The original price tag for the proposed new road linking north west Preston with the M55 was £104m.
But it emerged early last year that the cost of the so-called Preston Western Distributor route had rocketed to £161m.
READ MORE >>> All you need to know about the new Preston-M55 link road
The price soared partly as a result of investigation work which revealed that two aqueducts needed to be re-routed - one of which was complicated by poor ground conditions along its length.
It is expected that just under half of the bill for the road will be footed by the Preston, South Ribble and Lancashire City Deal, with Lancashire Growth Deal funding contributing £58m and £25m coming from the government for construction of the new motorway junction.
A meeting of the City Deal board last month heard that the scheme had a risk-rating of "amber" - largely because of concerns over the outcome of two legal challenges to the route. Both of those hurdles have now been overcome.
The government has today given the go ahead to the construction of the road, following a public inquiry into the issuing of compulsory purchase orders for the land on which it will be built. Last month, it emerged that a separate legal challenge about the proposed entrance to a new garden village to be accessed via the road had been dropped.