Controlled-access highway

A controlled-access highway is a type of <a href="/facts/Highway/2nxmEmgX">highway</a> that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms include throughway or thruway and <a href="/facts/Parkway/uejggH7Q">parkway</a>. Some of these may be <a href="/facts/Limited-access_highways/4GMP4AB6">limited-access highways</a>, although this term can also refer to a class of highways with somewhat less isolation from other traffic.
In countries following the <a href="/facts/Vienna_Convention_on_Road_Signs_and_Signals/VLh7vjAl">Vienna convention</a>, the motorway qualification implies that walking and parking are forbidden.
A fully controlled-access highway provides an unhindered flow of traffic, with no <a href="/facts/Traffic_signals/v5pwcfsQ">traffic signals</a>, <a href="/facts/Intersection_(road)/b51M4MQx">intersections</a> or <a href="/facts/Frontage/Tag4bkab">property access</a>. They are free of any <a href="/facts/At-grade_intersection/b51M4MQx">at-grade crossings</a> with other roads, railways, or pedestrian paths, which are instead carried by <a href="/facts/Overpass/bHSRAB3f">overpasses</a> and <a href="/facts/Underpass/PJNSaSIw">underpasses</a>. Entrances and exits to the highway are provided at <a href="/facts/Interchange_(road)/QMSHwNhF">interchanges</a> by slip roads (ramps), which allow for speed changes between the highway and <a href="/facts/Arterial_road/4a9AfQ7p">arterials</a> and <a href="/facts/Collector_road/6PsYh4FU">collector roads</a>. On the controlled-access highway, opposing directions of travel are generally separated by a <a href="/facts/Median_strip/nS6eyoYe">median strip</a> or central reservation containing a <a href="/facts/Traffic_barrier/eYynyFKs">traffic barrier</a> or grass. Elimination of conflicts with other directions of traffic dramatically improves safety, while increasing traffic capacity and speed.
Controlled-access highways evolved during the first half of the 20th century. <a href="/facts/Italy/tUf0PDYF">Italy</a> was the first country in the world to build controlled-access highways reserved for fast traffic and for motor vehicles only. Italy opened its first <a href="/facts/Autostrada/5dyyCBW7">autostrada</a> in 1924, <a href="/facts/Autostrada_A8_(Italy)/EPobtd9p">A8</a>, connecting <a href="/facts/Milan/0xrtbPdt">Milan</a> to <a href="/facts/Varese/3P3xUf9v">Varese</a>. Germany began to build its first controlled-access <a href="/facts/Autobahn/t6uGo9j6">autobahn</a> without speed limits (30 kilometres [19 mi] on what is now <a href="/facts/Bundesautobahn_555/7mGzwwdY">A555</a>, then referred to as a dual highway) in 1932 between <a href="/facts/Cologne/U2qmyGga">Cologne</a> and <a href="/facts/Bonn/eCSu8vB1">Bonn</a>. It then rapidly constructed the first nationwide system of such roads. The first <a href="/facts/North_America/djNjCQIl">North American</a> freeways (known as parkways) opened in the <a href="/facts/New_York_City/YlyvFmVC">New York City</a> area in the 1920s. Britain, heavily influenced by the railways, did not build its first motorway, the <a href="/facts/Preston_By-pass/Gb8d1ago">Preston By-pass</a> (<a href="/facts/M6_motorway/wTJPHe72">M6</a>), until 1958.
Most technologically advanced nations feature an extensive network of freeways or motorways to provide high-capacity urban travel, or high-speed rural travel, or both. Many have a national-level or even international-level (e.g. <a href="/facts/International_E-road_network/mWhrAPlu">European E route</a>) system of <a href="/facts/Route_number/YR0th6nn">route numbering</a>.

Controlled-access highway open-in-new

Controlled-access highway