A circuit , also called a circuit , is a closed race track . In motorsport, circuit races are held on circuits in which the course is repeatedly lapped by two or more automobiles driving on the same route at the same time. In contrast to a circuit, the start and finish of an open racetrack are separate and the route is only driven once.
The length of a race lap can vary widely. Kart tracks are only about one kilometer long, while circuits for touring cars and formula racing are usually between 3.5 and 7 km long. Longer courses like the Nordschleife of the Nürburgring are 20 to 25 kilometers long , depending on the route variant. The longest route on which competitions with an international title were held in the post-war period was the Targa Florio in Sicily with a lap length of over 70 km. The longest route used for sports car races was the Mille Miglia , a triangular course in Italy over around 1,600 kilometers of otherwise public roads that was only driven once per race.
A distinction is made with regard to circular routes
- the direction of travel clockwise or counterclockwise (or in the form of an eight);
- the routing: street courses have right and left curves, whereas oval courses only consist of a maximum of four left or four right curves;
- the floor covering made of asphalt , concrete , grass , earth , sand , gravel or ice ;
- Usage: Formula racing , touring car racing , sports car racing , motorcycle racing , kart racing , motocross , rallycross , autocross , speedway , ice speedway etc .;
- the duration of use: temporary racetracks such as street courses or airfield courses are only set up temporarily, while permanent racetracks can be used at any time.
In running, hourly runs are held on circular courses in the ultramarathon . The lap length varies between one and several kilometers, on which either 6-hour , 12-hour or 24-hour runs are completed. There are also competitions of more than 24 hours on longer routes. On the 400-meter track, the direction of running is changed sometimes every hour in competitions lasting 12 hours and up to prevent the athletes from one-sided fatigue. This shape is also not uncommon on fin tracks .
Circular courses are of particular importance for the DLV - and therefore IAAF - approval as a best-list route. The start and finish of an event away from the stadium may not be more than 50% of the route length apart. Together with other criteria, this regulation ensures international comparability of competition courses.