On Tue, 20 Dec 2011 01:02:03 -0800 (PST)
Neil Williams wrote:
OTOH, because the height clearance issue is the opposite way around
for rail, the UK doesn't do double-deckers on rail (the 4-DD excepted)
but they are very common in mainland Europe. Were the UK the main

Though even the euro double deckers (or at least the ones I've been on in
france) are really at the limit of practicality. The top deck is rather
low height and the curved sides impinge quite noticably. Its only really in
the USA that you get proper double deckers.

B2003