found the power goes out at the train station every time the train approaches.

      But really this is not helped by the fact that ground forms an important part of the electrical path in a rail system, and not just a safety mechanism as in most other cases.

  • by BoRegardless ( 721219 ) on Thursday March 17, 2016 @10:16PM (#51719735)

    I'm truly surprised that they don't have intensive real time monitoring with sensors through their whole system.

    Proper engineering and maintenance of such a critical system demands it.

    • by Hans Lehmann ( 571625 ) on Thursday March 17, 2016 @11:24PM (#51719977)
      Monitoring of what? Sensors through the whole system that measure what? What exactly is this proper engineering that you claim they should have done? Armchair engineers always seem to have perfect hindsight.
    • by Nemyst ( 1383049 )
      Have you seen the Bart? It's falling apart from all sides, the cars are old. Back then, real-time monitoring wasn't a thing.
    • If you're surprised that BART is lacking something remotely logical and/or basically requisite you don't understand BART or the non-Tech Industry side of the Bay Area.

      BART only funds repairs, no technical improvements what-so-ever. The most recent redesigns are ways to fit more standing people in each car since it raises rider count. In fact, the only technological changes I can think of having happened to BART in the 25 years I lived in the Bay Area was the upgrade to the Clipper Card system.

      Bathrooms in s

    • by thegarbz ( 1787294 ) on Friday March 18, 2016 @04:13AM (#51720809)

      I'm truly surprised that they don't have intensive real time monitoring with sensors through their whole system.

      Outside of a power generation company looking at maybe one or two substations away from their plant you'll find power infrastructure monitoring to the level that could aid predictive maintenance is non-existent. Even in utilities it's non-existent. Even in companies that don't run their equipment into the ground it's non-existent.

  • In the mid-70's I went with my parents to the bay area to meet some friends of theirs. They decided we needed to eat at a restaurant that required a BART ride. Keep in mind, back then BART was brand spankin new, ultra-reliable, much cheaper than gas. We never made it to the restaurant. I was like 10 years old, I have no idea why, But as an old fart nowdays whenever I think of BART I think "not gonna happen".

    On the other hand, that was the first time I saw Black Sabbath's Paranoid album. Didn't hear
  • by sjames ( 1099 ) on Thursday March 17, 2016 @11:01PM (#51719901) Homepage Journal

    It all started 2 years ago when a student majoring in EE took an exotic canoe trip on the Amazon. One day the canoe capsized while he was studying and his book sank to the bottom. Thee eels read voraciously and learned about series parallel wiring of batteries. An idea was born.

    And so now we have Electric Eels on a Train!

    • And so now we have Electric Eels on a Train!

      Is that better or worse than snakes on a plane?

    • by khallow ( 566160 )
      You spilled it too early, so now there will be copycat movies hitching a ride on your blockbuster. Prepare for Lampreys on a Barge and Rugrats in a Car. Coming to theaters near you!
  • This thread seems to explain many of Washington Post editorial cartoonist Tom Toles cartoons having very negative comments on DC's Metro. The continuous stream of cartoons point to constant problems with the system and inane explanations by its executives.
  • by MrKaos ( 858439 ) on Thursday March 17, 2016 @11:14PM (#51719937) Journal
    a cyber attack.
  • BART is finally coming to Silicon Valley. I'm so excited. Meh...

    http://www.vta.org/bart/ [vta.org]

  • So the first time was entering the tube at west oakland and the second time was between north concord and bay point? Yea I know I didn't RDFA but I think the info would be helpful here instead of possibly there.
  • It must be bunnies, bunnies, it must be bunnies! /Buffy

  • I wouldn't want to swap with those poor engineers working overtime to find out what's wrong here. as one myself, I know how desperate this can feel.

    On the other hand, there is no better feeling than finally finding the root cause. The better the more unconnected it seems to be at first sights. That's what you got your degree for.

  • All downtown BART stations have to be periodically taken offline so that human excrement can be cleaned out of the escalators.

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