The D-train is a project to recycle the London Underground's District Line D78 stock, introduced in 1978. It was heavily refurbished between 2000 and 2003 with new bogies and other equipment. It is basically in sound condition and good until at least 2025, but it was decided to replace it with the S-stock to provide London Underground surface lines with, for the first time, a uniform fleet.
This will in due course almost certainly prove to have been a bad strategy for London. Railway rolling stock tends to suffer from some weaknesses which show up almost immediately, and others which show up after a decade or two, in both cases affecting the entire fleet. The thirty Bulleid-designed Merchant Navy class all had to be taken out of service and eventually rebuilt, following an incident in 1953 which revealed a fundamental failure with the design. A similar thing happened with the thirty GWR King class locomotives after it had been in service for almost thirty years. It would be good luck if the entire fleet of S-stock is not eventually affected by some defect which means that it will all have to be taken out of service for remedial action.
But to return to the D78 stock. Adrian Shooter saw the opportunity to recycle this stock for secondary services on the national system. In principle that was a shrewd move, though easier said than done, because the trains are electrically powered and the intention is to operate them on lines which are not electrified. The chosen approach was to install underfloor engines to power generators to drive the trains' existing electric motors.
This might have sounded like an economical solution, but fitting generators under the floor of a train can be tricky; the weight of the equipment is one difficulty and the lack of space another.
And so it has proved. The initial use of the trains, now designated class 230, was intended to be between Nuneaton and Coventry. However, an engine caught fire on the trial run and the backers have pulled out of the project.
That seems like a precipitate decision, but the project, it is claimed, has now been delayed to the point that it could not meet the timetable set for development.
One has to wonder about the thinking that lay behind the notion. Putting the generator in a separate and reasonably spacious compartment would have been easier and less likely to run into trouble. Using the carriages as locomotive-powered push-pull sets would have been even less risky, and more flexible too, especially if the locomotives used in the trial had been of a well-established type such as the class 20 or 37, of which a number are still serviceable.
Then there is this, specifically designed for secondary routes, within the constraints of the contemporary railway environment. It is nearly eight years since the developer, DLM-AG of Winterthur, came up with the proposal. The firm has so far failed to find sufficient interest for the minimum build of twenty units, costing around £30 million in total, which would be necessary to achieve a favourable price, around 30% of that of a comparable diesel locomotive.
