A highway strip, road runway or road base is a section of a highway, motorway or other form of public road that is specially built to act as a runway for (mostly) military aircraft and to serve as an auxiliary military air base. These runways allow military aircraft to continue operating even if their regular air bases, some of the most vulnerable targets in any war, are degraded or 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. During the Cold War highway strips were systematically built on both sides of the Iron Curtain, in many cases in response to the Six Day War and Operation Focus in 1967, where the Israeli Air Force in a surprise air strike disabled many of their opponents' air bases in just a few hours. Countries that have built highway strips include both West and East Germany, Singapore, North Korea, Taiwan, Sweden, Finland, Bulgaria, Switzerland, Poland, India, Pakistan and Czechoslovakia.
Design
The strips are usually 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 any debris before use by aircraft. Road runways can however also be quite small—the short runways built in the Swedish Bas 90 system are commonly only in length. The STOL-capability of the Viggen and Gripen allowed for such short runways. 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.
Around the world
A number of countries around the world utilise the strategy of highways constructed to double as auxiliary airbases in the event of war.
Australia
While not designed for military use, in outback Australia some sections of highway are maintained as emergency runways for use by the Royal Flying Doctor Service.
Bosnia and Herzegovina
In Glamoč, Bosnia and Herzegovina, the M15 road was used as a military airstrip. There is a clear example of how the road was widened for the needs of airplane landing.
China
In 1989 China conducted its first highway strip drills. They have since been conducted at later dates and in different areas of the country. In 2014 Chinese forces landed warplanes on a highway strip in Henan province for the first time.
Cyprus
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 A1 Limassol–Nicosia Highway () and one near the western end of the A5 Limassol–Larnaca highway (). The third is a much smaller strip located on the A6 Limassol-Paphos Highway near to Paphos International Airport.
Estonia
During the Operation Saber Strike exercises in 2016 and 2018, A-10 Thunderbolt II aircraft from the US Air National Guard operated from former Warsaw Pact road runways in Estonia.
Finland
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 (), 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.