DRIVERS face ten years of continuous traffic disruption when a massive project to upgrade the A9 starts next year, experts have warned.
The £3 billion scheme to build 80 miles of dual carriageway between Perth and Inverness begins in the summer and is due to be completed in 2025.
The Scottish Government’s Transport Scotland agency has described it as the most expensive transport project in the country’s history.
Motoring groups said building will have to take place on more than one of the 12 work sections at once to get the job finished on time.
Construction is likely to be accompanied by reduced speed limits – 40mph or lower – following past practice.
Transport Scotland said any lower limits are expected to be enforced using average speed cameras, which go live on the single carriageway sections involved on Tuesday.
Motoring groups said contraflows were also likely, but project managers will seek to avoid having to use traffic lights because of the importance of Scotland’s main north-south route.
However, road builders will have limited flexibility in keeping construction work away from traffic because ministers have agreed to keep it within a 200-yard corridor around the existing road to limit the environmental impact.
Neil Greig, the Scotland-based policy and research director of the Institute of Advanced Motorists, said: “There will inevitably be delays, but they will need to keep the traffic moving.”
Greig also expressed concern that drivers could be confused by the use of the cameras to enforce speed limits through the roadworks if they were lower than on other stretches.
He said: “The authorities will have to be very clear how they will work.”
AA president Edmund King said: “A week might be a long time in politics, but a decade is a heck of a long time to be in roadworks on the A9.
“Obviously drivers in Scotland will want to see these vital road improvements speeded up as much as possible.
“We would press for the most dangerous sections of road to be a priority and also make the case for the level of traffic disruption to be kept to a minimum.
“Unfortunately, when it comes to road widening there is no gain without some pain.”
Transport minister Keith Brown last week announced a shortlist of four bidders competing to build the next dual carriageway section: five miles between Kincraig and Dalraddy, south of Aviemore.
Three further sections are due to start in 2017.
Brown said: “We expect to put the first spade in the ground next summer, some six months earlier than originally planned.”
The Civil Engineering Contractors Association (Scotland) backed lower speed limits enforced by the cameras through the roadworks.
Chief executive Alan Watt said: “They protect the workforce and lead to a better flow of traffic, including on temporary surfaces. We would very much support Transport Scotland if it did that.”
A Transport Scotland spokesman said: “It is too early to provide details on proposals for traffic management around the A9 dualling programme.