On Oct 5, 10:18 pm, Dave Arquati wrote:
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.

Ah, now I understand - I thought that the A40 was already
grade-separated by the time the M40 was extended to its current
location.


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.

Indeed. Any such traffic would have to detour a long way south to reach
any decent road corridor.

Just out of curiosity, what sort of restricted traffic _would_ be
diverted away anyhow?


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).

There is also that - why did the legislation that created TfL leave out
the authority to manage a motorway anyhow?