This would require dual-voltage trains with third-rail and overhead-wire capability.

Of course, railway stations require trains, and their new designs are almost as radical as the stations'.

The investment will require new trains and should result in reduced journeys times and a cheaper to maintain network.

Except for the Clayton Tunnel, the line was worked on the time-interval system, requiring trains on the same track to be separated by 5 minutes.

It will require separate trains for Heathrow passengers which cannot be justified by the comparatively small number of passengers involved.

At first each movement numbered less than 400 personnel but this soon increased to over 1 000 which required multiple special trains and additional steamer sailings.

Shaky ground had already caused concerns, requiring trains to be 'slowed' before crossing a nearby bridge.

Thousands of tourists came to see the ship every day, requiring special trains to accommodate them.

The service would not require new trains or tracks, but it is probably years away because it would pose complicated legal and technical problems.

This requires new signalling system, new trains and perhaps other minor efforts.