måndag 8 januari 2007

New trains for the London Underground




Artist's impressions of the next generation of trains for London Underground have been released by Metronet. The quality of these computer-generated images is amazing. The trains will be built by the international company Bombardier.

The front ends look highly styled and a long way from the the functional elegance of the Frank Pick era. The surface line stock front ends especially look like shower cabinets for the flashy-end of the market. Is this really how Transport for London wants to present itself?

More importantly, is it the most practical solution?
The function of the cab assembly is
(1) to protect the driver against possible collision damage
(2) allow the driver a good view of the signals and CCTV monitors,
whilst protecting against thermal gain from the sun, missiles and
other flying objects.
(3) provide a surface for the mounting of information eg marker lights
and route indication displays.

What is shown does not spell out this function particularly clearly, rather it seems to have been designed for forecourt appeal. But then I am a mid-twentieth century functionalist fogey, so I am probably missing the point.

However, there is are issues regarding large curved windscreens. Since the 1960s, LUL tube trains have long had curved windscreens, but it is easier and less expensive to make toughened glass flat and it is also easier to source replacements over the lifetime of the vehicles if the glass is flat and not handed (ie you do not need left hand and right hand versions).

And of course less spares then have to be held in store, so there is another saving. It was the fate of a lot of BR stock to have curved wndscreens replaced by flat. There is also the advantage that flat glass does not cause optical distortion. Also, large windows tend to cook the driver, as was found with Networkers which had to have an upgrade to the cab ventilation system.

The surface line stock has lower bodyside curvature. In this it differs from previous LUL stock which has vertical sides from solebar to the bottom of the window. A BR gauging engineer once told me that there is no reason for having lower bodyside curvature from 925 mm above rail level (the height of a station platform), other than as a styling feature.

Presumably the same applies to LUL routes - actually the A60/A62 Metropolitan Line stock is 9ft 6in wide all the way down to the floor (wider than BR stock).

New Electrostar stock on Southern and elsewhere demonstrated the problem caused by the pronounced lower bodyside curvature which reduces the width at floor level. This appears to be nothing more than a styling feature. The problem is aggravated by the presence of skirting level ducts. This means that passengers occupying the transverse seats next to the windows only have space to put one foot on the floor unless they sit in a twisted position!

A single type of stock for all surface lines is proposed. But although a single bodyshell design is probably practicable and desirable, how can one seating configuration will be suitable for both Circle Line and Uxbridge/Amersham line services? There also appears to be too much space between handholds - it is essential to of plenty of things to hold on to, and I wonder if the need to provide circulation space for wheelchairs is not creating a hazard for other passengers, especially the elderly.

Either you will end up with too many people having to stand for a long journey, or not enough circulation/standing space in the central area.

The new trains will be air conditioned. Nice, and these days it is at last reliable. but I hope someone has calculated the heat emission from air conditioning and is satisfied that it can be dispersed.

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