On Mon, 13 Oct 2008, Colin McKenzie wrote:

John B wrote:
On 11 Oct, 20:02, wrote:
But a new conventional 225km/h line to Manchester might be enough,
offering about 1h45, and the same argument could apply elsewhere.
Maybe only the Scottish run really needs more. Britain is smaller than
France or Spain, and thus the gains to be achieved from building LGVs
are proportionately less, particularly within England alone.

I'd be interested to see any studies on the cost per km of a new 225km/
h line versus the cost of a new LGV - and rather surprised if they
were significantly different.

The other issue no-one has mentioned is the cost (amount of energy) used per
mile of high speed rail travel compared to medium speed. With efficient
regenerative braking, most of the energy used is to overcome friction, which
rises with the square of speed - i.e. up to twice as much energy is needed to
go at 200 mph compared to 140 mph. This matters because the main reason for
preferring rail to air is reduced CO2 emissions.

Even if you did double the energy use, grams of CO2 per
passenger-kilometre is still quite a lot lower for a train than a plane.

According to this random and doubtless highly reliable document i just
found on the internet:

http://www.campaigncc.org/Howdoesairtravel.doc

The numbers for a London - Edinburgh trip are, in grams of CO2 per km:

car: 129
train: 73
plane: 339

A while ago, i found an EU report which had much more detailed and
reliable numbers for a variety of transport modes, mostly from a freight
point of view. They were similar to the above, but what was striking was
that ships (as in vast container ships) were about an order of magnitude
more efficient than the next best thing. Not so hot for moving passengers,
of course.

Admittedly it's easier to power trains than planes from non-fossil fuel,
but it's going to take a long time to get all our electricity from
renewable or nuclear sources.

True. Part of the TGV equation in France, i have been led to believe, is
the ready availability of fairly cheap and reliable nuclear power. They
are probably now feeling quite smug about the CO2 implications of this
too.

I think 140 or 150 mph rail is fast enough for the UK. But that needs to
cover a lot more than a few principal routes, so that overall journey
time is not clobbered by 20 or 30 slow miles at each end.

The other factor in overall journey time is frequency - it's not much
use getting to Edinburgh in 2 hours if you have to wait another 2 hours
for the train to leave. That means we need increases in rail capacity as
well as line speed.

Yes to both of these. The 'enemy' isn't the plane, it's the car, which
accounts for a much bigger share of our CO2 output. A few high-speed
long-distance routes won't attract much modal share from cars; for that,
we need more capacity and reliability on existing routes, and to restore
and build more local routes where they're currently missing.

tom

--
Baby got a masterplan. A foolproof masterplan.