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What's Frying the Electrical Systems On BART Trains? (ieee.org)
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.
Yes, just think if actual personal automobile costrs were directly born by the users, they would run screaming.
Instead it gets widely subsidized in invisible ways.
And you outsourced your spell checking? "Cheeper", really dude?
...when all their money is going to high salaries and benefits for union employees?
Over 200 BART employees earned over $200,000 a year in total compensation...
Lawrence Person (lawrencepersonh@gmailh.com (remove all "h"s to mail)
http://www.lawrenceperson.com/
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. 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
"BART is about equally priced to driving for a single person, and significantly more expensive for multiple people (i.e. versus carpool)."
If youre driving into the city, this is not true at all unless your employer has free parking. Most of the cost of diving into the city is paying for parking, which is anywhere from $30 - $80 a ~day~.
The vast majority of BART ridership and hell-like experience is into the city in the morning and out again in the evening...if youre traveling from any other BART stop to any other, its not that bad at all.
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.
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