Arterial road
Encyclopedia
Road
A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...
. The primary function of an arterial road is to deliver traffic from collector roads to freeways, and between urban centres at the highest level of service
Level of service
Level of service is a measure used by traffic engineers to determine the effectiveness of elements of transportation infrastructure. LOS is most commonly used to analyze highways by categorizing traffic flow with corresponding safe driving conditions...
possible. As such, many arteries are limited-access roads, or feature restrictions on private access. Though the design of arterial roads varies from country to country, city to city, and even within those cities, they share a number of common design characteristics. In many cities, arteries are arranged in concentric circles (commonly referred to as a ring road
Ring road
A ring road, orbital motorway, beltway, circumferential highway, or loop highway is a road that encircles a town or city...
) or in a grid. Many jurisdictions also classify arterial roads as either principal (major) or minor.
In traffic engineering hierarchy, an arterial road delivers traffic between collector roads and freeways. For new arterial roads, intersections are often reduced to increase 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...
. In California, arterial roads are usually spaced every half mile, and have intersecting collector(s) and streets. Some arterial roads, if having a small fraction of intersections and driveways compared to most arterial roads, are also considered to be expressways in some countries and some states of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Definition
The Traffic Engineering Handbook describes Arterials as being either principal or minor. Both classes serve to carry longer-distance flows between important centers of activity. Arterials are laid out as the backbone of a traffic network and should be designed to afford the highest level of serviceLevel of service
Level of service is a measure used by traffic engineers to determine the effectiveness of elements of transportation infrastructure. LOS is most commonly used to analyze highways by categorizing traffic flow with corresponding safe driving conditions...
, as is practical.
Development
The construction and development of arterial roads is achieved through two methods. By far the most common is the upgrading of an existing right-of-way during subdivision development. When existing structures prohibit the widening of an existing road however, bypassesBypass (road)
A bypass is a road or highway that avoids or "bypasses" a built-up area, town, or village, to let through traffic flow without interference from local traffic, to reduce congestion in the built-up area, and to improve road safety....
are often constructed. Because of the placement and general continuity of arterial road corridors
Easement
An easement is a certain right to use the real property of another without possessing it.Easements are helpful for providing pathways across two or more pieces of property or allowing an individual to fish in a privately owned pond...
, sewers, water mains, conduits and other infrastructure are placed beneath or beside the roadbed.
Specifications
As arterial roads are designed for unimpeded high-speed movement, traffic signals are used at most intersections (except where the intersecting road is a minor side street, in which case a stop signStop sign
A Stop sign is a traffic sign to notify drivers that they must stop before proceeding.-Specifications:The Vienna Convention on Road Signs and Signals proposed standard stop sign diameters of 0.6, 0.9 or 1.2 metres. UK and New Zealand stop signs are 750, 900 or 1200 mm, according to sign...
is used instead). 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.
The width of arterial roads can range from four lanes to ten or more. Some are divided
Divided Highway
Divided Highway is a compilation album by American rock band The Doobie Brothers, released in 2003. . All tracks are taken from the albums Cycles and Brotherhood .-Track listing:...
at the center, while others share a common center lane, such as a contraflow lane or central turning lane.
Environmental issues
As with other roadway types, environmental consequences derive from arterial roadways, including air pollution generation, noise pollution and surface runoffSurface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
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. 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.