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Choreographing HS2

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Shinkansen map (Wikipedia) The degree of connectedness with pre-existing assets is often an important consideration in the design of new railways, especially high speed rail. Japan’s Shinkansen high speed railways are separate from the country’s legacy railway system, which uses narrow gauge track.

In Spain, the government decided to build new high speed lines – and convert 1668mm Iberian gauge legacy tracks – to the de facto standard 1435mm. In the event, hardly any of the legacy network has been converted to, or dual-gauged for, 1435mm, but variable gauge trainsets are used to allow no-change journeys beyond the confines of the high speed network.

In France, Germany, and Italy, there is generally more interplay between high speed lines and the legacy tracks, but interoperability may be restricted by factors such as gradients (e.g. on the Frankfurt to Cologne Neubaustrecke), so conventional trains cannot use new-build tracks, even where this might make sense.

Segregation allows high speed rail to be optimally engineered, and isolates the system from perturbation present in the wider rail network. On the other hand, an open system allows connection to a much larger destination-origin set. HS2 is a sort of halfway house between the segregated (Shinkansen-type) and run-off (TGV-type) concepts. Even in phase 2, the Y-network, a large amount of HS2 traffic would be run-off (beyond Manchester and Leeds), involving use of the legacy system.

With dependence on interrunning with the legacy system, discussion of how and whether 18 trains per hour is possible on HS2 track becomes academic. Trains would need to be fed from the legacy system into HS2 like clockwork, to allow safe separation. The likelihood of this being achieved, is effectively nil.


Written by beleben

November 11, 2011 at 6:04 pm

One Response

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  1. […] examined HS2′s unusable capacity, lumpy blobs, and spacing requirements, it might be worth taking another look at capacity realities, as they apply to train […]

    HS2 train capacity « beleben

    November 24, 2011 at 6:50 pm

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