Oval track racing

Oval track racing is a form of closed-circuit automobile racing that is contested on an oval-shaped track. An oval track differs from a road course in that the layout resembles an oval with turns in only one direction, almost universally left (counter-clockwise orientation). Oval tracks are dedicated motorsport circuits, used predominantly in North America. They often have banked turns and some, despite the name, are not precisely oval, and can have unique variances in shape.

Oval track racing is the predominant form of auto racing in the United States. According to the 2013 National Speedway Directory, the total number of oval tracks, drag strips and road courses in the United States is 1,262, with 901 of those being oval tracks and 683 of those being dirt tracks. Major forms of oval track racing include stock car racing, open-wheel racing, sprint car racing, modified car racing, midget car racing and dirt track motorcycles.

Among the most famous oval tracks in North America are the Indianapolis Motor Speedway and Daytona International Speedway. Notable ovals in other countries include Rafaela in Argentina, Motegi in Japan, Lausitzring in Germany, Brooklands and Rockingham in the United Kingdom, Monza in Italy, and Montlhéry in France.



Track classification (size)
Oval tracks are classified based upon their size, surface, and shape. Their size can range from only a few hundred feet to over two and a half miles. Track surfaces can be dirt, congrete, asphalt, or a combination of concrete and asphalt. Some ovals in the early twentieth century had wood surfaces.

The definitions used to differentiate track sizes have changed over the years. It should be noted that while some tracks use terms such as "speedway" or "superspeedway" in their name, they may not meet the specific definitions used in this article.

The typical oval track consists of two parallel straights, connected by two 180° turns. Although most ovals generally have only two radii curves, they are usually advertised and labeled as four 90° turns.

Short tracks
A short track is an oval track less than 1.0 miles (1.6 km) long, with the majority being .5 mile or shorter. Drivers seeking careers in oval track racing generally serve their apprenticeship on short tracks before moving up to series which compete on larger tracks. Due to their short length and fast action, these tracks are often nicknamed "bullrings." Professional-level short tracks include Bristol, Martinsville, Richmond and Stafford.

Professional-level NASCAR races on short tracks usually utilize a 500-lap or 400-lap distance - with "laps" as the advertised measurement rather than miles. Short tracks in many cases, both professional-level and tracks at the local level, have lights installed and routinely host night races.

Mile ovals
Synonymous with the name, a 1 mi oval is a popular and common length for oval track racing. The exact measurements, however, can vary by as much as a tenth of a mile and still fall into that category. Most mile ovals are relatively flat-banked, with Dover being a notable exception. Other examples include Phoenix, Loudon, Milwaukee and Nazareth.

Intermediate tracks
Also referred to with the general term of "speedways," these courses are 1 to 2 mi in length, but the term is particularly reserved for 1.5 mi tracks. Since their size allows them to compromise high speeds with sightlines, they have become commonplace in major racing series that utilize oval tracks. During the race track construction boom of the 1990s, these tracks began to be labeled with the rather derogatory term "cookie cutter" tracks, as their differences were perceived to be minimal. Examples include Las Vegas, Atlanta, Kansas, Texas, Kentucky, Chicagoland and Charlotte.

In 1992, Charlotte became the first intermediate track to install lights and allow for night racing. It is now commonplace for these types of tracks to host night races.

Superspeedways
Superspeedways are at least 2.0 mi in length. There are seven superspeedways in the United States, the most famous being Indianapolis Motor Speedway and Daytona International Speedway, both 2.5 mi long. These tracks were built in 1909 and 1959 respectively. Indianapolis Motor Speedway was built as a facility for the automotive industry to conduct research and development. Daytona International Speedway was built as a replacement for the Daytona Beach Road Course, which combined the town's main street and its famous beach. Daytona hosts the Daytona 500, NASCAR's most prestigious race, while the Indianapolis Motor Speedway is home to the Indianapolis 500 and the Brickyard 400.

The longest superspeedway is the Talladega Superspeedway in Talladega, Alabama. Built in 1969, it is 2.66 mi long, and holds the current record for fastest speed in a stock car, lapping at an average of 216.309 mi/h and reaching 228 mph at the end of the backstretch. Daytona and Talladega are the pinnacle of stock car superspeedway racing, where restrictor plates are mandated by the sport's ruling body to reduce the high speeds created by their steep banking.

Other superspeedways used by NASCAR include the Michigan International Speedway (2.0 miles), Fontana (2.0 miles), and Pocono Raceway (2.5 miles). Fontana and Michigan are often considered intermediate tracks due to their similarities with 1.5-mile tracks, while Pocono and Indianapolis are sometimes classified separately, as they are the only long, flat tracks on the schedule. Fontana, which joins Indianapolis and Pocono as the only three superspeedways currently in use in the IZOD IndyCar Series, was the site of Gil de Ferran's qualifying lap of 241.428 mi/h in the CART FedEx Championship Series in 2000, presently the fastest lap recorded at an official race meeting.

The seventh superspeedway is Texas World Speedway, which is the original "sister track" to Michigan. The 2.0-mile oval, with its 22-degree banking, was the site of Mario Andretti's closed-course record of 214.158 mph which stood for 12 years. No major professional series have raced at TWS since the 1990s, however, the track's 1.8, 2.9 and 3.1-mile road courses are very popular with amateur racing clubs.

Track classification (shape)
While many oval tracks conform to the traditional symmetrical design, asymmetrical tracks are not uncommon. Pocono for example, has the shape of a scalene triangle with rounded corners. Darlington was built with an egg-shape to accommodate a nearby minnow pond. Tracks that are built in the traditional "oval" shape include Homestead and Dover. Prior to its reconfiguration in 1997, Atlanta also conformed to this layout.

Paper clip ovals
One sub-classification of the traditional oval shape is the "paper clip" oval. The layout consists of two long straights, connected by two sharp, tight-radius turns, giving the track a shape resembling a paper clip. The courses are usually very challenging, and usually offer little banking, making the turns very slow and tight to maneuver. Notable "paper clip" ovals include Loudon and Martinsville.

Tri-ovals
Tri-ovals have become preferable to track builders as they offer superior sightlines. A tri-oval resembles an isosceles triangle with rounded-off corners. The circuits typically have a straight backstretch, while the main straightaway where the pit area and most grandstands are located, has a "tri-oval" curve (sometimes characterized as a fifth curve) that makes the mainstretch skewed.

The 1990s race track construction boom of 1 ½ mile tri-oval shaped tracks has given these tracks a "cookie-cutter" label. Chicagoland is unique among tri-ovals, in that it has a slightly curved backstretch, and an overall more rounded shape.

Doglegs
Some oval tracks have minor variations, such as kinks or doglegs. A "dogleg" is a defined as a soft curve down one of the straights, either inward or outward, which skews the oval into a non-sysmetric or non-traditional shape. Phoenix is one example of a dogleg shape. While the extra curve would seemingly give the oval 5 turns, the dogleg is normally omitted from identification, and the ovals are still labeled with 4 turns. Trenton Speedway had a unique right-hand dogleg, giving the track what was called a "kidney bean" shape.

Quad-oval
A tri-oval with a "double dogleg" is often called a "quad-oval". The first such was Charlotte built in 1960. The shape has become a signature for SMI, which owns the other two major quad-ovals, Atlanta and Texas.

The quad-oval is very similar to the tri-oval in sightlines and layout. One specific feature is that the start/finish line segment actually falls on a straight section, rather than along a curve.

D-shaped oval
Another common shape variation is the "D-Shaped oval." Similar to a tri-oval, the D-Shaped oval has a straight backstrech, but a long, sweeping frontstrech, giving the circuit a layout resembling the letter "D." The shape originated with a pair of "sister tracks" built in the 1960s: Michigan and Texas World. Auto Club Speedway, built in 1997, was built to the same configuration. Two short tracks, Richmond and PPIR were also designed to this standard.

Concentric oval tracks / Legends oval
Some facilities feature more than one oval track of different sizes, often sharing part of the same front straightaway. The now defunct Ascot Speedway featured 1/2 mile and 1/4 mile dirt oval tracks, and Irwindale Speedway which features 1/2 mile and 1/3 mile concentric paved oval tracks. Pocono Raceway once had a 3/4 mile oval which connected to the mainstrech, and circled around the garage area.

In 1991, Charlotte Motor Speedway connected the quad oval start/finish straight to the pit lane with two 180 degree turns, resulting in a concentric 1/4-mile oval layout. The 1/4-mile layout became a popular venue for Legends car racing. The name "Legends oval" was derived from this use. They have also seen use with go-karts, short track stock cars, and other lower disciplines. This idea was adopted by numerous tracks including Texas, Atlanta, Kentucky, Las Vegas, and Iowa which has a 1/8 mile version.

Combined road course
A "Combined road course" is an oval track racing facility that features a road course in the infield (or outfield), that is usually linked to the oval circuit. This type of course allows the facility to be used for road racing. A typical combined road course consist of the oval portion of the track, utilizing the same start/finish line, and same pit area, but a mid-course diversion to a winding road circuit in the infield. At some point, the circuit leads back to the main oval, and completes the rest of the lap. On some of the faster ovals, a chicane is present on long back-straights, to keep speeds down, and create additional braking/passing zones.

Combined road courses combine the high speed characteristics of ovals with the technical precision of road courses. It allows road racing disciplines the unique experience of being held in the "stadium style" atmosphere of an oval superspeedway. Numerous combined road courses saw widespread use with sports cars in the 1970s and early 1980s, but their use has since diminished considerably, since most lack the desirable topography of natural road courses. Since 1962, the 24 Hours of Daytona has been one of the most notable races held on a combined road course.

Roval
The term "Roval" has been used to loosely describe an oval track with an asymmetrical, unusual, or oblong shape, or atypical features. While these courses still technically fall under the category of ovals, their unique shape, flat corners, hard braking zones, or increased difficulty, often produces driving characteristics similar to those of a road course. Pocono, a triangular course with three distinct, widely varying turns, is often characterized as a "roval."

Banking
Oval tracks usually have slope in both straight and in curves, but the slope on the straights is less, circuits without any slope are rare to find, low-slope are usually old or small tracks, high gradient are more common in new circuits.

Circuits like Milwaukee Mile and Indianapolis Motor Speedway are approximately 9° tilt in curves are considered low slope, superspeedways like Talladega has up to 33° tilt in curves, Daytona has up to 32°, both are considered high inclination. Charlotte and Dover are the intermediate with the highest bank, 24° tilt. Bristol is the short oval with up to 30°.

Pack racing
Pack racing is a phenomenon found on fast, high-banked superspeedways. It occurs when the vehicles racing are cornering at their limit of aerodynamic drag, but within their limit of traction. This allows drivers to race around the track constantly at wide open throttle. Since the vehicles are within their limit of traction, drafting through corners will not hinder a vehicle's performance. As cars running together are faster than cars running individually, all cars in the field will draft each other simultaneously in one large pack. In stock car racing this is often referred to as "restrictor plate racing" because NASCAR mandates that each car on its two longest high-banked ovals, Talladega and Daytona, use an air restrictor to reduce horsepower.

The results of pack racing may vary. As drivers are forced to race in a confined space, overtaking is very common as vehicles may travel two and three abreast. This forces drivers to use strong mental discipline in negotiating traffic. There are drawbacks, however. Should an accident occur at the front of the pack, the results could block the track in a short amount of time. This leaves drivers at the back of the pack with little time to react and little room to maneuver. The results are often catastrophic as several cars may be destroyed in a single accident. This type of accident is often called "The Big One".

Comparison with road racing
Oval track racing requires different tactics than road racing. While the driver doesn't have to shift gears nearly as frequently, brake as heavily or as often, or deal with turns of various radii in both directions as in road racing, drivers are still challenged by negotiating the track. Where there is generally one preferred line around a road course, there are many different lines which can work on an oval track. The preferred line depends on many factors including track conditions, car set-up, and traffic. The oval track driver must choose which line to use each time he approaches a corner. On a short track in a 25 lap feature race, a driver might not run any two laps with the same line. Both types of racing place physical demands on the driver. A driver in an IndyCar race at Richmond International Raceway may be subject to as many lateral g-forces (albeit in only one direction) as a Formula One driver at Istanbul Park.

Weather also plays a different role in each discipline. Road racing offers a variety of fast and slow corners that allow the use of rain tires. Paved oval tracks generally don't run with a wet track surface. Dirt ovals will sometimes support a light rain. Some tracks (e.g., Evergreen Speedway in Monroe, WA) have "rain or shine" rules requiring races to be run in rain.

Safety has also been a point of difference between the two. While a road course usually has abundant run-off areas, gravel traps, and tire barriers, oval tracks usually have a concrete retaining wall separating the track from the fans. Innovations have been made to change this, however. The SAFER barrier was created to provide a less dangerous alternative to a traditional concrete wall. The barrier can be retrofitted onto an existing wall or may take the place of a concrete wall completely.