A contraflow system is where traffic is directed in the opposite direction than it would normally flow. The clue is in the name with “contra” meaning against and “flow” meaning the movement of traffic. You'll often find temporary contraflow systems when there's roadworks, but they can also be permanent.

What happens in a contraflow system?

A contraflow system means that traffic will be flowing along lanes in the opposite direction to the norm. As such, when you approach a contraflow system you should reduce your speed in plenty of time. ... You should also stay in your lane and avoid making attempts to overtake whilst driving on a contraflow system.

What is the purpose of a contraflow system?

Contraflow is a method designed to increase the capacity of transportation roads toward a certain direction by reversing the opposite direction of road segments. Figure 1 shows a change of road direction under contraflow operation. Contraflow has been primarily used as a part of evacuation schemes.