Subway third rails and third rail power

Discussion relating to the past and present operations of the NYC Subway, PATH, and Staten Island Railway (SIRT).

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keyboardkat
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Subway third rails and third rail power

Post by keyboardkat » Thu Nov 25, 2010 1:38 pm

Both Metro-North and the LIRR have boosted their third rail voltage from the original nominal 660 v.d.c. to 750 v.d.c. in the interests of improving train performance and reducing voltage dropoff with distance from the substations. Yet the subway system still uses the old 600 v.d.c. standard inherited from the street railway industry in 1904, and still has some motor-generator or rotary converter substations.

I know money is an issue right now, but have there been any plans for the NYCTA to follow suit? Also, the LIRR replaced its all steel third rails (except on certain yard trackage) with new third rails consisting of a steel I-beam sandwiched by two aluminum strips, one on each side, to provide greater efficiency and conductivity, and to, again, reduce voltage drop with distance from substations. M-N, with its underruning third rail system, can't do so as easily but I have seen all-aluminum third rail installed, experimentally at least, on some platform tracks in Grand Central. Once again, is the subway system to be left behind? I guess the present power distribution system works well enough, but...
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Kamen Rider
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Re: Subway third rails and third rail power

Post by Kamen Rider » Thu Nov 25, 2010 8:20 pm

the railroads uped thier volatage becuase the M-series came with a higher voltage rating to handle longer trips at higher speeds. Subway trains are, at most, doing 50 and are going to stop again within the next two minutes 99% of the time. Railroad trains, esspecialy the really limited stop trains, can go 20-30 miles without stoping at 50-70 MPH.

upgrading to 750 on the TA would be a waste of money
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HBLR
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Re: Subway third rails and third rail power

Post by HBLR » Fri Nov 26, 2010 7:21 pm

PATH has the "booster" rail setup, but they go faster with heavier equipment than the subway, also it is technically a railroad all be it a rapid transit type setup. I think the subway's power systems will see new feeder lines and new rails and tracks etc before the 3rd rail is changed. There's a lot of it too, would be massively expensive, not to mention when you work on the 3rd rail you disrupt normal service entirely.
No I'm not a railroad professional, but that doesn't mean I can't provide first hand observational comments.

Patrick Boylan
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Re: Subway third rails and third rail power

Post by Patrick Boylan » Fri Nov 26, 2010 8:03 pm

Now you're forcing me to revisit the NY transit museum. I remember reading at least one of their placards which boasted that New York work crews do not turn off the 3rd rail. Have they become more safety conscious?

pennsy
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Re: Subway third rails and third rail power

Post by pennsy » Fri Nov 26, 2010 10:14 pm

According to the engineman of a Metrorail subway, Los Angeles, all MODERN US subways use 750 VDC.

keyboardkat
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Re: Subway third rails and third rail power

Post by keyboardkat » Sat Nov 27, 2010 11:05 pm

HBLR wrote:PATH has the "booster" rail setup, but they go faster with heavier equipment than the subway, also it is technically a railroad all be it a rapid transit type setup. I think the subway's power systems will see new feeder lines and new rails and tracks etc before the 3rd rail is changed. There's a lot of it too, would be massively expensive, not to mention when you work on the 3rd rail you disrupt normal service entirely.
What about the light "umbrella profile rail" third rail used under 6th Avenue, has that been replaced?
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keyboardkat
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Re: Subway third rails and third rail power

Post by keyboardkat » Mon Nov 29, 2010 7:07 pm

Patrick Boylan wrote:Now you're forcing me to revisit the NY transit museum. I remember reading at least one of their placards which boasted that New York work crews do not turn off the 3rd rail. Have they become more safety conscious?
Once I had a job assignment in Hewlett, NY, and during lunch I wandered over to the LIRR station. A work crew was replacing the old glass/ceramic third-rail insulator-supports with new asbestos third-rail chairs, as has also been done on the subway in many locations. One crew member used a wooden lever under the third rail, using one of the running rails as a pivot, to lift a short length of the third rail. The other crew member lifted out the old insulator and inserted a new one. He often grasped the third rail with both hands.

I said, "The power is off, right?" He said, "No, the power is on." I said, "but...." He said, "Just so you don't touch this (indicating a running rail) at the same time." He had on heavy work boots which must have had thick rubber soles. Still, he had more guts than I would have. There's always the chance to accidentally ground yourself, and get fried.
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HBLR
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Re: Subway third rails and third rail power

Post by HBLR » Mon Nov 29, 2010 8:26 pm

I meant replacing the 3rd rail segment. Sorry for not specifying. As for the specs on the conductor rail on 6th ave line, i do not know.
No I'm not a railroad professional, but that doesn't mean I can't provide first hand observational comments.

keyboardkat
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Re: Subway third rails and third rail power

Post by keyboardkat » Tue Nov 30, 2010 6:02 pm

HBLR wrote:I meant replacing the 3rd rail segment. Sorry for not specifying. As for the specs on the conductor rail on 6th ave line, i do not know.
I meant the third rail on the PATH 6th Ave. line. The third rail there is, or was, a type called "umbrella rail." Flat on top, slanted downard on either side, and with no web or base.
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HBLR
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Re: Subway third rails and third rail power

Post by HBLR » Wed Dec 01, 2010 6:17 pm

I usually sit on those trips as they tend to be a bit long, but i'll look next time i'm up on the 33rd street line.
No I'm not a railroad professional, but that doesn't mean I can't provide first hand observational comments.

Passenger
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Re: Subway third rails and third rail power

Post by Passenger » Thu Dec 02, 2010 12:53 pm

There are still rotary converters in use? Where?
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keyboardkat
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Re: Subway third rails and third rail power

Post by keyboardkat » Thu Dec 02, 2010 9:06 pm

Isn't there one still operating somewhere around Brooklyn Bridge? I think the building is sort of semi attached to one of the Federal buildings down there.
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HBLR
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Re: Subway third rails and third rail power

Post by HBLR » Sun Dec 05, 2010 11:26 pm

That sounds familiar kat, but when i think subway power i don't think rotary converters, i think DC substations and the big old power house. I'll have to do some digging.
No I'm not a railroad professional, but that doesn't mean I can't provide first hand observational comments.

HBLR
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Re: Subway third rails and third rail power

Post by HBLR » Mon Dec 06, 2010 4:00 am

It looks like, based on info i've found, there were several rotary converters for the "IRT". I believe this was to overcome the natural limitations to DC transmission from the power house on the river.

If one was related to a federal building, it may have shared street level access or been in the basement etc. The spacing is said to have been 2 miles, but i'm not sure how correct that is.
No I'm not a railroad professional, but that doesn't mean I can't provide first hand observational comments.

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