View source for Arterial road

{{short description|High-capacity urban road}}
[[File:PageMillRoad.png|thumb|[[Page Mill Road]] in [[Palo Alto, California]], United States, is a typical arterial road in a suburban area; this also has an unprotected bike lane on the road shoulder]]

An '''arterial road''' or '''arterial thoroughfare''' is a high-capacity [[urban area|urban]] road that sits below [[Controlled-access highway|highway]]s on the [[Hierarchy of roads|road hierarchy]] in terms of [[traffic flow]] and [[Speed limit#Maximum speed limits|speed]].<ref>{{cite tech report |author=FHWA |author-link=Federal Highway Administration |date=November 2000 |title=Road Function Classifications |url=https://rosap.ntl.bts.gov/view/dot/72608 |type=Booklet |publisher=FHWA |url-status=live |archive-url=https://web.archive.org/web/20090514070821/https://safety.fhwa.dot.gov/speedmgt/data_facts/docs/rd_func_class_1_42.pdf |archive-date=14 May 2009 |access-date=13 April 2025}}</ref>{{Obsolete source |reason=FHWA's 2023 Highway Functional Classification book divides arterial roads into major (which include highways) and minor. So, arterials today are not below highways, but rather include them. |date=April 2025}}<ref>{{cite web |title=Road classification |url=https://road-safety.transport.ec.europa.eu/european-road-safety-observatory/statistics-and-analysis-archive/roads/road-classification_en |publisher=European Commission |url-status=live |archive-url=https://web.archive.org/web/20241219203231/https://road-safety.transport.ec.europa.eu/european-road-safety-observatory/statistics-and-analysis-archive/roads/road-classification_en |archive-date=19 December 2024 |access-date=13 April 2025}}</ref> The primary function of an arterial road is to deliver traffic from [[collector road]]s to [[Controlled-access highway|highways]] or [[Limited-access road|expressways]], and between urban hubs at a relatively high [[Level of service (transportation)|level of service]]. Therefore, many arteries are [[limited-access road]]s or feature restrictions on private access. Because of their relatively high [[Accessibility (transport)|accessibility]], many major roads face large amounts of land use and urban development, making them significant urban places.<ref>{{Cite journal|last1=McLeod|first1=Sam|last2=Curtis|first2=Carey|date=2019|title=Contested urban streets: Place, traffic and governance conflicts of potential activity corridors|journal=Cities|language=en|volume=88|pages=222–234|doi=10.1016/j.cities.2018.11.002|s2cid=159002874}}</ref>

In traffic engineering hierarchy, an arterial road delivers traffic between [[collector road]]s and [[Controlled-access highway|highways]]. For new arterial roads, intersections are often reduced to increase [[traffic flow]]. In California, arterial roads are usually spaced every half mile, and have intersecting collector(s) and streets. 

== 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. The handbook also states that arterials are laid out as the backbone of a traffic network and ''should'' be designed to afford the highest [[Level of service (transportation)|level of service]], as is practical.<ref>{{cite book |title = Traffic Engineering Handbook |last = Neuman |first = Timothy R. |editor = Institute of Traffic Engineers |publisher = Prentice Hall |isbn = 978-0-13-926791-8 |year = 1992 |section = Roadway Geometric Design |page = 155 }}</ref>

== 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 (transportation)|right-of-way]] during subdivision development. When existing structures prohibit the widening of an existing road however, [[bypass (road)|bypasses]] are often constructed. Because of the placement and general continuity of arterial road [[easement|corridors]], sewers, water mains, conduits and other infrastructure are placed beneath or beside the roadbed.

== Specifications ==

In North America, [[traffic signal|signalized]] [[Intersection (road)|at-grade intersection]]s 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 a [[stop sign]] is used instead). In Europe, large roundabouts are more commonly seen at the busier junctions. Speed limits are typically between {{convert|30|and|50|mph|km/h|abbr=on|round=5}}, 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|date=April 2025}}

The width of arterial roads ranges from four lanes to ten or more.

==Environmental issues==
{{main|Roadway air dispersion model|Roadway noise}}

As with other roadway environmental consequences derive from arterial roadways, including [[air pollution]] generation, [[noise pollution]] and [[surface 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.<ref>{{cite web |url = http://www.epa.gov/scram001/dispersion_prefrec.htm |archive-url = https://archive.today/20121205004521/http://www.epa.gov/scram001/dispersion_prefrec.htm |url-status = dead |archive-date = December 5, 2012 |title = Roadway air dispersion model |publisher = United States [[United States Environmental Protection Agency|Environmental Protection Agency]] }}</ref>  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.<ref>{{cite magazine |first = C. Michael |last = Hogan |title = Analysis of highway noise |magazine = Journal of Water, Air, & Soil Pollution |volume = 2 |issue = 3 (Biomedical and Life Sciences and Earth and Environmental Science Issue) |pages = 387–392 |date = September 1973 |issn = 0049-6979 |doi = 10.1007/BF00159677 }}</ref>

== See also ==
* [[Grid plan]]
* [[History of urban planning]]
* [[Stroad]]

==References==
{{reflist}}

==External links==
*{{Wiktionary-inline}}
{{Road types}}

[[Category:Types of roads]]
[[Category:Arterial roads| ]]