Configuring the track

Australia’s low population density means that the track length per station will be relatively high when compared to European or Asian rail networks. The upshot of this is that capital costs will greatly dominate the total cost of any railway system – the cost of rollingstock will be comparatively minor. Capital costs must therefore be reduced as much as possible while keeping performance within acceptable parameters. For our purposes, we’ll define “acceptable” as having a maximum operating speed of 200km/h or greater.

Far and away the greatest cost will be the construction of the alignment itself, that is, the tunnels, bridges and earthworks required to create a flat and straight enough platform for the railway. There are two ways to reduce this cost – first, reduce the design speed so that the alignment doesn’t have to be as flat or as straight, and second, use existing alignments wherever possible. This additionally reduces the design burden, as large portions of the alignment have already been designed and built.

Power infrastructure for electrically driven trains (catenary wires, transmission infrastructure, etc) adds a significant cost – up to several million dollars per kilometre, depending on design speed. It can be done away with completely if diesel-electric trainsets (referred to as Diesel Multiple Units or DMUs) are used.

Finally, in order to minimise the difficulty of modifying the existing track, we want the curve radii to be as tight as possible. This means we have to use tilting trains. Although a tilter is more expensive than a regular train, it lets you re-use much more of the existing alignment. There are numerous tilting DMUs in service with a top speed of 200km/h or above, such as the German ICE-TD, the British Class 221 Super Voyager, or even Australia’s own QR Tilt Train from the Cairns line.

In summary, to keep costs low:

  • Use the existing track
  • Use diesels
  • Use tilters

In the next few posts we will look at track geometry and railway dynamics in more detail, and decide what minimum curve radius will be acceptable – this will become the primary constraint when designing the modifications to existing alignments. We will also come to an estimate of the cost per kilometre of rail infrastructure, and also bridges, tunnels and earthworks.

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