Carpool lanes

A high-occupancy vehicle lane (also known as an HOV lane, carpool lane, diamond lane, 2+ lane, and transit lane or T2 or T3 lanes in Australia and New Zealand) is a restricted traffic lane reserved at peak travel times or longer for the exclusive use of vehicles with a driver and one or more passengers, including carpools, vanpools, and transit buses. The normal minimum occupancy level is 2 or 3 occupants. Many jurisdictions exempt other vehicles, including motorcycles, charter buses, emergency and law enforcement vehicles, low-emission and other green vehicles, and/or single-occupancy vehicles paying a toll. HOV lanes are normally created to increase average vehicle occupancy and persons traveling with the goal of reducing traffic congestion and air pollution, although their effectiveness is questionable.

Regional and corporate-sponsored vanpools, carpools, and rideshare communities give commuters a way to increase occupancy. For places without such services, online rideshare communities can serve a similar purpose.Slugging lines are common in some places, where solo drivers pick up a passenger to share the ride and allow use of the HOV lane. High-occupancy toll lanes (HOT lanes) have been introduced in the United States to allow solo driver vehicles to use the lane on payment of a variable fee, which usually varies with demand.

The introduction of HOV lanes in the United States progressed slowly during the 1970s and early 1980s. Major growth occurred from the mid-1980s to the late 1990s. The first freeway HOV lane in the United States was implemented in the Henry G. Shirley Memorial Highway in Northern Virginia, between Washington, DC, and the Capital Beltway, and was opened in 1969 as a bus-only lane. The busway was opened in December 1973 to carpools with four or more occupants, becoming the first instance in which buses and carpools officially shared a HOV lane over a considerable distance.

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Wikipedia