There are fears that someone will be killed as sat navs are sending people the wrong way up the A30 at Scorrier.
Despite a raft of road signs drivers are risking a serious accident by following sat-navs directing them the wrong way down a dual carriageway slip road.
Signs telling drivers to ignore their sat navs have been placed at the new roundabout and one-way system at Scorrier, near Redruth.
According to Scorrier councillor Mark Kaczmarek drivers were ignoring as many as nine signs warning of the new system and driving down a one-way slipway in the wrong direction.
Mr Kaczmarek said a nearby pub landlord counted 100 vehicles turning around on the slip road, including large trucks. With some turning round only a hundred yards from the blind exit slip from the busy main road
He adde that with traffic is coming off the A30 and on to the slip way at around 70 miles an hour, there are concerns of a serious accident.
Peter Tatlow, a senior engineer with Cormac, said: "If people are not looking at the signs, it's difficult to know what to do.
"It's a real worry that someone is going to miss the 'no entry' sign as well."