# Wireless HS train?



## Shawn Ryu (Aug 29, 2014)

http://m.koreaherald.com/view.php?ud=20140521001091&ntn=0

How bout that, could save billions on electrifications of railroad tracks once the technology is perfected down the road.


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## Paulus (Aug 29, 2014)

These are going to be more expensive and less energy efficient than overhead catenary, there's no reason to actually pursue it.


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## Shawn Ryu (Aug 29, 2014)

^At the moment. But more research and development can make it more economically feasible

Besides they already have trams running on similar technology.


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## Paulus (Aug 29, 2014)

It's really not going to be more feasible than overhead electrification; the catenary is cheap and the increased power demands of this system thanks to inefficiency are going to size up the most expensive part, the substations.


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## jis (Aug 29, 2014)

Nothing transfers power as efficiently as direct contact, though high frequency induction (essentially an air transformer coupling the vehicle to the track mounted coils) may come close if engineered right. However, please note that all that one is doing is replacing overhead catenary with underground induction coils, and I find it hard to believe that the latter will be substantially cheaper, if at all.

The question in any engineering venture though is to understand the tradeoffs between cost, efficiency and several other engineering factors and then make the right choice.


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## Paulus (Aug 29, 2014)

Wouldn't adding this to existing track require a complete reconstruction of the track bed in order to place it underneath?


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## jis (Aug 29, 2014)

Paulus said:


> Wouldn't adding this to existing track require a complete reconstruction of the track bed in order to place it underneath?


More or less yes. So Shawn's claim that this will be cheaper than OHE is more or less unfounded on any reasonable set of assumptions about what it will take. The major difference is aesthetic, not financial, and indeed it will most likely cost more than OHE, just in the cost of copper and power electronics over and above the construction cost. There will be savings in galvanized steel poles though


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## George Harris (Aug 30, 2014)

How about some expansion on "They already have trams running on similar technology" because I can't think of what you are referencing.

How much undertrack space is required for this system?

This system sounds a lot like Maglev without the levitation but with rails instead. The Japanese, who have both, have stated that maglev has much higher energy consumption than the Shinkansen trains.


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## Green Maned Lion (Aug 30, 2014)

A solution looking for a problem.

I seriously thought you were going to talk about either turbines (stupid) or Tesla style swappable batteries (less stupid, but still stupid).


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## jis (Aug 30, 2014)

George Harris said:


> How about some expansion on "They already have trams running on similar technology" because I can't think of what you are referencing.
> 
> How much undertrack space is required for this system?


George, here is a reference that roughly describes the Bombardier system. Alstom has something similar:
http://www.railwaygazette.com/news/single-view/view/primove-catenary-free-induction-tram.html



> This system sounds a lot like Maglev without the levitation but with rails instead. The Japanese, who have both, have stated that maglev has much higher energy consumption than the Shinkansen trains.


Maglev has three components:
1. Levitation system,

2. Linear Induction Motor Drive

3. Inductive power supply.

This is just item 3 used with regular steel wheel on steel rail track.

There are the VAL systems which have contact power supply but use LIM for movign the vehicles on either steel wheel on steel rail or rubber wheel on concrete rails.


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## Paulus (Aug 30, 2014)

George Harris said:


> How about some expansion on "They already have trams running on similar technology" because I can't think of what you are referencing.


Bordeaux and Reims.



> This system sounds a lot like Maglev without the levitation but with rails instead. The Japanese, who have both, have stated that maglev has much higher energy consumption than the Shinkansen trains.


Lower energy consumption for maglev at the same speed though as I recall.


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## Tokkyu40 (Aug 30, 2014)

Japan uses linear induction motors in Tokyo's Ooedo subway to reduce the size of the trains and the tunnels that have to be dug.
The Bordeaux tram uses a flush mounted third rail between the rails, built in short sections which are only energized while the trains are on top of them. It avoids the losses of induction, but has 3 times the cost of overhead lines, so the trams use pantographs outside the historic district where they can't use overhead.


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