London Banter - View Single Post

Adrian · July 28th 08, 07:33 PM posted to uk.transport.london

(Neil Williams) gurgled happily, sounding
much like they were saying:

Perhaps he's suggestion that if we replaced double deckers with
articulated buses we'd have no such issues?

We probably wouldn't. But more sensible might be to require buses to be
constructed to be reasonably solid so that the top wouldn't be sliced
off quite like that. Of course, those sitting at the front wouldn't
have much fun quite simply because of the energies involved in such a
collision, but there's no reason why the entire top deck should collapse
like that in any properly-designed vehicle.

Umm, you'd prefer the bridge took more damage?

Because there's going to be plenty, it's just a question of where. You've
got 10t of vehicle, travelling forwards at c.20mph. That's a LOT of force
on a very small area - something's going to give.

Whatever happens, the front few rows of passengers aren't going to be
laughing and joking about it. If the top of the roof collapses
progressively, instead of just sliding back, then it's going to come down
as well as up. Oh, and they're chewing bridge, of course.

So the only real question is what happens further back on the top deck.
Look at the photo - there's no risk (other than by flying glass) to
anybody else on that deck from the roof sliding backwards - because it's
remained at fundamentally the same level. Yes, it's dropped down
slightly, as it's cantilevered backwards on the pillars, but that's not
going to do TOO much harm.

So - you reinforce the window pillars upstairs. A LOT. They're going to
have to transmit the forces backwards, else they'll just bend again, so
they'll have to be angled. That's going to put a LOT of force into the
rest of the bus structure, and almost certainly do significantly more
damage to the rest of the bus. I'd imagine it's fairly straightforward to
re-roof something such as that - but an impact of that force through a
structure designed to spread the forces and hold the roof on would very
probably write the entire body off. It's also got a good chance of
causing injuries downstairs as the structure there would collapse to
absorb the forces. Oh, and it'll add a metric ****load of weight to the
structure - already much lardier than the RM was - probably to Lardibus
weights. Which means much more fuel used, and more mechanical load, so
probably lower reliability - or the mechanicals would have to be beefed
up considerably.

Alternatively, perhaps the drivers could consider looking where the ****
they were going? I mean, it's not as if there isn't already a legislated
requirement for the vehicle height to be clearly marked in the driver's
view, and for low bridges to carry height warnings...