MISC | 3rd Rail Powered Railways

[Sopomon]

Originally Posted by Suburbanist

I think Southern England suffers a lot with its 3rd rail network. You can't upgrade the electric tension, and it suffers a lot from snow and freezing.

I would like to see it change, but it's a huge expense that the current government will not be happy to make.

[trainrover]

Originally Posted by Suburbanist

it suffers a lot from snow and freezing.

Really, "a lot", i.e., snow?! Plus what overnight temperatures does their 3rd rail network suffer from?

[Suburbanist]

Originally Posted by trainrover

Plus what overnight temperatures does their 3rd rail network suffer from?

Temperatures that are low enough to freeze moisture and create packs of ice withing the covered live rail, particularly on rainy days.

[Nexis]

Originally Posted by trainrover

Really, "a lot", i.e., snow?! Plus what overnight temperatures does their 3rd rail network suffer from?

Its not a big issue , most 3rd Rail systems have blowers and machines to clean the snow and issue of the 3rd Rail. Catenary is more of an Issue with Snow and ice...

[trainrover]

Catenary

[goten2255]

he means the wires hanging above the railways and the trains use pantographs to reach the wires.

anyways its very interesting and unique how some railway systems in the world uses third rail (usually its caterney, diesel, or steam) like NYC's MTA Long island railroad and Metro North on some lines.

also southern england alot of the trains there uses third rail but it looks different then the ones in the Long Island Railroad and Metro North??

BART in san francisico uses third rail but that is considered more of a metro or is it?

[G5man]

Originally Posted by goten2255

he means the wires hanging above the railways and the trains use pantographs to reach the wires.

anyways its very interesting and unique how some railway systems in the world uses third rail (usually its caterney, diesel, or steam) like NYC's MTA Long island railroad and Metro North on some lines.

also southern england alot of the trains there uses third rail but it looks different then the ones in the Long Island Railroad and Metro North??

BART in san francisico uses third rail but that is considered more of a metro or is it?

BART is a suburban metro is the best way to describe it due to its spread of stations into suburban areas but has an urban concentration in Oakland and DT San Francisco.

[Nexis]

Long Island Railroad uses the same 3rd Rail as the Subway and PATH and thats Top Contact.

image hosted on flickr

LIRR by rocketdogphoto, on Flickr

image hosted on flickr

LIRR M7 7260 7669 by bigdan034, on Flickr

image hosted on flickr

LIRR Tracks. Woodmere, NY by scarlatti2004, on Flickr

Metro North , and the Market - Frankfort line use a Bottom Contact third rail.

image hosted on flickr

Day -364 - Harlem Line, Katonah by bTar~ikeda, on Flickr

image hosted on flickr

HPIM1466 copy by gambleg42, on Flickr

[joshsam]

Only metro trains use 3rd rail in Belgium.

[poshbakerloo]

Imagine have to rewire that...

(Clapham Junction, London)

[XAN_]

Nothing impossible. In Ukraine we have wired some really big stations in last decades. Of course, they were diesel, not 3rd rail.

[Momo1435]

Originally Posted by poshbakerloo

Imagine have to rewire that...

(Clapham Junction, London)

Actually it's not that difficult to wire this junction. It's only looks difficult because there are many tracks, but the tracks are already untangled without many connections between them. It doesn't look as complicated as many European stations, like Zürich for example. There you see many more connections between the different tracks with several "switch streets" in 2 directions. And it's all wired.

As a matter of fact, it's much easier to wire a complex junction then to use 3rd rail. On your picture you can clearly see many small sections of third rail that all have to be connected with each other underneath the tracks. With overhead wires there's only a need to connect the wires when they crosses, but that is not that difficult to do. And a train only needs one contact point with the wires to have a continuous energy supply. With the 3rd rail you need more contacts and that means more wear on both the trains and the infrastructure.

The only reason why the South East isn't wired is because of the costs.

[joshsam]

Originally Posted by poshbakerloo

Imagine have to rewire that...

http://i54.photobucket.com/albums/g9...nspring475.jpg


http://i54.photobucket.com/albums/g9...erlecht141.jpg


http://i54.photobucket.com/albums/g9...erlecht132.jpg

Will look like this.(Brussels , Belgium) Note that this was done 60 years ago, It can be done a lot cleaner I think.

Ps: For people who think 3rd rail suffers more from freezing or heat, I don't think so. In winter there are lots of delays due to powerlines that where frozen over here to.

[trainrover]

Originally Posted by goten2255

he means the wires hanging above the railways

I know he did. I'm just stunned ("") by catenary being more problematic wintertime than 3rd rail.

[Suburbanist]

Originally Posted by trainrover

I know he did. I'm just stunned ("") by catenary being more problematic wintertime than 3rd rail.

I don't think it is more problematic at all. A catenary is completely exposed to the sunlight, it is far from ground level where moisture concentrate, and it also more prone to dust accumulation.

For open-field operation, I'd say wire lines are a superior technology. The experiment of using 3rd rail, first deployed on subways, on large-scale systems operating on surface has been not that successful, reason for which it hasn't been adopted in many countries.

[trainrover]

I agree. Both the outdoor tube and SkyTrain suffered enormously from one or two cm of snow plus -5ºC temperature.

Maybe forummers here have been muddling up the intricate electronics inside recent models of trains suffering from 'meddlesome' snow and ice (TGVs and, before them, Montreal's outdoor EMUs)

[makita09]

Originally Posted by Suburbanist

The experiment of using 3rd rail, first deployed on subways, on large-scale systems operating on surface has been not that successful, reason for which it hasn't been adopted in many countries.

If we use the example of the only large-scale surface network, the southeast of england, then by what means has it not been successful? It has functioned exactly as intended and it will continue to do so for a long time. The pros and cons of the system today are exactly the same pros and cons that they were in the 1920s when the southern region group opted for L&SWR's 3rd rail system over LB&SCR's overhead system, the latter's extensive network of which was deleted and replaced with 3rd rail.

Pros

• Less stuff to build
• Less space required
• difficult to damage
• the route-clearing vehicles are needed anyway*
• Effective for 100mph operation
• Can operate in parallel with AC without needing neutral sections (modern benefit only)

Cons

• Low voltage DC only reducing absolute power and increasing losses
• Higher number of transformers (also suffered by 1500kV DC overhead systems)
• Sporadic nature of circuit contact causes modern digital trains problems
• More dangerous for track workers and trespassers

* The route clearing vehicles are needed for leaf and dirt clearing which cause FAR more problems in the south east than snow and ice-related power problems do. The cleaning vehicles are diesel powered and can clean snow or leaves - its easy. Snow-related catenray problems are not so easy to fix.

The vast majority of snow and ice problems in the south east are due to the system mangament of the electrostar EMUs - which now spend a large proportion of the year in 'winter mode' to stop it detecting a dangerous power surge that is actually just a bit of ice and not a surge at all.

The drawbacks of 3rd rail are not that significant in the UK. It was locked in by the decision in the 1920s, and those who made the decision knew full well that it would lock 3rd rail in for the forseeable future. Whilst any new networks would never be considered to be 3rd rail, indeed they are legally prevented by the Office of Rail Regulation, extensions of the 3rd rail network are still allowed as the marginal cost is much more sensible than the whole new cost of a new isolated local overhead system. And converting 1200 miles of double, triple, quadruple and even octuple and duodecuple track, along with every one of the thousands of transformer feeding stations, adjusting hundreds of bridges, lowering hundreds of miles tracks under bridges and in tunnels, re-sighting signals and commissioning pantographs on the 3rd rail EMU's (most of which are designed to be converted if necessary) is a massive undertaking, and not likely to be passed any time soon. We're talking many many billions of pounds to obtain an electrification system that does exactly the same thing as the one we've already got. Is not an 'experiemnt that has failed' - it is a different design of system that fulfilled and fulfills its design criteria. Remember the 3rd rail network was concieved as a metro system - the longer distance services still being operated by steam at the time, but has been extended as time progressed because it turned out to be fine for outer suburban and medium distance ops as well. Not as a 'new' system, but as a marginal investment it made and continues to make sense.

3rd rail is not a commercial product to be viewed as a commercial success or not, it is an engineering solution and a perfectly valid one at that.

[hammersklavier]

In the Philadelphia suburbs, there's the Norristown High Speed Line with is quite possibly the weirdest operation anywhere in the country. Too heavy for light rail, too light for heavy rail, too suburban for a metro, too short (carlength-wise) for a commuter operation...the only description that does it some justice is "interurban", but that's because we've all forgotten what an interurban actually looks like.

Here's a picture of it:

Source

Those things go quite quick too.

[trainrover]

Wherein gaps in its 3rd rail appear longer than the cars themselves (see 0'20") and possibly problematic (4'35"):

Originally Posted by Nexis

A Front ride on the Norristown High Speed line.

[trainrover]