# Compatible 3rd Rail Systems



## VentureForth (Jun 5, 2013)

SO - I think that MARTA in Atlanta and METRO in DC use the same basic track/car system. What other systems are compatible? I know several have actual different rolling stock, but which light rail systems are compatible with each other - ie: Voltage, signalling, automation or lack thereof, etc. I mean, can you operate a MARTA train on the Chicago loop?


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## trainman74 (Jun 5, 2013)

VentureForth said:


> I mean, can you operate a MARTA train on the Chicago loop?


In this specific case, I can say no even without any knowledge of the voltage, signaling, etc. -- the curves and clearances on the Loop (and much of the rest of the Chicago 'L' system as well) would be too tight for the MARTA equipment.


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## Ryan (Jun 5, 2013)

I would be very surprised if there were any major systems that could interoperate without some modifications.


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## afigg (Jun 5, 2013)

VentureForth said:


> SO - I think that MARTA in Atlanta and METRO in DC use the same basic track/car system. What other systems are compatible?


Beyond the gauger, 3rd rail DC power, signaling, the dimensions, clearance, dynamic clearances, platform height also would have to be compatible. According to wikipedia, the Baltimore subway (line) and Miami Metrorail are compatible because they placed a combined order for rolling stock when placing their first equipment order.
The DC Metro and MARTA started design and final development around the same time with DC Metro starting construction a few years earlier in late 1969. The equipment is very similar but how close they are in specs and operational capability, don't know. Both systems and operating agencies are now big enough, that would be little benefit in placing a combined order. WMATA, for example, is placing a rather large order from Kawasaki for 528 Series 7000 cars for the Silver Line, and to replace the Series 1000 & 4000 cars.


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## George Harris (Jun 6, 2013)

Google and Wikipedia are your friends here. Look up each of these systems and see what you can find and you should be able to answer the most part of your own question


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## DET63 (Jun 6, 2013)

I know that BART equipment, which operates on what is sometimes called Indian gauge, i.e., 1,676 mm (5 ft 6 in) wide track, would not be immediately compatible with most other subway/rapid transit/metro systems in the U.S., including the S.F. Muni.


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## George Harris (Jun 7, 2013)

DET63 said:


> I know that BART equipment, which operates on what is sometimes called Indian gauge, i.e., 1,676 mm (5 ft 6 in) wide track, would not be immediately compatible with most other subway/rapid transit/metro systems in the U.S., including the S.F. Muni.


Bart power is also 1,000 volts DC. Most of the other newer systems (WMATA, MARTA, etc.) are 750 VDC. New York, Chicago, and most other of the older systems are 600 VDC. At least most are overrunning third rail. The ex-NYC Metro North is underrunning third rail.


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## DET63 (Jun 8, 2013)

George Harris said:


> DET63 said:
> 
> 
> > I know that BART equipment, which operates on what is sometimes called Indian gauge, i.e., 1,676 mm (5 ft 6 in) wide track, would not be immediately compatible with most other subway/rapid transit/metro systems in the U.S., including the S.F. Muni.
> ...


All of this means that BART's rolling stock just about has to be specially built--and thus is more expensive. I believe most of its equipment has been in use from the start (though occasionally remodeled/upgraded).


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## jis (Jun 8, 2013)

Subway equipment generally has to be specially built, specially for older systems, since they have their own odd loading gauge and dynamic envelope characteristics. But then again for large systems like New York, that is not a problem, since their orders tend to be enormous anyway. But they do have two completely different loading gauges and dynamic envelopes for the A and B divisions.


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## DET63 (Jun 9, 2013)

jis said:


> Subway equipment generally has to be specially built, specially for older systems, since they have their own odd loading gauge and dynamic envelope characteristics. But then again for large systems like New York, that is not a problem, since their orders tend to be enormous anyway. But they do have two completely different loading gauges and dynamic envelopes for the A and B divisions.


While that seems odd, it merely reflects that, for many years, New York had two, then three, subway systems: first the IRT and BMT, then later the IND, which was compatible with the BMT. (PATH is a wholly separate critter.) Other subway systems in the world may have similar issues, however, with either different track gauges, different loading gauges, different signaling systems, different voltage requirements, etc., being used by one part or another.


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