MOTORISTS face a decade of disruption after ministers announced the £3 billion of work to make Scotland's most dangerous road safer will start two years earlier than expected.

Despite its new starting date of 2015/16, the project to upgrade the A9 to a dual carriageway from Perth to Inverness is not expected to finish any earlier, but supporters of the scheme said it will revolutionise the backbone of Scotland's road network once completed.

A total of 67 people died and there were 1206 accidents involving injuries from 2006 to 2010 on the A9.

The work will convert 80 miles and seven sections of single carriageway, with the previous A9 Kincraig to Dalraddy overtaking-lane scheme south of Aviemore to be extended to a full dualling project. The work is predicted to be a major catalyst for growth in Inverness and the north, bringing real benefits for Scotland's tourism industry.

Alex Neil, Cabinet Secretary for Infrastructure and Capital Investment, said: "The A9 is the longest trunk road in Scotland and we have always said that delivery by 2025 was challenging but achievable. I'm especially delighted to announce we are advancing the Kincraig-Dalraddy section to full dualling and doing so early."

He said the sheer scale of the A9 project was enormous, describing it as "16 times the length of the completed M74 and eight times the length of the M80 between Stepps and Haggs".

He added: "In the immediate future, we will continue to invest in short and medium-term improvements on the A9 in anticipation of dualling ."

Chief Secretary to the Treasury Danny Alexander, whose home is close to the road which runs through his Inverness, Nairn, Badenoch and Strathspey constituency, said: "While I cautiously welcome the news that the SNP are, at last, taking the dualling of the A9 seriously, the work announced this week will not start until the end of this government's term of office; and the project is not due to be completed until 2025. It is imperative that we keep the pressure on the Scottish Government to see this project through in good time."

Drew Hendry, SNP leader of The Highland Council, added: "Upgrading of the A9 is critical to the wellbeing both to our people and to the economy of the Highlands."

Campaigners have long called for major improvements to the A9 between Perth and Inverness. Two men were killed in a crash earlier this month at Ralia in the Highlands. Another crash this month killed two lorry drivers near Blair Atholl in Perthshire.

Richard Baker Scottish Labour's Shadow Cabinet Secretary for Infrastructure and Capital Investment, said: "Alex Neil's photo opportunity today is simply re-announcing what we already knew."

Meanwhile Mid-Scotland & Fife Conservative MSP Murdo Fraser, a long-time campaigner for the upgrade said: "I warmly welcome any announcement regarding upgrades to the A9."

Neil Greig, director of policy and research at the Institute of Advanced Motoring, said "Obviously there is going to be a lot of disruption over a 10-year period, but it is a price worth paying. Dualling the road means you get rid of most of the frustrated overtaking problems that account for many of the deaths of the A9."