On Sun, 30 Dec 2007, asdf wrote:

On Sat, 29 Dec 2007 18:00:13 +0000, Tom Anderson wrote:

The clever bit about the Bakerloo tunnel is that it allows trains that
would otherwise have to reverse at Queen's Park to go somewhere; if the
plan to reorganise the DC lines comes to pass, so that all Bakerloo
trains can go beyond Queen's Park, with NR trains (from the Overground)
terminating there, this becomes a less good plan.

Possibly-ignorant question: why can't some Bakerloo trains go beyond
Queen's Park? I looked on the interweb but couldn't find anything about
some trains being different to others.

Sorry, i phrased that badly. All Bakerloo trains are, as far as i'm aware,
capable of going beyond Queen's Park - it's just that some don't currently
have the opportunity to do it, because north of there, the track is also
used by suburban trains from Euston (QP being where the Bakerloo tunnels
and Euston surface tracks join up), so there isn't enough capacity (AIUI).

There's only 3tph from Euston north of Queens Park, but many more
Bakerloo trains than that terminate at QP.

I think the main reason is simply that the outer part of the line
doesn't require as high-frequency a service as the central part.

There's also the fact that the Euston trains are running to a stricter
timetable than the Bakerloos, as they're only 4tph, and that combination
seems to be very hard to make work at high density. Effectively, you need
to leave big enough gaps in the Bakerloo service that if it drifts a few
minutes ahead of or behind itself, it doesn't clobber the Euston service.

No doubt the lack of demand is the main reason, though.

It's interesting that the arrangement here is the reverse of the normal
situation - instead of one central route with two outer branches, there
are two routes from the centre combining to form one outer branch. I'd
say the clever bit about the Bakerloo tunnel is that it would re-balance
the situation (especially with the District currently having too many
western branches).

Also true. It does mean that whatever branch gets taken over has to take
an indirect route into town, though; it's a shame there isn't another
existing radial route in that area that could receive the blessing of the
little brown trains!

tom

--
We had two bags of grass, seventy-five pellets of mescaline, five sheets
of high powered blotter acid, a salt shaker half full of cocaine, and a
whole galaxy of multi colored uppers, downers, screamers, laughers... and
also a quart of tequila, a quart of rum, a case of beer, a pint of raw
ether and two dozen amyls. Not that we needed all this for the trip,
but once you get locked in a serious drug collection, the tendency is
to push it as far as you can. -- Hunter S. Thompson, 'Fear and loathing
in Las Vegas'