M25 J5-J7 speed test - latest info
Discussion
I managed to get the following info out of the press office of National Highways which may be useful for those using this section of the M25.
Although much of the traffic management typically associated with roadworks was fully removed on 28 March 2025 and the carriageways went back to four running lanes, but we’ve maintained a 50mph speed restrictions as a safety measure, whilst we carry out the testing of the new technology and upgraded Stopped Vehicle Detection (SVD) system.
Upgrading the stopped vehicle detection is a separate piece of work to building the new emergency areas: we've been delivering the projects side-by-side to minimise disruption. Where the 50mph speed limit remains in place after the other roadworks have been removed the new emergency areas are all open and available for use.
The testing work isn’t visible from the roadside. Perceptions might be that there isn’t any justifiable reason for reduced speeds being displayed, however this isn’t the case, and it’s needed until these tests are complete. We rigorously test our Stopped Vehicle Detection systems before they go live to ensure they meet our high-performance specification. This can only happen when there are no roadworks and when drivers are able to use all lanes of the motorway.
This includes:
• Recording the road layout in the SVD system (a process that can only be completed once roadworks have been removed)
• Training the radar that the SVD system is based on to reliably spot stopped vehicles and not create false alarms for reflections, signage, and other factors
Toward the end of this testing period, we check the system’s its real-life performance by using overnight closures to stop one of our site vehicles on the edge of the radar coverage area to make sure it’s detected, and its location is correctly reported to the National Highways Control room.
The testing of the SVD is being monitored 24/7 and final commissioning is needed to get the technology performing in line with our high specification for the system, enabling National Highways to close lanes, set signs and get help on the way as quickly as possible.
When we can remove the speed limit is determined by when the newly installed system is performing to our specification, rather than a strict timescale. Normal operations (variable mandatory speed limits up to the national speed limit) will be reinstated once the tests are complete. We expect this to be before the end of May 2025 but are working hard to improve on this.
We know that this is frustrating, but we would like to reassure you that we’ll remove the temporary speed limits as soon as the testing has been completed.
Please can I take this opportunity to thank you again for contacting us and again we apologise for any inconvenience these works may have had on you. You can find out more about our National Emergency Area Retrofit programme here: National emergency area retrofit - National Highways.
Although much of the traffic management typically associated with roadworks was fully removed on 28 March 2025 and the carriageways went back to four running lanes, but we’ve maintained a 50mph speed restrictions as a safety measure, whilst we carry out the testing of the new technology and upgraded Stopped Vehicle Detection (SVD) system.
Upgrading the stopped vehicle detection is a separate piece of work to building the new emergency areas: we've been delivering the projects side-by-side to minimise disruption. Where the 50mph speed limit remains in place after the other roadworks have been removed the new emergency areas are all open and available for use.
The testing work isn’t visible from the roadside. Perceptions might be that there isn’t any justifiable reason for reduced speeds being displayed, however this isn’t the case, and it’s needed until these tests are complete. We rigorously test our Stopped Vehicle Detection systems before they go live to ensure they meet our high-performance specification. This can only happen when there are no roadworks and when drivers are able to use all lanes of the motorway.
This includes:
• Recording the road layout in the SVD system (a process that can only be completed once roadworks have been removed)
• Training the radar that the SVD system is based on to reliably spot stopped vehicles and not create false alarms for reflections, signage, and other factors
Toward the end of this testing period, we check the system’s its real-life performance by using overnight closures to stop one of our site vehicles on the edge of the radar coverage area to make sure it’s detected, and its location is correctly reported to the National Highways Control room.
The testing of the SVD is being monitored 24/7 and final commissioning is needed to get the technology performing in line with our high specification for the system, enabling National Highways to close lanes, set signs and get help on the way as quickly as possible.
When we can remove the speed limit is determined by when the newly installed system is performing to our specification, rather than a strict timescale. Normal operations (variable mandatory speed limits up to the national speed limit) will be reinstated once the tests are complete. We expect this to be before the end of May 2025 but are working hard to improve on this.
We know that this is frustrating, but we would like to reassure you that we’ll remove the temporary speed limits as soon as the testing has been completed.
Please can I take this opportunity to thank you again for contacting us and again we apologise for any inconvenience these works may have had on you. You can find out more about our National Emergency Area Retrofit programme here: National emergency area retrofit - National Highways.
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