Earl Purple wrote:
Dave Arquati wrote:

No, no, no, please, no, to all of that. They planned to do it some time
ago (http://www.btinternet.com/~roads/lon...ringway1.html).


I know about the planned ringway. I don't think they should go ahead
with the whole of that though.


Of course, the Westway was a roaring success for the residents of the
area it cut through.


Are you sure? Traffic has always headed into London from the West and
it would do so without the A40 and the elevated M4, probably on the A4
instead, so the Cromwell Road, with its museums and hotels would simply
be totally choked. And those who don't use the A4 would use the A4020
(much of which used to be the A40) passing through Ealing etc. even
though they have intention to go to Ealing, whilst conflicting with
local traffic.

I was talking about the effect on people who lived in the residential
area through which the Westway was constructed.

Nevertheless, yes, traffic heads into London from the West - but without
the Westway, less may have done so. Traffic congestion acts as a
restraining mechanism.

The Western Avenue and the elevated Westway should be considered
separately as I believe the Western Avenue was constructed somewhat
earlier than the elevated Westway.

The little bit of the West Cross Route that comes South off the A40 is
a fairly useless road - it's good down to Shepherds Bush then takes you
through residential roads that were never meant to be a highway. Going
Northbound, if you want to continue North you have to take A40 and A406
or work your way through the local areas of Harlesden and Neasden. Its
only real purpose is as a relief road for Wood Lane.

To be fair to it, it allows traffic to avoid Shepherd's Bush Green
(although, yes, it dumps the significant proportion onto Holland Road).

These urban motorways only serve to generate new car traffic

Maybe a little but most of it will just be diverted off other roads.
For example someone coming from Portsmouth heading North may well go up
the A3, onto this road and subsequently the M1 rather than using the
Western stretch of the M25. Certainly those who live in Kingston going
North are more likely to use it. But are these people going to
specifically make more journeys by car just because the road is there?

Yes. That's not really a point up for debate - research is available all
over the place proving that new roads generate significant levels of new
traffic. I doubt that someone coming from Portsmouth heading north would
divert from the M25 via inner west London, although M25 congestion might
force them to do so - which would be extremely bad for the residents of
West London, who would then have to put up with long-distance traffic
passing through their area (the motorway may be segregated, but the
pollution and noise wouldn't be).

The obvious example of traffic generation is the M25. Many people make
more journeys by car specifically because the M25 is there - it has
encouraged a vast number of orbital commutes which never existed before
it was built. An urban motorway, similarly, would encourage people to
make a car-based commute (or other journey) across inner London where
they wouldn't have done so before.

If they want to encourage more people to use trains then improve the
railways too.

Limited funds are available, and railway and motorway projects are both
extremely expensive. It's one or the other, and the project which
increases car journeys significantly is not likely to win. "They" should
definitely improve railway (and other public transport) connections -
but they shouldn't start building urban motorways.

(whether tunnelled or not), and are also incredibly expensive
particularly if tunnelled).

It's more expensive to build a tunnel than a bridge but it does mean
they don't have to buy up land and compulsory purchase orders may
obviously cost more.

Either way, it's very expensive, with new road costs now in the many
millions of pounds per kilometre.

Talking of cost though, do you know how much revenue is lost everyday
through traffic queues?

Firstly, since a new road will generate new traffic that surrounding
roads will have to absorb, a new road project is only likely to cut
traffic queues on certain parts of the network for a certain number of
years before the situation worsens again (see the M25 and associated
widening projects).

Secondly, when factoring in revenue lost through congestion, it's time
to start factoring in the increased cost of pollution-related illness
and disbenefits and road accidents, as well as the less-easily
quantifiable social exclusion and general environmental effects.

And actually, a road, if used properly, will usually take a greater
volume than a railway. On a D2 dual carriageway, for example, if cars
are travelling at a 2-second gap, you get 30 cars in each lane passing
per minute. If each car has 2 occupants, that's 120 passengers a minute
in each direction. You'd need to run a very frequent train service to
carry that many.

Other people are debating the truth in that, but, as always, junctions
often limit capacity on a network, and urban motorways will have plenty
of those. In addition, although a smaller point, it's worth noting that
the road capacity as described is only available to those with access to
a car, whereas rail capacity is (theoretically) available to all.

Anyway, they were supposed to be raising all this money to improve
roads through the congestion charge but all I've seen is totally
unnecessary roadworks on roads that aren't broken. But then we know Ken
is anti-car.

The congestion charge raises money to fund public transport
improvements, not the roads.

Which is thankfully why you'll
never see a grade-separated South Circular any time soon.

Do you live and drive in the South of London?

Nope... but I lived next to a motorway for 18 years, and I wouldn't wish
it upon anyone. I live in the west of London (which already has urban
motorways, one of which is extremely close to my home), but I don't
drive (and neither do a large number of people in this are) - and
therefore I get a rather disproportionate share of the disbenefits of
urban motorways compared to the benefits.

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London