The TT Circuit Assen is a motorsport race track built in 1955 and located in Assen, Netherlands. Host of the Dutch TT, it is popularly referred to as "The Cathedral" of motorcycling by the fans of the sport. The venue has the distinction of holding the most Grand Prix motorcycle races every year (except 2020) since the series was created in 1949. It has a capacity of 110,000 spectators, including 60,000 seats. Since 1992, the circuit has also been part of the World SBK calendar except the 2020 season.
The original Assen track was first used for the 1926 Dutch TT (Tourist Trophy) race, after the first 1925 event was held on country roads through the villages of Rolde, Borger, Schoonloo and Grolloo, and organized by the Motorclub Assen en Omstreken. The brick- and semi-paved track had a length of 28.57 km (17.75 mi). The winner was Piet van Wijngaarden on a 500 cc Norton with an average speed of 91.4 km/h (56.8 mph). From 1926 on the Dutch TT was held at Assen on a street circuit through De Haar, Barteldsbocht, Oude Tol, Hooghalen, Laaghalen and Laaghalerveen.
In 1951 the Italian Umberto Masetti took the record on a 500 cc Gilera with an average speed of 162.35 km/h (100.88 mph). In 1954, Geoff Duke of Great Britain reached 170.69 km/h (106.06 mph). The circuit remained unchanged until 1955, when a whole new circuit was built by using a third of the original street circuit, joined with purpose-built sections, but less than a third of the length and much more like a modern road racing circuit.
In the period of 1999-2002, the circuit invested millions in upgrades. In 1999, the circuit management placed a new main grandstand and hospitality buildings. In 2000, a new Race Control tower was built, as well as 34 newly equipped pit boxes, a new media and medical centre. Between September 2001 and April 2002, another 9 million Euro's is spent on the enlargement of the paddock area from 40 to 60.000 square metres. This upgrade meant that the Veenslang and Ruskenhoek corners had to be altered. The main straight has also moved about 50 metres eastwards and a new two-lane tunnel now connects the paddock with the main entrance road and the media accreditation / welcome centre. The Mandeveen and Duikersloot corners have been moved back by 10 metres to accommodate larger run-offs and gravel beds at the southern part of the circuit. That part of the track has also been resurfaced with new asphalt. In total, the circuit has been shortened from 6.049 km (3.759 mi) to 6.027 km (3.745 mi). The total amount of costs on these upgrades is 23 million Euro's.
In 2005, the grandstand at the Geert Timmer corner was slightly altered. In order to improve the gravel run-off length, the grandstand was made in a 'floating' manner to accommodate the extra space that was needed. The lay-out of the circuit was also slightly altered.
The circuit was fundamentally redesigned again in 2006, becoming the so-called A-Style Assen TT Circuit. All alterations aside, only one section of the circuit is original; the finish line never moved. On 21 September 2009 it was announced that a new chicane will be added, after a request from the A1GP organization, however A1GP was unable to start the 2009–2010 season and as a substitute the Superleague Formula replaced A1GP.
Assen race track was built in 1955, and initially had a length of 7.705 km (4.788 mi). The current track has a length of 4.555 km (2.830 mi) with the mixture of super fast flat-out and slow corners. The longest straight is 560 m (1,840 ft). The curves in Assen were traditionally banked and the surface is extremely grippy, so the riders were able to drive much faster on the course than other circuits. Today these sloped or curved bends have been modified due to safety issues.
On 6 July 2004, the organisation announced plans for an amusement park located to the north of the track. In 2006 the northern loop was removed and the length was shortened to 4.555 km (2.830 mi). The new centre is expected to be visited by 300,000 people, and the total investment is approximately €85 million.
The official fastest race lap records at the TT Circuit Assen are listed as:
- April: Superbike World Championship, Sidecar World Championship
- June: MotoGP Dutch TT, MotoE World Cup, RSG Hansa Pokal Rennen
- July: Truckstar Festival
- August: Supercar Challenge, GT & Prototype Challenge, ADAC Racing Weekend
- September: Assen Classic GP
- October: Supercar Challenge, GT & Prototype Challenge
- November: JYR XIV American style
- ADAC GT Masters (2008–2011)
- ATS Formel 3 Cup (2004–2012)
- British Superbike Championship (2012–2019)
- Champ Car World Series (2007)
- Deutsche Tourenwagen Masters (2019–2021)
- European Truck Racing Championship (2004–2005, 2009)
- FIM Endurance World Championship (1979–1980, 1995–1996, 2003–2006)
- Formula Renault Northern European Cup (2006–2017)
- Superleague Formula (2010–2011)
- TCR Europe Touring Car Series (2018)
- W Series (2019)
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- Sports, Dorna. "Safety upgrades | MotoGP™". www.motogp.com.
- (in Dutch) Dagblad van het Noorden Archived 17 July 2011 at the Wayback Machine
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- "1992-09-11 to 1992-09-13 World Superbike Dutch Round Race 2". Retrieved 13 June 2022.