HADECS

HADECS or Highways Agency Digital Enforcement Camera System is a type of speed camera on roads in England, operated by Highways England.
History.
The HADECS camera was introduced in 2012. 
HADECS cameras have been introduced to enforce variable speed limits (VSLs) as found commonly on managed motorways - hard shoulder running in peak traffic flows.
Hadecs 3.
Hadecs 3 was introduced on the M25 in Kent in April 2014, becoming active on 22 October 2014.
Two manufacturers currently hold HOTA to supply equipment for the HADECS 3 system, those being Redflex Holdings and Dynniq.