Highways England has admitted that radar units used to detect stopped vehicles on smart motorways are too far apart, despite having previously placed an £18m order based on the existing spacing.
As a result, the cost of the contract, which covers the retrofitting of stopped vehicle detection (SVD) to existing schemes that were built without it, will increase by £7.75m to £25.75m.
Last year, the government-owned company issued the £18m contact to Navtech, whose SVD system was the subject of the trial and which was described by transport secretary Grant Shapps as the only supplier available.
However, Highways England has now issued a ‘modification notice’, which admits that although ‘the original scope and estimated value for the supply of SVD radar under this framework was determined based on the understanding that radar units would be sited on average 500 m apart’, following a review of the optimal spacing of radar, ‘units would be sited on average 300 metres apart in all future installations’.
The notice adds: ‘As a result of the decision, additional radar units and associated commissioning and support services have become necessary under this framework. The estimated value of the additional supplies and services is GBP 7.75 million.’
The extra work could have an impact on the completion of the retrofitting programme, which is currently due to be finished by the end of September 2022, however Highways England has said it is confident it can make this deadline.
It follows Highways’ exclusive disclosure that a 2016 trial of the system wrongly treated missed incidents of stopped vehicles as successful detections on the grounds that they were ‘out of range’ of the radar.
Highways England claimed that these incidents were beyond what was believed to be the range of the radar, even though they were within the 13km trial area.
The trial used 27 radar units, which was more than enough to space them every 500m, with each unit thought to be capable of detecting at a range of 250m in each direction.
It is not clear what Highways England will do about smart motorway schemes that already have SVD fitted, at what is now considered to be sub-optimal spacing. This includes schemes that have had SVD retrofitted.
In addition, Highways England is seeking a supplier for a separate contract, valued at £14m, to fit SVD to new schemes. This cost is also likely to increase as a result of the decision to increase the spacing.
David Bray, Highways England’s smart motorways project director, said: 'It is entirely inaccurate to claim that stopped vehicle detection radar are sited too far apart to be effective – the technology is effective as it is currently used. It is also inaccurate to suggest that the retrofitting of smart motorways could be delayed.
'The decision to place radar closer together is simply because it is more efficient to attach the units to existing infrastructure, rather than putting up new structures to hold them.'