In motorsports racing, there is a concept called the racing line. This is defined as the optimal path around a race course that will allow the racer to complete a lap in the least possible time with the highest possible average speed. The racing line is a function of the track's layout, the capabilities of the specific vehicle type, and the physics of motor racing.
Because the physics involved generally propel vehicles along a certain path, course designers can predict and extrapolate where a vehicle is likely to depart the course. As a result, run-off areas are placed in these specific locations, such as around the outside of a corner as opposed to alongside a straight-away.
Run-off areas are an important safety feature of modern motorsports parks and road courses. They are the basis for several other safety features, such as gravel traps and air fences, which could not be placed anywhere, or would be ineffective without a proper run-off area.
When interviewed about track features, many top professional racers mention the availability, design, and size of run-off areas. Knowing that a track is safe gives them added peace of mind and allows them to push the limits further, as they have less fear of the consequences of making a mistake. In short, the most important safety feature of a track—outside of personal equipment or vehicle features—is the quantity, size, quality, maintenance, and race-type specific configuration of its run-off areas.
In modern racing leagues, if a track does not have adequate safety preparations including proper run-off areas, racers will often threaten to boycott events. Racing leagues also maintain safety standards when selecting venues. To prevent strikes and attract lucrative professional events, track managements often make substantial financial investments to add or improve safety devices.
Making safety improvements makes financial sense to a track's management. It leads to greater demand from event promoters and larger events, which increase gate revenues and advertising revenues. Popularity with professional leagues also corresponds to higher usage by non-professionals and hobbyists. If top racers do not feel a track is safe, they may pressure their league to avoid the venue, or the league may choose not to schedule events until requisite changes are made.
There are different types of run-off areas, including gravel traps, AstroTurf, and tarmac. Gravel traps are designed to slow down vehicles by dissipating their kinetic energy. However, the configuration of these areas must be specific to the type of racing taking place.
A notable example occurred during the 1993 Italian motorcycle Grand Prix at Misano, where World Champion Wayne Rainey suffered a broken back after crashing into a gravel trap. In that instance, the gravel trap had been raked in an effort to more quickly dissipate the kinetic energy of off-course cars. This change was unfortunately left in place for the motorcycle race, contributing to the injury. AstroTurf is also utilized as a run-off surface alongside gravel and tarmac.
Track safety has evolved through the concerted efforts of racers and supporting organizations, moving safety from an afterthought to a top priority for sanctioning leagues, sponsors, and team owners.
The introduction of the air fence is a key example of this evolution. The air fence performs similarly to a commercial vehicle air bag, but it is pre-inflated rather than inflating upon impact. By acting as a soft, energy-absorbing barrier, air fences can be placed over hard obstacles around tracks that racers might encounter in an accident. These devices are especially important and widely used in motorcycle road racing.
The quality of a track's safety features, including run-off areas, holds enormous economic sway. Tracks must be competitive in their safety facilities to lure events from the most popular racing leagues. By making a venue safe and feature-rich, park management can increase revenues from gate fees and sponsorship deals for advertising space on track property, such as walls, bridges, and infield grass. Because popular leagues have more television viewers, the rates a facility can charge to advertisers are higher when the track is safe enough to host major events.