Cornwall's most notorious stretch of road is to be widened into a dual carriageway next year.
If approved, the dualling would include the notorious Iron Bridge
The government has finally confirmed that work to dual the A30 in central Cornwall will begin in January.
The plan involves building a new dual carriageway north of the existing single carriageway, avoiding Goss Moor.
But some environmentalists have criticised the £69m scheme, saying it could wipe out rare species of flora and fauna.
The dualling will bypass a single lane stretch of the road on Goss Moor which connects two dualled sections. Traffic jams on the single lane can last for hours.
The plans will ease congestion around the Iron Bridge - which is a notorious accident blackspot.
Transport Minister David Jamieson said: "The A30 is a strategically important route for all of Cornwall and vital for the county's economic future.
"In particular, this scheme will provide improved access to central and west Cornwall in the interests of economic development and tourism. It will also make journeys more reliable for motorists."
However, Goss Moor is an important nature reserve and many environmentalists fear an adverse impact on wildlife.
Mr Jamieson said: "The road as it is at the moment is not good news for the environment because a lot of the time traffic is at a standstill, causing pollution.
"There's also the hazard of the bridge and the accidents that have occurred there."
It is expected to take two years to complete the scheme.