"Tom Anderson" wrote in message
rth.li...
On Wed, 1 Dec 2010, d wrote:
Can someone explaimn the fuss about bimodes? The french have had them
for a while and they seem to work ok.
It'd mean diesel-engined trains running under the wires *all the time*,
and you know how upset the ukr chaps get about that!
The much debated problem was the DfT specified 10 car bi-mode, which was
believed to be badly underpowered either under the wires, or off the wires.
Roger Ford of Modern Railways argued that the diesel would be needed most of
the time when under wires, DfT apparently had a different understanding (or
a completely different set of Newton's laws of motion maybe) and reckoned
the diesel would be needed only occasionally for a quick boost.
The 5 car bi-mode IEP, OTOH, had adequate installed power in either electric
or diesel power, but wasted a complete driving car, so would have little or
no capacity improvement over the dreaded Voyager.
The French unit quoted by 'boltar' is a relatively low speed local E/DMU,
IIRC it has a diesel generator in a partitioned off area in one of the
passenger areas, with a gangway past it - easy enough in their larger gauge
trains maybe? I don't think anyone's denied that it works, but would it
scale up to a 125 mph intercity train at UK dimensions?
Paul S