In message , Peter Masson
writes

It would be daft to develop Crossrail in the hope that adequate battery
technology would be available by the time the trains have to be
ordered. However, battery trains have been used for suburban rail -
Dublin to Bray between 1932 and 1950. In .uk a battery MU operated
between Aberdeen and Ballater in the early 1960s, while battery locos
have been used to haul engineering trains on LU in the dead of night
when the power's een switched off.

Although I agree with the basic premise, battery technology is becoming
increasingly impressive - parts of the new Rome trolleybus system
currently run on battery power for some miles, and Alstom's trams for
Nice also run on batteries in the city centre. These are vehicles
capable of carrying a large number of passengers in heavy traffic,
although probably not on the scale required for the far reaches of
Crossrail.
--
Paul Terry