TheOneKEA wrote:
Why does the M40 terminate so far outside London? A quick check of
aerial photos and a map shows that the A40 Western Avenue runs through
mostly open land between the M40 terminus and the A312 Church
Rd./Mandeville Rd. roundabout junction, with all of the junctions in
between fully grade-separated. With the M40 extended to the Church Rd.
junction, the A40 could be diverted along the path of the A4020,
running through Uxbridge and Hillingdon as far as the A312 roundabout,
where it could turn north and intersect the M40 at its new terminus.

Is there some particular reason why the M40 doesn't terminate closer in
to London? (i.e. the existing road needed to retain full access? NIMBY?
lack of money?)

The A40 was not totally grade-separated along that section until fairly
recently - the Master Brewer junction in Hillingdon was flat until a
bypass (and new Tube station) were built about ten years ago.

Aside from that, there are probably more disadvantages than advantages
to restricting access and changing all the signage and street furniture
(if necessary) along here. Whilst the M40 is a relative newcomer and has
an very obvious parallel unrestricted route (the A40), the Western
Avenue has been around for a long time (70 years?) and the unrestricted
alternatives would be rather awkward for local traffic.

The Western Avenue serves local traffic in a way that the M40 does not
(compare the 5kms between the M40's first two local junctions with the 1
or 2km spacing on the A40). The Western Av. is also now managed by TfL
as part of the TLRN, and it would be counter-intuitive to hand it over
to the Highways Agency when efforts have been made elsewhere to hand
roads from the HA to TfL (A102(M), A40(M), M41).

--
Dave Arquati
www.alwaystouchout.com - Transport projects in London