lördag 2 januari 2010

Steam traction for the 21st century



Illustrations from Dampflokomotiv- und Maschinenfabrik DLM AG
This nice looking 4-8-4 has been proposed for a standard gauge continental commuter railway which carries little off-peak traffic and has been threatened with closure. It has tourist potential since it runs through attractive countryside. But such a locomotive could possibly be acceptable in the first instance for more general commercial applications, in particular, infrastructure trains, currently worked by GM class 66. These are are now falling foul of emission standards regulations as they are 2-stroke diesels, and there are also issues with noise in the cab.

One typical inefficient use for class 66 is for trainloads of ballast. They are driven to the works site and then stay there for a whole weekend, often with the engine running all the time! A fleet of ten is used for infrastructure trains on the London Underground, if I recall, where they are obviously less than ideal in the tunnel sections. Transport for London could presumably change to something more suitable and the diesels redeployed. London Transport retained steam for a few years after British Railways because of the expense of new diesels.

Niche applications for steam
A recent picture of a Eurostar train being rescued by a couple of diesel locomotives demonstrates perhaps the kind of niche work this type of locomotive might initially find in mainstream use. Other typical uses would be engineering, construction and infrastructure services, and rolling stock delivery and transfer, for example between main works and depots. If there was going to make a breakthrough, it would come first in that area. After that, there is the replacement fleet for the railbuses and possibly for tourist/museum lines struggling to keep their ancient relics running with declining numbers of volunteers, but that would be a smaller locomotive.

In a sensible world there would also be a place for steam on main lines that are not likely to be electrified within the next 25 years ie the outer fringes of the national network, plus freight generally. Unfortunately, instead, the government has imposed a very expensive hybrid electric-diesel passenger train on the railways, costing £4 million per vehicle, whilst serviceable stock will go for scrap prematurely.

What diesels cannot do
It seems to me that the advantages over a class 66 diesel for these niche applications would be lower capital cost (presumably less than half); reduced fuel costs due to greater efficiency and lower standby losses; compliance with emission standards; multi-fuel capability; lower noise levels; reduced maintenance costs; improved crew comfort.

There is nothing wrong with steam technology, after all, most electricity is generated that way, and for railway use where power demand is very intermittent, one needs an energy storage system ie a large boiler, LNER style, with ample reservoir capability, between the conversion of chemical energy by combustion of the fuel, and its conversion to mechanical energy.

Internal combustion cannot do this and one needs a great big expensive diesel engine which is under-utilised most of the time. Internal combustion technology is inherently unsuitable for railways and has probably risen to dominance due to the relative neglect of steam technology until the mid-1970s and L D Porta. Chapelon did good work but got sidelined, and Cox and Ell in the UK was a last-ditch effort.

The take-over of internal combustion technology on the railways took place on the back of the automotive industry. But it does not belong on the railway, where size and weight are not the issue they are with road vehicles.

A model for elsewhere
The proposal could be a model for other railways on the continent that were electrified long ago when hydro-electric power was available at low cost. Nowadays, electricity has to be paid for at the going rate, which makes electrification less attractive on lightly used railways. There are many such where the electrification equipment is getting old and in need of renewal. Modern steam traction could be an option worth considering in these cases, in particular in conjunction with the use of renewable fuels such as forestry waste and other forms of biomass.

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