A diamond lane is a special lane

Lane

A lane is a part of the roadway within a road marked out for use by a single line of vehicles in such a way as to control and guide drivers for the purpose of reducing traffic conflicts. Most public roads have at least two lanes, one for traffic in each direction, separated by Lane markings...

 on a street

Street

A street is a paved public thoroughfare in a built environment. It is a public parcel of land adjoining buildings in an urban context, on which people may freely assemble, interact, and move about. A street can be as simple as a level patch of dirt, but is more often paved with a hard, durable...

 or highway

Highway

A highway is any public road. In American English, the term is common and almost always designates major roads. In British English, the term designates any road open to the public. Any interconnected set of highways can be variously referred to as a "highway system", a "highway network", or a...

 that is reserved for specific types of traffic

Traffic

Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...

. These lanes are usually marked with white diamonds

Rhombus

In Euclidean geometry, a rhombus or rhomb is a convex quadrilateral whose four sides all have the same length. The rhombus is often called a diamond, after the diamonds suit in playing cards, or a lozenge, though the latter sometimes refers specifically to a rhombus with a 45° angle.Every...

, hence their name. Diamond lanes are generally the right-most or left-most lane on the road. They are usually implemented to provide ways through traffic congestion

Traffic congestion

Traffic congestion is a condition on road networks that occurs as use increases, and is characterized by slower speeds, longer trip times, and increased vehicular queueing. The most common example is the physical use of roads by vehicles. When traffic demand is great enough that the interaction...

, for safety reasons, and to encourage environmentally friendly transportation. A diamond lane may be intended for a specific type of traffic, or for several types. The intended use of a diamond lane is marked by traffic signs. In most areas, violating the rules of a diamond lane is punishable by a fine.

Some common examples are:

• High-occupancy vehicle lane
  High-occupancy vehicle lane
  In transportation engineering and transportation planning, a high-occupancy vehicle lane is a lane reserved for vehicles with a driver and one or more passengers...
  
  , also known as a carpool lane. These are typically freeway lanes intended for multiple occupant or "green vehicle
  Green vehicle
  A green vehicle or environmentally friendly vehicle is a road motor vehicle that produces less harmful impacts to the environment than comparable conventional internal combustion engine vehicles running on gasoline or diesel, or one that uses alternative fuels...
  
  s" (such as hybrid
  Hybrid vehicle
  A hybrid vehicle is a vehicle that uses two or more distinct power sources to move the vehicle. The term most commonly refers to hybrid electric vehicles , which combine an internal combustion engine and one or more electric motors.-Power:...
  
   or electric
  Electric vehicle
  An electric vehicle , also referred to as an electric drive vehicle, uses one or more electric motors or traction motors for propulsion...
  
   cars).
• Bike lane, sometimes referred to as segregated cycle facilities
  Segregated cycle facilities
  Segregated cycle facilities are marked lanes, tracks, shoulders and paths designated for use by cyclists from which motorised traffic is generally excluded...
  
  . Separating bicycle traffic from pedestrian
  Pedestrian
  A pedestrian is a person traveling on foot, whether walking or running. In some communities, those traveling using roller skates or skateboards are also considered to be pedestrians. In modern times, the term mostly refers to someone walking on a road or footpath, but this was not the case...
  
   or motor vehicle
  Motor vehicle
  A motor vehicle or road vehicle is a self-propelled wheeled vehicle that does not operate on rails, such as trains or trolleys. The vehicle propulsion is provided by an engine or motor, usually by an internal combustion engine, or an electric motor, or some combination of the two, such as hybrid...
  
   traffic is typically safer and improves traffic flow
  Traffic flow
  Traffic flow, in mathematics and civil engineering, is the study of interactions between vehicles, drivers, and infrastructure , with the aim of understanding and developing an optimal road network with efficient movement of traffic and minimal traffic congestion problems.-History:Attempts to...
  
  .
• Bus lane
  Bus lane
  A bus lane or bus only lane is a lane restricted to buses, and generally used to speed up public transport that would be otherwise held up by traffic congestion...
  
  , an uncongested lane for buses to travel, load, or unload in.
• Emergency vehicle
  Emergency vehicle
  An emergency vehicle is any vehicle that is designated and authorized to respond to an emergency. These vehicles are usually operated by designated agencies, often part of the government, but also run by charities, non-governmental organizations and some commercial companies...
  
   lane, to help emergency vehicles get to their destination as fast as possible while avoiding traffic congestion.
• Taxicab
  Taxicab
  A taxicab, also taxi or cab, is a type of vehicle for hire with a driver, used by a single passenger or small group of passengers, often for a non-shared ride. A taxicab conveys passengers between locations of their choice...
  
   lanes, most often found at airports or other transit hubs for passenger loading and unloading.