Editing Ring road (section)

==Background==
[[File:Sydney-orbital-black-line.png|thumb|alt=Map of the Sydney orbital network|The [[Sydney Orbital Network]], New South Wales, Australia]]
[[File:Tribiano - tangenziale est esterna.jpg|thumb|The [[Autostrada A58]], the [[Milan]] external east ring road, Italy. Together with the [[Autostrada A50]] (Milan west ring road), the [[Autostrada A51]] (Milan east ring road) and the [[Autostrada A52]] (Milan north ring road), it is the largest system of ring roads around a city in Italy, for a total length greater than {{convert|100|km}}.<ref name="auto">{{cite web|url=https://www.milanocittastato.it/evergreen/forse-non-sapevi-che/7-curiosita-sulla-tangenziali-di-milano/|title=7 cose che forse non sapevi delle TANGENZIALI di Milano|access-date=13 June 2024|language=it}}</ref>]]
[[Bypass (road)|Bypasses]] around many large and small towns were built in many areas when many old roads were converted to four-lane status in the 1930s to 1950s, such as those along the [[National Road|Old National Road]] (now generally [[U.S. Route 40|U.S. 40]] or [[Interstate 70]]) in the United States, leaving the old road in place to serve the town or city, but allowing through travelers to continue on a wider, faster and safer route.

Construction of fully circumferential ring roads has generally occurred more recently, beginning in the 1960s in many areas, when the U.S. [[Interstate Highway System]] and similar-quality roads elsewhere were designed. Ring roads have now been built around numerous cities and metropolitan areas, including cities with multiple ring roads, irregularly shaped ring roads and ring roads made up of various other long-distance roads.

[[London]] has three ring roads (the [[M25 motorway]], the [[A406 road|North]] and [[A205|South Circular]] roads and the [[London Inner Ring Road|Inner Ring Road]]). [[Birmingham]] also has three ring roads which consist of the [[Birmingham Box]]; the [[A4540]], commonly known as the Middleway; and the [[A4040]], the Outer Ring Road. Birmingham once had a fourth ring road, the [[A4400]]. This has been partially demolished and downgraded to improve traffic flow into the city. Other British cities have two: [[Leeds]], [[Sheffield]], [[Norwich]] and [[Glasgow]]. [[Cleveland, OH]] and [[San Antonio, TX]], in the [[United States]], also each have two, while [[Houston, Texas]] will have three official ring roads (not including the downtown freeway loop). Some cities have far more{{snd}} [[Beijing]], for example, has [[Ring roads of Beijing|six ring roads]], simply numbered in increasing order from the city center (though skipping #1), while Moscow has five, three innermost ([[Central Squares of Moscow]], [[Boulevard Ring]] and [[Garden Ring]]) corresponding to the concentric lines of fortifications around the ancient city, and the two outermost ([[MKAD]] and [[Third Ring Road (Moscow)|Third Ring]]) built in the twentieth century, though, confusingly, the Third Ring was built last.

Geographical constraints can complicate the construction of a complete ring road. For example, the [[Interstate 695 (Maryland)|Baltimore Beltway]] in [[Maryland]] formerly crossed [[Baltimore Harbor]] on a high arch [[Francis Scott Key Bridge (Baltimore)|bridge]] prior to its collapse in 2024, and much of the partially completed [[Stockholm Ring Road]] in [[Sweden]] runs through tunnels or over long bridges. Some towns or cities on sea coasts or near rugged mountains cannot have a full ring road. Examples of such partial ring roads are Dublin's [[M50 motorway (Ireland)|ring road]]; and, in the US, [[Interstate 287]], mostly in [[New Jersey]] (bypassing New York City), and [[Interstate 495 (Massachusetts)|Interstate 495]] around [[Boston]], none of which completely circles these seaport cities.

In other cases, adjacent international boundaries may prevent ring road completion. Construction of a true ring road around [[Detroit]] is effectively blocked by its location on the border with Canada and the [[Detroit River]]; although constructing a route mostly or entirely outside city limits is technically feasible, a true ring around Detroit would necessarily pass through Canada, and so [[Interstate 275 (Michigan)|Interstate 275]] and [[Interstate 696]] together bypass but do not encircle the city. Sometimes, the presence of significant natural or historical areas limits route options, as for the long-proposed [[Washington Outer Beltway|Outer Beltway]] around Washington, D.C., where options for a new western [[Potomac River]] crossing are limited by a nearly continuous corridor of heavily visited scenic, natural, and historical landscapes in the [[Mather Gorge|Potomac River Gorge]] and adjacent areas.

When referring to a road encircling a capital city, the term "beltway" can also have a political connotation, as in the [[United States|American]] term "[[Inside the Beltway (terminology)|Inside the Beltway]]", derived [[metonymy|metonymically]] from the [[Interstate 495 (Capital Beltway)|Capital Beltway]] encircling Washington, D.C.