Vital safety upgrades designed to spot broken-down vehicles were not yet operational when a driver died in a smash on the M1 near Northampton, National Highways has confirmed.
Stranded Vehicle Detection (SVD) radar systems are being retro-fitted to all the UK's existing Smart motorways where hard shoulders have been converted into 'live' lanes.
But the rollout, ordered following safety reviews in March 2020, is not due to be completed until September.
One man was killed and four passengers were injured in a fatal collision near junction 17 on Monday (July 18).
Crash investigators from Northamptonshire Police believe the victim, a man in his 40s from Bedfordshire, was standing behind a stalled Mercedes in lane one when it was in collision with a Toyota Previa at 3.20am.
A spokesman for the force said its investigations are continuing so that officers can prepare a report for the coroner, adding: "We would still like to hear from anyone who believes they may have information which could assist us and would ask them to get in touch by calling 101."
National Highways, which runs England’s major road network, says it is on track to meet the target of having SVD technology in place on every existing all lane running smart motorway by the end of September.
A spokesman added that SVD units have been installed on the Northamptonshire stretch and the system is “in the process of being commissioned”.
National Highways head of service delivery, Andrew Butterfield, said: “Every road death is a tragedy and our thoughts are with all those affected by this incident.
“At this early stage, while it is being investigated it would not be appropriate for us to comment on the circumstances or the cause.”
Work to turn a 16-mile section of the M1 between junction 16 and 19 into an 'all lane running' motorway was finished in 2018 as part of a national programme to tackle congestion on Britain’s roads.
Hard shoulders are removed and replaced by an extra traffic lane with safety refuges at regular intervals, about a mile apart, for vehicles to stop if drivers experience a problem.
But safety concerns prompted a review in March 2020 which ordered National Highways to add SVD technology to more than 200 miles of all lane running motorway by September 2022 and upgrade enforcement cameras to detect vehicles ignoring Red X cameras over closed lanes.
National Highways claims that SVD identifies stopped vehicles, typically within 20 seconds, allowing operators to activate signals shutting lanes, display speed limits and deploy traffic officers.
The Department for Transport and National Highways say that smart motorways are, mile-for-mile, safer than conventional motorways.
Another 23-miles of Smart motorway between Northampton and Milton Keynes is planned to open next year despite indications it would be delayed for five years while more safety data is gathered.
Ministers announced a pause in all “future schemes” but later confirmed the stretch between junction 13 to junction 15 will open as planned in 2023 — with SVD in place — because it was already more than halfway towards being finished.