fredag 18 maj 2018

Minding the gap

Gaps between platforms and trains are another problem caused when there is a mis-match between the infrastructure and the trains. When the system was built in the early days of Queen Victoria, passenger carriages were short four-wheeled vehicles, typically less than 10 metres long. Over the next century, the standard length of a British passenger vehicle had risen to 20 metres. With bogies close to the ends, and about 14 metres apart, there would be a large gap on sharply curved concave platforms. This was not usually a problem with slam-door trains as passengers would lower the window inside the door and use the top of the window frame for support when getting on and off. The trains were also fitted with external handrails. This was not an ideal arrangement but it worked.

The first large scale use of sliding door trains on the national system adopted the 1/3:2/3 configuration, as in these class 313 trains seen here at Brighton. The size of the gap is obvious. From the mid-1980s, this 1:3:2/3 configuration became standard for all trains in Britain apart from the inter-city fleet, where end doors became the standard. The final BR designs, however, adopted a 1/4:3/4 configuration, with two seating bays between the vehicle ends and the doorway vestibule.  This was a feature of the Networker and derivatives of the design including the 20 metre Electrostar classes. This reduced the size of the gap because the doorway was only just inside the bogie wheelbase. The 23 metre Turbostars were similar, but with five bays instead of four between the doorways.

The new CAF Civity trains for Northern seem to have reintroduced the problem, as these are 23 metre vehicles with the doorways three bays in from the ends, and four bays between the doorways. As the photograph shows, the doorways are well inside the bogie wheelbase, which could give rise to large gaps at concave platform faces. We shall see.

The problem could of course be solved entirely if the trains were fitted with retractable steps, but that is a step too far, it appears.

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