Comments on: CBTC tests on L line a bit jerky

By: Platform glitch plaguing CBTC L trains :: Second Ave. Sagas | A New York City Subway Blog

Wed, 10 Jun 2009 05:16:00 +0000

[...] time technical problems have popped up in regards to the CBTC program. Last month, I wrote about jerking motions and breaking problems aboard the CBTC trains. What is interesting this month, however, is Haddon’s [...]

By: The Secret Conductor

The Secret Conductor — Sun, 24 May 2009 23:58:24 +0000

firstly the L train reaches speeds up to 45mph and in the tube it comes close to 60mph (this is the biggest timesaver and tends to put the train ahead of schedule by almost 2 minutes). I think that is the optimal speed considering proximity of each train station to each other.

secondly OPTO can only really work from midnight to 5:30am due to the amount of passengers on the train (its the reason why the conductor was brought back on some Rockaway shuttles due to the beach crowd). even then people would complain about safety of having 1 person on a 8 car train. not even most cops (when its just 1) go in the last cars with 2 people on the train. then there is the problem of people riding the side of the train or falling against the train while the train is taking off.

and totally forget about asking questions in route cause it aint happening.

By: AlexB

AlexB — Wed, 20 May 2009 21:33:57 +0000

Is 40 trains per hour the maximum that the best technology will allow today? Could we ever get that on the L train? Even exploding Williamsburg couldn’t fill up a train line if they are coming every one and a half minutes…

By: Cap'n Transit

Cap'n Transit — Wed, 20 May 2009 21:01:18 +0000

An uncomfortable jerk? On the subway?

By: anonymouse

anonymouse — Wed, 20 May 2009 20:16:41 +0000

Yet for some reason, St. Petersburg and Kharkov (and possibly other cities as well) have automation. By the way, all trains in Moscow Metro are OPTO except the ones on lines 3 and 4, which still have old style wayside signals with trip stops and no cab signals/ASC (something that I think might change soon: they changed the signal system on Line 1 not too long ago). By the way, there’s also been no interest in CBTC in Russia at all. I think they’re happy enough with the capabilities of coded track circuit fixed block signalling, and more importantly with its general reliability, which is important when you’re running 40 trains an hour.

By: Adam G

Adam G — Wed, 20 May 2009 20:16:31 +0000

There’s a reason Siemens is always the lowest bidder on transit projects. The MTA needs to disqualify them and start dealing with companies that actually intend on following through.

By: Alon Levy

Alon Levy — Wed, 20 May 2009 17:45:56 +0000

Russia overall has really a strong public works mentality in the public sector. The communist-era companies, even those that were nominally privatized, end up in the hands of the managers or the workers, who like any solution that involves more jobs. It won’t surprise me if Moscow Metro resists automation for the same reason the TWU does.

By: Benjamin Kabak

Benjamin Kabak — Wed, 20 May 2009 17:38:59 +0000

That was the bus arrival board project. Siemens sure seems ultra unreliable for transit projects.

By: herenthere

herenthere — Wed, 20 May 2009 17:29:38 +0000

Well, all that is required is just a readjustment in research and programming. A computer can be easily programmed to “ease off” at the end.

And didn’t you report that CBTC was abandoned by Siemens and instead developed by in-house technicians?

By: anonymouse

anonymouse — Wed, 20 May 2009 17:17:10 +0000

Automated train operation is generally just not as good as a (competent) manual driver, because of the limitations of technology. A driver will tend to have a constant brake rate, easing off a bit at the very end, while the computer, being more cautious, will slow down a bit earlier, coast, then apply full brake to stop at exactly the right spot. Going from full brake to stopped is what causes the jerk, and you can see it in many automated systems including the AirTrain. And it seems that overall, this is slightly less efficient than manual driving, which is why in Moscow where they run 39-40 trains an hour on some lines, all the trains are manual, even though they have had the technology for automation for at least a couple decades now.