The cost of the Aberdeen bypass has risen to an estimated £653m.
The 28-mile road – previously predicted to cost £347m – was given the green light by Scottish ministers in 2009, but was delayed by legal action.
Protesters lost their appeal to the Supreme Court earlier this month.
Transport Minister Keith Brown said the “unwanted delays” had resulted in a “substantial increase” in the overall cost of the project.
It is anticipated that construction will get under way in 2014, with completion by spring 2018.
In answer to a parliamentary question lodged by Aberdeen Central SNP MSP Kevin Stewart, Brown said the scheme had been costed at £347m in 2008 – an estimate based on 2003 prices.
He said that the figure had now risen to £653m as a result of “scope changes, the inclusion of standard risk costs and rebasing to 2012 prices”.
Brown said inflation had been responsible for a £230m increase in the cost.
A scheme to make the A90 a dual carriageway between Balmedie and Tipperty in Aberdeenshire is also expected to cost £92m, giving a total of £745m for the combined project.