Safe Speed Forums

These are cameras to enforce variable speed limits. At any indicated limits below 70, they will enforce at limit+10%+2mph, although realistically you'll be lucky to get anywhere near that speed.

There are various rumours that, when the limit is 70, the trigger is well above 79mph, but I wouldn't bet my licence on it. I certainly have it on good authority that, in the early days of the M25 variable limits, the trigger speed when the limit was set to 70 was around 92 mph.

In the early days of HADECS they were not approved for use in a 70mph speed limit; so much for your "good authority"!

HADECS
The Highways Agency Digital Enforcement Camera System (HADECS) is a digital enforcement product designed in the first instance to record violations of speed limits set via variable speed signs. As such it automatically adjusts its speed threshold to that appropriate for the displayed sign. Combining radar technology for speed detection and multiple cameras for image capture the camera outstation section of the equipment captures offence data and encrypts it to the standards specified by the UK HOSDB. This data is then automatically collected a number of times each day and saved to DVD in a secure police office by the HADECS instation.

The instation equipment additionally has functions for decrypting the evidence, displaying the offences and for performing the UK mandatory Secondary Speed Check. Offences that pass this test are then exported to be picked up by a back office processing system. Other functionality at the instation enables control of the camera outstations including enabling and disabling them, setting their speed thresholds, instigating the outstations to perform a self test and recovery of evidential and log data on demand. The instation is intuitive to use and includes a map interface to provide visualisation of the speed enforcement locations and their current status.

M25 Variable Speed Limit Enforcement

In 1995 the Highways Agency installed a variable speed limit system between junctions 10 and 16 of the M25 to encourage improved traffic flow along this stretch. Gantry-mounted speed cameras were installed by the Highways Agency to enforce the variable speed limit. Since 2000, the Metropolitan Police has been responsible for enforcement of the variable speed limit in Surrey (between junctions 10 and 15). Therefore these are not shown on our interactive map of core safety camera sites as these are not owned or operated by Surrey Safety Camera Partnership.