Brimstone wrote:
sharky wrote:
Looking at those pictures, the top of the tunnel seems to be very
flat,
even on the 'before' pictures.
I thought a tunnel/bridge needed to be arch shaped to support load
above - those seem to be two right angle bends with a flat section
across the
top - surely obviuosly not right.
Perhaps the sides were two wide apart, leaving and unnaturaly flat
meeting point?

Take a look at the Maidenhead bridge arches.

Yes. Arches can be quite flat, as long as there is emough support
either side to stop them spreading. Hence flying buttresses.

Colin McKenzie