On 19/12/2014 15:58, Jethro_uk wrote:
On Fri, 19 Dec 2014 15:36:57 +0000, Nightjar \"cpb\"@ wrote:

On 19/12/2014 14:34, Jethro_uk wrote:
...
TBH, it's hard not to get the impression that these 40/30/40 roads are
designed to rack up fines, since, with any more than a lone car, you
eventually wind up with the entire stretch going at 30 anyway. So you
may as well have had the whole road set to 30. Save metal and CO2
emissions. If that mattered.


It is a result of a DfT guideline that speed limits should not reduce by
more than 20mph in one step, so you get 60mph / 40mph / 30mph / 40mph /
60 mph and 70mph / 50mph / 30mph / 50mph / 70mph wherever that guideline
has been implemented.

Guideline, but not law clearly. Theres an NSL to 30mph transition a
couple of miles from me.


It requires a traffic order to change the limits, so there will still be
plenty of places where it has not yet been implemented.

--
Colin Bignell