Police and the Department of Transport have improved the signage on the Mountain Road, to reinforce the message that the route is one-way.
It follows reports of several vehicles going against the flow, endangering their own and other people's lives.
Inspector Richard Power from the Roads Policing Unit believes it was already quite clear the road was one-way, and is repeating a plea to motorists to drive and ride with care as practice week comes to an end.
He says it's been a testing time for officers over the past couple of days, with one fatal and one very serious accident, as well as several minor incidents to deal with.
Inspector Power wants people to take notice: