In the context of traffic control, a lane is part of a roadway (carriageway) that is designated to be used by a single line of vehicles, to control and guide drivers and reduce traffic conflicts.
Most public roads (highways) have at least two lanes, one for traffic in each direction, separated by lane markings. On multilane roadways and busier two-lane roads, lanes are designated with road surface markings.
Major highways often have two multi-lane roadways separated by a median.
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Some roads and bridges that carry very low volumes of traffic are less than 4.6 metres (15 ft) wide, and are only a single lane wide. Vehicles travelling in opposite directions must slow or stop to pass each other.
In rural areas, these are often called country lanes. In urban areas, alleys are often only one lane wide. Urban and suburban one lane roads are often designated for one-way traffic.
Painted lane markings vary widely from country to country. In the United States, Canada, Mexico, Honduras, Puerto Rico, Virgin Islands and Norway, yellow lines separate traffic going opposite directions and white separates lanes of traffic traveling the same direction, but such is not the case in many European countries.
Lane markings are mostly lines painted on the road by a road marking machine, which can adjust the marking widths according to the lane type.
Traffic reports in California often refer to accidents being “in the number X lane.” The California Department of Transportation (Caltrans) assigns the numbers from left to right.
The far left passing lane is the number 1 lane. The number of the slow lane (closest to freeway onramps/offramps) depends on the total number of lanes, and could be anywhere from 2 to 8.