Anarterial road orarterial thoroughfare is a high-capacityurban road that sits belowhighways on theroad hierarchy in terms oftraffic flow andspeed.[1][obsolete source][2] The primary function of an arterial road is to deliver traffic fromcollector roads tohighways orexpressways, and between urban hubs at a relatively highlevel of service. Therefore, many arteries arelimited-access roads or feature restrictions on private access. Because of their relatively highaccessibility, many major roads face large amounts of land use and urban development, making them significant urban places.[3]
In traffic engineering hierarchy, an arterial road delivers traffic betweencollector roads andhighways. For new arterial roads, intersections are often reduced to increasetraffic flow. In California, arterial roads are usually spaced every half mile, and have intersecting collector(s) and streets.
The Traffic Engineering Handbookdescribes "Arterials" as being either principal or minor. Both classes serve to carry longer-distance flows between important centers of activity. The handbook also states that arterials are laid out as the backbone of a traffic network andshould be designed to afford the highestlevel of service, as is practical.[4]
The construction and development of arterial roads is achieved through two methods. By far the most common is the upgrading of an existingright-of-way during subdivision development. When existing structures prohibit the widening of an existing road however,bypasses are often constructed. Because of the placement and general continuity of arterial roadcorridors, sewers, water mains, conduits and other infrastructure are placed beneath or beside the roadbed.
In North America,signalizedat-grade intersections are used to connect arterials to collector roads and other local roads (except where the intersecting road is a minor side street, in which case astop sign is used instead). In Europe, large roundabouts are more commonly seen at the busier junctions. Speed limits are typically between 30 and 50 mph (50 and 80 km/h), depending on the density of use of the surrounding development. In school zones, speeds may be further reduced; likewise, in sparsely developed or rural areas, speeds may be increased. In western Canada, where highways are scarce compared to the rest of North America, flashing early-warning amber lights are sometimes placed ahead of traffic lights on heavy signalized arterial roads so the speed limits can be raised to speeds of over 80 km/h. These warning lights are commonly found on high-speed arterial roads in British Columbia.[citation needed]
The width of arterial roads ranges from four lanes to ten or more.
As with other roadway environmental consequences derive from arterial roadways, includingair pollution generation,noise pollution andsurface runoff of water pollutants. Air pollution generation from arterials can be rather concentrated, since traffic volumes can be relatively high, and traffic operating speeds are often low to moderate.[5] Sound levels can also be considerable due to moderately high traffic volumes characteristic of arterials, and also due to considerable braking and acceleration that often occur on arterials that are heavily signalized.[6]
The dictionary definition ofarterial road at Wiktionary