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Dynamic Capacity a blessing for Light Rail December 14, 2009

Posted by schiltec in Capacity, Dynamic Capacity, Light Rail systems.
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Matching capacity with demand brings real service while saving costs

Trams and Light Rail systems deliver always*) a fixed amount of ‘potential passengers’ to a station. For all stations, big or small, the amount is fixed and the same.

*) In many tram systems, in addition to the basic arrangement, ‘peak hour long consist’ can be formed in the yard. This cumbersome practice (it has nothing to do with ‘dynamic capacity’) is costly and only justified in rare circumstances. Most modern systems have abandoned it.

A dynamic capacity system changes its capacity constantly by coupling and uncoupling carriages to and from a consist, now called a wave. How many carriages have to be uncoupled is determined by a computer who monitors and anticipates demand. In low times it instructs particular drivers to divert to the yard. Quite naturally, when many passengers want to alight – at a main station or where a sport event is on – more carriages than the usual single car will be uncoupled. How many carriages are coupled does not need a computer as simply all carriages on the track are picked up. When anticipating increased traffic the computer would also request additional cars to move onto the line track.

For the system to work the following is needed:

  • Each car is motorized and self contained.
  • Each car has a driver. In fact the ‘driver’ drives only a small percentage of her/his time and is more of a ‘maitre de cabin’, looking after passengers.
  • Cars have automated couplings and have wide passages between themselves for passengers to pass through.
  • The maitre de cabin has a wireless connection to a computer who tells her/him how many passengers are allowed to board. For the convenience of passengers, this ensures that a wave is never overfilling.

Uncoupling itself is not done by the computer but by the ‘maitre de cabine’ on request of the computer. This is because before being able to split the maitre de cabin has to close the two end doors separating the two carriages.

Also, because a wave does not stop at a station it can be longer than the length of a station and this is why dynamic systems have much greater capacity than traditional trams.

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1. Waverail – a 21st Century Tram System « The Gold Coast Rapid Transit Project - December 15, 2009

[…] is an Australian developed dynamic capacity system. In the form of road based light rail it operates at 39 – 45km/h. But Waverail’s main home […]


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