"Mr Thant" wrote in message
...
On 19 Apr, 11:30, "Peter Smyth" wrote:
It sounds like an April Fools joke but apparently TfL are considering
it.http://tinyurl.com/5augle

Presumably if this were to go ahead the line would have to be closed
for
an extended period.

It refers to AC motors, which are more efficient than DC motors. AC
motors are driven by chopping up DC power electronically to match the
desired rotation speed, so there's no need to have the traction
current be AC. The Jubilee and Northern stock already has AC motors,
as do Networkers and most if not all newer EMUs.

Thanks - it makes a lot more sense now.

Peter Smyth