A highway strip or road runway is a section of a highway or motorway that is specially built to allow landing of (mostly) military aircraft and to serve as a military airbase. These were built to allow military aircraft to operate even if their airbases, the most vulnerable targets in any war, are destroyed.
The first highway strips were constructed near the end of World War II in Nazi Germany, where the well developed Reichsautobahn system allowed aircraft to use the motorways. In the Cold War highway strips were systematically built on both sides of the Iron Curtain, mostly in the two Germanys, but also in North Korea, Taiwan, Sweden, Finland, Switzerland, Poland, Pakistan and Czechoslovakia.
The strips are usually 2 to 3.5 kilometres (1.2 to 2.2 mi) long straight sections of the highway, where any central reservation is made of crash barriers that can be removed quickly (in order to allow airplanes to use the whole width of the road), and other features of an airbase (taxiways, airport ramps) can be built. The road will need a thicker than normal surface and a solid concrete base. The specialized equipment of a typical airfield are stored somewhere nearby and only carried there when airfield operations start. The highway strips can be converted from motorways to airbases typically within 24 to 48 hours. The road would need to be swept to remove all debris before any aircraft movement could take place. In the case of Finnish road airbases, the space needed for landing aircraft is reduced by means of a wire, similar to the CATOBAR system used on some aircraft carriers.
A number of countries around the world utilise the strategy of highways constructed to double as auxiliary airbases in the event of war.
While not designed for military use, in rural Australia several sections of highway are maintained as potential runways for use by the Royal Flying Doctor Service of Australia.
In the Winter War of 1939-1940 the Finnish Air Force re-deployed its aircraft to makeshift airfields including frozen lakes to preserve them against Soviet air attack. The tactic was successful, with Soviet air raids on bases causing little damage and the vastly outnumbered Finnish aircraft scoring a high number of aerial victories.
Throughout the Cold War the Finnish Air Force maintained a network of secondary airfields including civilian airports and road bases to improve survivability and effectiveness in the event of war.
As of 2017, all aircraft in the Finnish Air Force are capable of operating from road bases.
Currently Finland conducts drills on its road bases (maantietukikohta), around once a year. In the Baana 16 exercise in 2016 the Finnish Air Force flew F/A-18C and BAE Hawk, Pilatus PC-12 and C295M aircraft from a highway in Lusi. The Finnish Air Force uses arresting cables to quickly stop F/A-18s, which were originally designed to operate from aircraft carriers. The Swedish Air Force also took part in the 2015 and 2016 exercises, flying Gripen fighters.
Germany has a number of highway strips (NLP-Str - Notlandeplätze auf Straßen, emergency airfields on roads).
After the Turkish invasion of Cyprus, three highway strips were built in the Greek part of Cyprus, easily recognisable by a runway centre line and markings for the touchdown zone. They also all have aircraft turning areas at either end. One is located on the Limassol–Nicosia Highway (5,200 m or 17,100 ft) and one of the Limassol–Larnaca highway (5,000 m or 16,000 ft). The third is a much smaller strip located on the Limassol-Paphos Highway near to Paphos International Airport.
India has successfully tested its runway strip on a stretch of the Yamuna Expressway in Uttar Pradesh on 21 May 2015. It was built at a cost of ₹13,000 Cr for its combat jets of the IAF, a first for military aviation in the country. In June 2016, the Minister for Road Transport and Highways, Nitin Gadkari announced that the government was considering developing 'Road Runways' for commercial operations as well.
In Pakistan, The M-1 Motorway (Peshawar-Islamabad) and the M-2 Motorway (Islamabad-Lahore) each include two emergency runway sections of 2,700 m (9,000 ft) length each. The four emergency runway sections become operational by removing removable concrete medians using forklifts. The Pakistan Air Force (PAF) has used the M2 motorway as a runway on two occasions: for the first time in 2000 when it landed an F-7P fighter, a Super Mushak trainer and a C-130 and, again, in 2010. On the last occasion, the PAF used a runway section on the M2 motorway on 2 April 2010 to land, refuel and take-off two jet fighters, a Mirage III and an F-7P, during its Highmark 2010 exercise.
A large number of highway strips (DOL - Drogowy Odcinek Lotniskowy, lit "road airfield section") were built in Poland. As of 2003, only one highway strip is used annually for an exercise.
The Republic of Singapore Air Force periodically conducts an "alternate runway exercise". It was first conducted on April 17 1986 with F-5 and A-4 aircraft.
After an eight year gap, the seventh exercise, "Torrent 2016", was conducted near Tengah Air Base in November 2016. Signs, street lights and other fixtures were removed, and landing equipment installed temporarily, which included mobile arresting gear for the first time. F-15SG and F-16C/D fighters participated in the 2016 exercise.
Sweden started to build a few 1,500 m road strips (vägbas, literally meaning "road base"), from around 1949. The Six-Day War in 1967 (where the Egyptian Air Force was grounded by a quick surprise attack on air bases) inspired further development. The Viggen fighter/bomber was designed for shorter and narrower road strips which were built in fairly high numbers.
The Swedish Air Force has not practiced using their road bases for around a decade, but in 2015 and 2016 its Saab JAS 39 Gripen fighters participated in Finnish Air Force road base drills.
Taiwan built a number of highway strips (戰備跑道 , lit. "war spare runway").
A large number of highway strips were built in the former USSR.(Аэродромный Участок Дороги, "airfield part of road").