On Sat, 4 Aug 2012 14:19:06 +0100, "tim....."
wrote:

There is already a section around Brum that does that. Part of the M42
IIRC, I drove on it last week,

That was the original pilot scheme from 2006, which was deemed to be
very successful, so the idea is being rolled out more widely. It's
already operational on the M6, with the M1 under construction and many
more to come.
See http://www.highways.gov.uk/news/25754.aspx