tisdag 15 maj 2007

What will replace the High Speed Train - the story continues

The Department of Transport continues to develop its specification for the replacement for Britain's Inter-City 125 trains (HSTs). The actual work is being done by consultants Mott MacDonald, who have been paid several million pounds for work so far. The specification for the new train, now referred to as the Intercity Express Programme, continues to escalate. In reality, it is likely to turn out to be little more than an expensive wish-list; the aim now is for a very lightweight train with modern standards of crashworthiness, powered by either diesel or electricty with the option for changing over en-route, with Virgin Voyager standards of acceleration and a top speed of 140 mph. That is asking for a lot.

Whether there is a need for such a train at all is debatable. Some routes on which the HST fleet is used need to be electrified, as the stations are close together and the traffic is dense. These include the Great Western Main line to Bristol and Cardiff, and the Midland Main Line to Nottingham, Derby and Sheffield. Once the routes were electrified, electric multiple unit trains as used on services out of London (Waterloo) to Portsmouth, Bournemouth and Weymouth would be suitable. A run-on build of a 25kV version of the Siemens class 444 would do nicely.

This leaves the East Coast Main line from London to Edinburgh and Aberdeen, which is unlikely to be electrified north of the Scottish capital, and the Great Western line to Devon and Cornwall, which again is unlikely ever to be electrified beyond Bristol. For these routes, some other form of traction will be needed, referred to as "self-powered", but in reality likely to be diesel.

One of the key factors in the specification for the new trains is the wish for high speeds. What seems to be little understood is the way in which the costs of railway operation rise exponentially with speed. There is twice as much energy in an object moving at 140 mph than there is at 100 mph. Also, at the higher speeds, air resistance becomes an increasingly important factor in energy consumption. Vehicles must be heavier as it becomes more difficult to make them adequately crashworthy. The design of systems such as signals, suspension and brakes is more critical. The track has to be kept to a much higher standard. There is more wear and tear on everything. All of which drives costs up exponentially.

At the same time, increasing speeds bring diminishing returns. Every additional speed increment cuts the journey time by a decreasing amound. A 100 mile journey takes 80 minutes at 75 mph, 60 minutes at 100 mph and 48 minutes at 125mph - the first 25 mph increase saves 20 minutes but the second one saves only a further 12 minutes. Where there are a lot of people making journeys of 300 miles or more, as on the Continent, then the higher speeds are worth having. In Britain, however, where 85% of the population lives within 150 miles of, say, Leicester, the median long distance journey is probably around 100 miles, which is catered for very well by electric multiple unit trains with a top speed of around 100 mph - the sort of thing that South West Trains is using.

There is a case for dedicated high speed trains between London, Newcastle, and Edinburgh and Glasgow, but for the rest, flexibility and capacity are key, with ordinary carriages capable of being operated in push-pull mode by any form of traction, and with a top speed of no more than 100 mph. This seems to be the most common type of train over much of Continental Europe, where multiple unit trains tend to be confined to suburban routes around the larger cities.

A welcome straw in the wind, therefore, is the announcement of the formation of a new rolling stock leasing company, Sovereign trains, which is about to place an order for three new trains, to be built in China, similar to the HSTs, for a new service to be run by Grand Central Trains between Sunderland and London. These will have a locomotive at each end, like the HSTs, but the carriages, or a similar version of them, will be suitable for any form of traction, in push-pull mode.

The interesting thing about the carriages is that they appear to be to the design developed by British Rail Engineering in the 1980s. These were known as the "International" and based on the Mark 3 coach used in the HSTs. BREL sold a complete factory to build the International design in China. The demonstration train built for British use went to Ireland, so at last British passengers will enjoy the benefit of this excellent design, which was a major improvement on the mark 3. (artist's impression above) They resemble similar carriages built in the 1980s and used all over the Continent except on the dedicated High Speed Lines - such as the French Railways' Corail and similar vehicles running on the German railways. If there was to be an outbreak of commonsense, the Department of Transport would stop pouring money away on consultancy and watch this development carefully, as a large standard fleet of such vehicles, and suitable electric and diesel locomotives to power them, could be exactly what is needed on Britain's railway in the foreseeable future.

Grand Central Railways plans new train services

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