These new VECTOR average speed cameras are replacing "outdated wet film" Gatso speed cameras along the 50mph stretch of the northbound carriageway. A spokesman for the Highways Agency said: "Average speed check signage will be installed at the entry point to the enforced section and additional repeater 'camera' signs will be installed along the length of the enforced section to remind drivers".
April 2017 Update: Just thought you might like to be made aware that according to signage on the A3 the new average speed cameras now appear to be live.