On Wed, 2 Mar 2011 22:34:44 +0000
Tom Anderson wrote:
Specifically, i think it's that there isn't room for a double track
bearing freight trains with overhead. Freight trains being taller than
passenger trains (passenger trains all fit in W6A in this country, i
believe; squinting at a map from 2004, it looks like the Canonbury curve
might be W9).

I don't think its the height so much as the profile. Passenger trains
curve in towards the top whereas container freight wagons are a box shape
which tend not to work in tunnels where the curved roof would cut in on
the boxy corners.

B2003