How do subways work and why can't this concept be applied to garden railroading?

[Star Trek]

How come subways are powered by only one rail and electric toy trains are powered by two? If garden trains were powered by only one rail, track cleaning would be quicker and easier.

[cabbage]

I am not sure how the US system works -but the three rail system used in the UK is that the "Third Rail" contains the positive 720V DC and the two other rails act as the return. This is EITHER in the centre (London Underground) or on the inner of the two sets of tracks (Southern Region).

Track cleaning will always be a part of current collection if fed via rails. The London Underground is switched "off" between 2am and 4 am for cleaning. Southern Region have selfpropelled sand blaster track wagons to clean the rails.

No-one has ever solved the problem of "leaves on the line".

Even the modern Eurostars leaving London via the three rails of Southern Region still get jerky until they hit the overheads and raise pantographs when going into the Channel Tunnel.

regards

ralph

[Great Western]

Greetings

       Mainline UK systems are third rail plus overhead systems as Cabbage correctly states.  However the Lon don underground system operates on a FOUR rail system.     

[cabbage]

YES! I and several other people are well aware of the negative fourth rail!!!!

When I was shown around the "old" Golders Green rectifier installation I was most firmly instructed NOT to walk on any area of the floor that was painted GREEN. I was initially puzzled but on entering the rectifer room with the DOZENS of glass Mercury Arc rectifiers that only colours that could be seen where bright blue/white, black or GREEN. I looked at the area painted green and understood, if you stood on a green area you were standing between the positive and negative outputs of the rows of rectifiers!!!

regards

ralph

[dwbeckett]

BART run's on three rail concept power is supplied from the third rail on eather side of the train . BTY Bay Area Ripid Transit. The EL in Philadephia is operates the same way as does the Metro in Washington DC. Since LS run's on DC current the only 3 ways to run trains is two rail track power, self contained Battery power and overhead cantenary system. all require a Plus and Minus contact. so If you dont desire to clean track GO BATTERY.

[GP-9_Man11786]

The New York City Subway and the Long Island Railroad use three rails. It's basically the same as 3-rail o-gauge. The thrid rail is positive and the other rails act as the return, as noted above. You could apply this concept to a garden railway simply by using 3-rail o-guage

[Ray Dunakin]

When I saw the subject heading, I thought maybe you were interested in modeling a subway. Now there's an idea -- just stick a few miniature stairwells around the garden with signs indicating station names, and you're all set! No track cleaning, no expensive locos or rolling stock, no wiring or construction. Just tell everyone it's all underground! :)

[tomikawaTT]

When I saw the subject heading, I thought maybe you were interested in modeling a subway. Now there's an idea -- just stick a few miniature stairwells around the garden with signs indicating station names, and you're all set! No track cleaning, no expensive locos or rolling stock, no wiring or construction. Just tell everyone it's all underground! :)

MisterBeasley, over on the Model Railroader forums, has a subway that has surface features just like that.  His stations can be seen at the table edges, but the best view is from the TV camera in the head end car of his subway train.

Speaking of third rails - the NYC subways have overrunning third rail, somewhat protected by a board over the top on the old IRT lines.  The ex-New York Central third rail was underrunning - contact surface on the bottom, with the whole rail wrapped in insulation.  The latter was less prone to hiccups, since things that would just lay on the top-running subway rails wouldn't stick very well to the underside of the underrunning rail.

Chuck (former New Yorker)

[rpc7271]

Subways use an overhead wire instead of the other rail. Outdoors this overhead system results in even more maintenance that a 2 rail system. Besides an underground garden railroad would be hard to see or enjoy but it would leave more room for plants.

[tomikawaTT]

Subways use an overhead wire instead of the other rail. Outdoors this overhead system results in even more maintenance that a 2 rail system. Besides an underground garden railroad would be hard to see or enjoy but it would leave more room for plants.

Sounds like light rail that happens to run in a tunnel for part of its route.  The only true (all-underground) subway with pantographs that I've ever seen was a newer line in Tokyo- and the "wire" was a small section T rail suspended from the tunnel roof (which, I admit, is a rather odd location for a third rail.)

Chuck (modeling Central Japan in September, 1964)