The full outgo of upgrading a six mile (10km) conception of the A9 successful the Highlands is present expected to tally to £308m - £111m much than primitively estimated, according to a Scottish authorities report.
The Tomatin to Moy stretch, southbound of Inverness, is 1 of six projects to upgrade of the trunk roadworthy from Inverness to Perth to dual carriageway by the extremity of 2035.
The study connected large infrastructure projects said an archetypal estimated full outgo of £197m aboriginal roseate to £254m and past successful July this twelvemonth to £308m.
SNP Inverness and Nairn MSP Fergus Ewing said a "full explanation" was needed of wherefore the full outgo was not mentioned successful a caller Scottish authorities announcement. Transport Scotland has been approached for comment.
Two sections of azygous carriageway totalling 11 miles (18km) of roadworthy person been upgraded implicit the past decennary nether the £3bn dualling project.
But 77 miles (124km) of the way has inactive to beryllium dualled.
When completed, the caller Tomatin to Moy conception would supply astir 20 miles (33km) of continuous dual carriageway betwixt Inverness and Slochd.
The task has been deed by delays, including earlier this month erstwhile it was revealed the conception was expected to beryllium operational successful 2028 and not precocious 2027 arsenic hoped.
Last year, the operation declaration was re-tendered aft lone 1 institution bid for the work.
In July, the Scottish authorities bureau awarded the declaration worthy astir £185m to Balfour Beatty Civil Engineering Ltd.
The caller study said ostentation and costs astir a alteration successful declaration procurement had led to the accrued estimated full outgo of £308m.
Mr Ewing said the Scottish authorities "needed to beryllium candid" with the nationalist connected costs.
He told BBC Scotland News: "A afloat mentation is needed to accidental wherefore the full costs were not mentioned successful the caller property release.
"The full outgo will, I expect, see each preparatory enactment successful way selection, and design, obtaining the indispensable ineligible orders."
Mr Ewing added: "But until specified clip arsenic the full concern lawsuit figures are breached down into components and made public, we stay successful the dark."
Scottish Conservative MSP Jamie Halcro said nonaccomplishment to dual the A9 erstwhile promised to had led to the outgo "skyrocketing" owed to inflationary pressures.
He said: "The nationalists’ breached promises mean taxpayers volition request to ammunition retired millions more, not conscionable connected the Tomatin-Moy conception but doubtless connected each different stretches too."
Expected operational dates of the different remaining sections nether the caller programme, taxable to declaration and backing processes, according to the A9 dualling task are:
- Tay Crossing to Ballinluig - by the extremity of 2028
- Pitlochry to Killiecrankie - by the extremity of 2030
- Pass of Birnam to Tay Crossing - by the extremity of 2032
- A9 North, comprising the Crubenmore to Kincraig and Dalraddy to Slochd projects - by extremity of 2033 astatine earliest
- A9 Central, comprising the Killiecrankie to Glen Garry, Glen Garry to Dalwhinnie and Dalwhinne to Crubenmore projects - by extremity of 2035 astatine earliest
The study besides provides updates connected different projects.
It said electrification of the Borders obstruction enactment and of the Fife Circle obstruction enactment had been paused owed to an ongoing "refresh" of a decarbonisation enactment plan.
A unafraid wellness portion for young radical successful Ayrshire, owed to beryllium opened by the extremity of past year, was inactive not implicit and a caller National Treatment Centre being added to Forth Valley Hospital had been further delayed owed to operation problems.