Controlled-access highway
The Vienna Convention on Road Signs and Signals defines a motorway as a road specially designed for motor traffic that does not serve properties bordering it. This definition requires separate carriageways for opposing directions, separated by a dividing strip or other means. The convention mandates that such roads do not cross at level with any road, railway, tramway track, or footpath. Entry points display a green or blue symbol to indicate the start of motorway regulations. Exits are marked with a different symbol to signal the end of those specific rules. Organizations like the OECD and PIARC have adopted definitions almost identical to the Vienna standard. British Standards describe a motorway as a limited-access dual carriageway road not crossed on the same level by other traffic lanes. The Institute of Transportation Engineers defines a freeway as a divided major roadway with full control of access and no crossings at grade. These standards apply to both toll and toll-free roads in many jurisdictions. Some countries distinguish between principal arterials serving long-distance movements and expressways crossing urban areas. A European definition from 2003 states that motorways must be reserved for specific categories of road motor vehicles. They prohibit pedestrians, animals, pedal cycles, mopeds, and agricultural vehicles from using these roads. The minimum speed is never lower than thirty kilometers per hour except where local laws dictate otherwise.
Italy opened its first controlled-access highway in 1924 connecting Milan to Varese. This route was known as the Autostrada dei Laghi or Lakes Motorway. It contained only one lane in each direction and featured no interchanges. Germany began planning the AVUS circuit in Berlin in 1907 and started construction in 1913. This closed circuit allowed vehicles to reach top speeds twice before returning to the entrance. The AVUS remained open for testing and racing until it connected to the nationwide Reichsautobahn network in 1940. Construction on the Bonn-Cologne Autobahn began in 1929 and opened in 1932 under Konrad Adenauer. The Long Island Motor Parkway opened in 1908 as a private venture in New York. It included banked turns, guard rails, and reinforced concrete tarmac but allowed left turns between connectors. Modern controlled-access highways originated in the early 1920s due to rapid automobile use and improved paving techniques. Britain did not build its first motorway, the Preston By-pass, until 1958. Canada developed the Queen Elizabeth Way which opened in 1937 featuring a cloverleaf interchange. Highway 401 later became the busiest highway in the world based on traffic volume data from the late twentieth century.
Freeways utilize grade separation through overpasses or underpasses to eliminate at-grade intersections with other roads. Access is typically provided only at these grade-separated interchanges rather than direct property connections. Some countries allow lower-standard right-in/right-out access for direct connections to side roads. Sophisticated interchanges allow smooth transitions between intersecting freeways and busy arterial roads. Speed limits are generally higher on freeways and occasionally nonexistent as seen on much of Germany's Autobahn network. Guide signs are often mounted on overhead gantries so drivers can see where each lane goes. Exit numbers commonly derive from the exit's distance in miles or kilometers from the start of the freeway. Public rest areas or service areas exist on some freeways along with emergency phones on the shoulder. Median strips separate opposite directions of traffic and may include crash barriers like Jersey barriers. Cross sections incorporate a minimum of two through-traffic lanes for each direction separated by a central median. Obstacle-free zones vary from three meters to five meters depending on local design standards. High-mast lighting concentrates light on the road but tall structures can lead to community opposition known as NIMBY effects. Tunnels and overpasses are constructed more frequently on motorways compared to other road types requiring complex equipment.
Motorways accounted for more than one quarter of all kilometers driven yet contributed only 8% of total European road deaths in 2006. Germany's Federal Highway Research Institute provided statistics showing fatality rates per billion vehicle kilometers were significantly lower on motorways than on all roads combined. In Austria, the fatality rate was 7.32 on all roads versus 2.15 on motorways. France recorded 7.12 fatalities per billion vehicle kilometers on all roads compared to 1.79 on motorways. Speed is considered one of the main contributory factors to collisions across Europe. Some countries achieved death reduction through better monitoring of speed using safety cameras or penalty points. One third of accidents in French motorways are due to sleepy driving according to Vinci Autoroutes data. Twenty-three percent of people killed on French motorways were not wearing seat belts while 98% of front-seat passengers wore them. Motorway fatalities decreased by 41% during the 2006, 2015 decade but increased by 10% between 2014 and 2015. Fatalities per thousand kilometers halved between 2006 and 2015 when accounting for network length. German motorways without a speed limit are 25% more deadly than those with a speed recommendation.
England and Wales use a numbering system separate from A-roads based on zones defined clockwise from the M1. The Preston Bypass was numbered M6 instead of A6(M) under the original scheme decided upon by authorities. Scotland reserves numbers 7, 8, and 9 for its motorways following the A-road rule strictly. Northern Ireland uses a distinct numbering system where major motorways are numbered M1 and M2. Ireland numbers motorways in series radiating anti-clockwise from Dublin starting with N1/M1 using numbers from 1 to 33. Australia uses alphanumeric route markers with M prefix for motorways replacing older Metroad or State Route markers. Hungary derives motorway numbers from original national highway numbers with an M prefix attached like M7. Germany assigns odd-numbered federal motorways generally north-south directions while even-numbered ones follow east-west paths. Italy marks all motorways with letter A followed by a number regardless of management concessionaire companies. Belgium prefixes some dual carriageways with A but references E-numbers when applicable for international routes. Croatia maintains independent motorway numbering prefixed by A separate from state route numbering systems.
Algeria's motorway network has about 1,500 kilometers in 2x3 lanes expanding increasingly along northern regions. Egypt connects Cairo with Alexandria via the Cairo-Alexandria Desert Road running 206 kilometers as the main motorway. Ethiopia opened the Addis Ababa-Adama Expressway in 2014 becoming the first expressway in that nation. Kenya hosts two Trans-African Highway network routes crossing its borders including the Lagos-Mombasa Highway. Morocco plans to expand its road network to include 2,800 kilometers of motorways and 1,200 kilometers of expressways by 2035. Mozambique classifies highways as national or primary roads given prefix N or EN followed by one or two-digit numbers. Nigeria possesses the largest highway network in West Africa with four Trans-African Highway routes situated within its borders. South Africa defines freeways where vehicles drawn by animals or pedal cycles are forbidden from using them. Argentina connects to the Pan-American Highway system with over 36,000 kilometers of paved roads total. Brazil completed Rodovia Anhanguera in 1953 as its first expressway upgrading an earlier undivided highway.
Common questions
What is the definition of a motorway according to the Vienna Convention on Road Signs and Signals?
The Vienna Convention defines a motorway as a road specially designed for motor traffic that does not serve properties bordering it. This standard requires separate carriageways for opposing directions separated by a dividing strip or other means. The convention mandates that such roads do not cross at level with any road, railway, tramway track, or footpath.
When did Italy open its first controlled-access highway known as the Autostrada dei Laghi?
Italy opened its first controlled-access highway in 1924 connecting Milan to Varese. This route was known as the Autostrada dei Laghi or Lakes Motorway. It contained only one lane in each direction and featured no interchanges.
How many fatalities occurred per billion vehicle kilometers on French motorways compared to all roads in 2006?
France recorded 7.12 fatalities per billion vehicle kilometers on all roads compared to 1.79 on motorways. Speed is considered one of the main contributory factors to collisions across Europe. Some countries achieved death reduction through better monitoring of speed using safety cameras or penalty points.
Which cities implemented freeway removal policies to reclaim land as boulevards or parks?
Cities like Seoul, Portland, New York City, Boston, San Francisco, Seattle, and Milwaukee implemented freeway removal policies. These cities demolished freeways and reclaimed land as boulevards or parks such as Cheonggyecheon in Seoul. Underground urban freeways using tunneling technologies have been employed in Madrid, Prague, Sydney, Brisbane, and Melbourne.
What numbering system does Germany use for federal motorways regarding direction?
Germany assigns odd-numbered federal motorways generally north-south directions while even-numbered ones follow east-west paths. Italy marks all motorways with letter A followed by a number regardless of management concessionaire companies. Belgium prefixes some dual carriageways with A but references E-numbers when applicable for international routes.