A traffic lane is the part of a road that's used for vehicles travelling in one direction. It's a common feature of multilane roadways and busier two-lane roads to help control the flow of traffic, prevent vehicles from colliding with each other and reduce traffic congestion. Traffic lanes are usually painted or have clear markings to indicate what movements are permitted in each lane. Many driving tests are failed each year because of inappropriate or potentially dangerous use of road and traffic lanes especially on approaches to junctions and roundabouts.
Generally, road lanes are painted white with dotted or solid lines separating them to indicate what movements are allowed. There may also be road signs and/or arrows showing which lanes are for turning or merging.
Some roadways and bridges are only 4.6 metres (15 ft) wide and are designed for one lane of traffic in each direction. They are commonly known as country roads or alleys and require that drivers travelling in opposite directions slow down to a safe distance before passing each other.
On busy roads, there are sometimes lanes that allow drivers to accelerate or merge onto the road more quickly. These are typically marked '2+ lane', 'carpool lane' or 'high occupancy vehicle' (HOV) lanes and require a vehicle to have at least two occupants. There are also reversible lanes on some roads to match peak-flow traffic conditions. When a reversible lane is in use, there may be flashing yellow arrows to warn drivers that they are not permitted to turn in this lane.