This may be a hoax, but basically this is the message I got in my inbox today......
~~~~~~~~~~~~~~~~~~~~~~~~~~
The new electronic signs on the M6 were switched on this Tuesday. The bad news is that they are rigged with the SPECS speed cameras. This probably applies to all the new signs being installed on the M62, M60 and M56.
SPECS is a computer-camera based system. As you go past the sign a digital camera reads your number plate. When you go past the next sign your number plate is read again. The computer 'knows' how far apart the signs are so it can work out your average speed between the two, or three or four. The system is fully automatic and will issue a ticket without any form of human intervention. It does this for every single vehicle that passes.
You will not know you have been caught as the cameras don't flash. They work 24/7, 365 days a year, and theoretically, there's absolutely no limit on the number of tickets that the system can issue.
The whole section of the M6 between Knutsford and Preston is wired, both ways. The system is set to trigger a ticket at 78MPH. (Don't take this as a guarantee) Radar detectors will be of no use as SPECS is entirely passive, there is no laser beam to detect.
<edit> Yes it is a hoax, WHY do I always fall for these things? </edit>
http://www.arseburgers.co.uk/blog/archives/000606.html