wrote in message
...
On Sat, 28 May 2011 17:20:08 +0100
"Paul Scott" wrote:

It helps to stop them hitting the platforms... :-)

Seriously though - they've been designed to be a best fit for the
infrastructure over the entire sub surface network, including those lines
where platforms are a compromise height because they are shared with tube
stock.

But none of the current sub surface stock seem to require it. In fact the
A stock actually goes outwards slightly. So whats difference about the S
stock?

Smaller wheels and a lower floor, so it cannot overhang the platform edge.

Paul S