Pit stop
In motorsports, a pit stop is a pause for refuelling, new tyres, repairs, mechanical adjustments, a driver change, as a penalty, or any combination of the above. These stops occur in an area called the pits, most commonly accessed via a pit lane which runs parallel to the start/finish straightaway of the track and is connected to it at each end. Along this lane is a row of garages (typically one per team or car) outside which the work is done in a "pit box". Pit stop work is carried out by the pit crew of up  to twenty mechanics, depending on the series regulations, while the driver often waits in the vehicle (except where a driver change is involved or in motorbike racing). The term is also used generically to describe a short break in a journey. Location and terminology. Depending on the circuit, the garage may be located on pit lane or in a separate area. In most series, the order of the teams' pit boxes is assigned by points standings, race results, or previous qualifying results before the start of the race. In NASCAR and in INDYCAR's Indianapolis 500, typically pit assignments are  made after qualifying, with the fastest qualifiers choosing their pit stall first. Most North American circuits feature a pit lane with a number of pit stalls (typically 30–50) and a pit wall that separates the pit lane from the infield, with the garages (if used) on a separate road in the infield. In races where there are different series racing together, each series has its own separate garage or are parked in their own area. Circuits in other parts of the world (used in Formula One) typically have the individual garages open directly onto the pit lane through the team 's assigned pit box. In American English, it is common to drop the definite article and just refer to "pit road", whereas in British English one would always refer to "the pit lane". A further difference is that in British English, the term "pit box" is universally used, whereas in American English, one would say "pit stall". It is important to note that in NASCAR, a pit box is a tool (see below), though there is a definitive term used for them. Purpose. Where it is permitted, refuelling is often an important purpose of a pit stop. Carrying fuel slows  down a vehicle, and there is often a limit on the size of the fuel tank, so many races require multiple stops for fuel to complete the race distance in the minimum time. Changing tyres is also common, to permit the use of softer tyres that wear faster but provide more grip, to use tyres suitable for wet conditions, or to use a range of tyres designated by the rules. Teams will aim for each of their vehicles to pit following a planned schedule, with the number of stops determined by many factors, such as fuel capacity, tyre lifespan, and  the trade-off between time lost in the pits versus time gained on the track due to the benefits of pit stops. Choosing the optimum pit strategy of how many stops to make and when to make them is crucial in having a successful race. It is also important for teams to take competitors' strategies into account when planning pit stops to avoid being held up behind a competitor where overtaking is difficult or risky. An unscheduled or extended stop, such as for a repair, can be very costly for a driver's chance of success, because while they are  stopped for service, competitors remaining on the track are gaining time on them. For this reason, the pit crew often undergo intensive training to perform operations such as tyre changes as quickly as possible, leading to pit stops, for example, as in Formula 1, where the car is only stationary for a few seconds for a regular pit stop. General strategy. In any racing series that permits scheduled pit stops, pit strategy becomes one of the most important features of the race; this is because a race car travelling at 100 miles per hour (160 kilometres per hour) will travel  approximately 150 feet (45 metres) per second. During a ten-second pit stop, a car's competitors will gain approximately one-quarter-mile (400 metres) over the stopped car. However, the car that made the additional pit stop will run faster on the race track than cars that did not make the stop, both because it can carry a smaller amount (and thus lower weight) of fuel, and will also have less wear on its tyres, providing more traction and allowing higher speeds in the corners. In racing series where teams have their choice of different compound tyres, the lower  tyre wear may be enough to allow the team to choose to use a tyre with a softer rubber compound that provides increased grip at the expense of faster wear; going longer between stops may even cause enough wear on the softer tyre to cause the tyres to fail. Because of this, race teams plan a pit strategy prior to the start of every race. This is a schedule for each car's planned pit stops during the race, and takes into account factors such as rate of fuel consumption, weight of fuel, cornering speed with each available tyre compound , rate of tyre wear, the effect of tyre wear on cornering speed, the length of pit road and the track's pit road speed limit, and even expected changes in weather and lighting conditions. The pit strategy does not just include a schedule of "when" pit stops will happen; it also includes what service and adjustments are scheduled for each pit stop, particularly in endurance racing, where scheduled changes of wear-limited parts such as brake pads may be planned for specific points during the race. The pit strategy is calculated carefully so that the amount of time to be  given away to other competitors in pit stops is balanced by the time gained while on the track, resulting, theoretically, in the shortest possible time to cover the scheduled distance. However, a team's pit strategy is not a fixed, immutable thing; it is subject to change during the race to take into account the unpredictable events that happen in every race. In road racing, for example, if the weather changes from dry to rain, teams will be forced to recalculate their pit strategy based on the unscheduled stop to change from dry-weather "slick" tyres to treaded wet-weather  tyres. Safety car periods often see mass pit stops by many teams, hoping to take advantage of the slowed pace to reduce the ground lost to other teams while making pit stops; this forces teams that do so to immediately recalculate their pit strategy to optimize it for the remaining race distance after the stop. Even when a team chooses not to take advantage of the opportunity to stop during a full-course caution, it can still result in significant changes to pit strategy; under caution, the cars run at a reduced speed that results in greatly reduced tyre wear  and fuel burn for a distance travelled. Depending on the circumstances, this may be enough for a team to gain more by choosing not to pit, hoping that the reduced fuel burn and tyre wear will allow them to make one pit stop fewer than the other teams, allowing them to gain distance and time on their opponents. At tracks noted for frequent full-course cautions, teams may even plan their entire race strategy around this, using a suspension and aerodynamic setup suited to short sprints instead of extended runs to gain positions in the short bursts of green-flag  racing, and planning their pit strategy on the assumption that cautions will extend their fuel mileage and tyre wear enough to make fewer stops than would otherwise be needed to complete the race distance. Services performed. During a scheduled pit stop, the team's pit crew services the vehicle as quickly as possible, completing a number of different services. The most common services performed are refuelling (where permitted) and changing tyres. Other services performed in routine pit stops include removing debris from radiator air intakes, cleaning the windscreen, and making adjustments to tyre pressure, suspension settings, and aerodynamic devices to  optimize the vehicle's performance for the current conditions. In endurance racing, scheduled driver changes and brake pad replacements are also considered "routine" service when done as part of a scheduled pit stop. An unscheduled pit stop may see other services performed; because unscheduled stops are often due to damage or mechanical problems, they may include emergency repairs and replacement of parts. In some forms of racing, a team may be ordered to bring a vehicle into the pits as a penalty and either drive through the pit lane at the maximum permitted speed or remain stationary in their pit  box for a specified period of time. During this time no services can be performed. Formula One. In Formula One, mid-race refuelling has been banned since 2010, and cars make pit stops with the primary purpose of changing tyres. Teams sometimes also make adjustments to the front and rear wings and perform minor repairs, most commonly replacing the nose and front wing assembly. A pit stop typically takes 2 to 3 seconds to complete. Red Bull Racing holds the current world record for the fastest pit stop, with a 1.82-second stop performed at the 2019 Brazilian Grand Prix  on Max Verstappen. Pit strategies generally call for between one and four scheduled stops, depending on the circuit. The drives between pit stops are commonly known as 'stints'. When the car is approximately one lap away from making its stop, the team's pit crew will set up fresh tyres and all needed pit equipment. Because of the overhead pneumatic rig, the team may have all pit mechanics in position prior to the car's arrival, with the exception of the rear jack man. Unlike almost all other forms of racing that feature routine pit stops, Formula One rules limit  teams to a single pit crew for the mandatory two cars entered. Most other racing series that feature routine pit stops permit each car its own pit stall and crew. Therefore, teams must stagger their pit schedules so that only one of their two cars is in the pits at any given time; otherwise, one car must wait for the other car to finish services. However, with proper timing or in special conditions (for example, in the period immediately after the safety car being called out), it is possible for teams to pit both cars on the same lap without  losing significant time; this is known as the 'double stack' strategy. This allows both of the team's drivers to race on equally fresh tyres, preventing either from having an advantage over the other, and helps the team hide the relative performance between two cars to other teams when only one car is in the pits. One strategy commonly used in Formula One pit stops is the 'undercut' involving two cars battling for track position. In this strategy, the car behind makes an earlier pit stop than the leading car; if successful, the car behind should be able to utilize  the advantage of having fresh tyres to reduce the lead of the car they are attempting to overtake. If the gap between the two cars is reduced to less than the time lost in a pit stop, when the leading car pits, the leading car will exit the pits behind the car which pitted first. This strategy is especially effective when the leading car is stuck in traffic and/or if the car behind has clear track to push on, but can be negated if the car behind gets stuck in traffic after their early pit stop or is unable to  drive fast enough to neutralize the advantage of the leading car. Similarly, there is the reverse (but less common) strategy of the 'overcut', where the leading car stays out on their older tyres longer and laps fast enough to maintain or even extend their advantage over the car behind—this strategy may be successful if the leading car's tyres are still in good shape when the car behind pits, sufficiently so that the leading car can push without being overly limited by tyre degradation, or if the car behind gets stuck in traffic, thus negating their ability to utilise  their fresher tyres to their advantage. Refuelling. Refuelling, now banned in F1 races, was permitted from the 1994 season to the 2009 season. During this period, a pit stop involved about twenty mechanics, with the aim of completing the stop as quickly as possible. Stops generally lasted for six to twelve seconds, depending upon how much fuel was put into the car. However, if there was a problem, such as a fuel pump failing or the engine stalling, or repairs having to be made, it could take much longer. Cars were fuelled at a rate of more than 12 litres  per second. This was accomplished by a fairly complex closed system that pumped air out of the car's fuel tank as the fuel was being pumped in. Since fuel was a significant portion of a car's weight, teams varied the amount of fuel loaded into a car at any given stop (and prior to the race) and thus vary the number of pit stops. The most common strategies seen were one-stop and two-stop strategies; two-stop strategies were employed to increase the car's speed/improve lap times to catch cars ahead, whereas one-stop strategies  were used to gain time and track position to cars ahead with the advantage of one fewer pit stop. However, teams could and sometimes did opt for unorthodox pit strategies with multiple (3+) pit stops, as was employed by Ferrari and Michael Schumacher with four stops at the 2004 French Grand Prix, which he eventually won. As refuelling was a potentially hazardous situation, the mechanics wore fire-resistant multi-layer suits and flame-resistant gloves, long underwear, balaclava, socks and shoes, which had to meet the guidelines set by FIA Standard 8856-2000. Formula One pit crew roles. Deprecated  roles Formula E. For its first four seasons, pit stops in Formula E served the primary purpose of changing cars—since FE cars did not yet contain the necessary electric charge to complete a full race, drivers needed to switch cars during the race. With the exception of repairing damaged tyres, no other mechanic services were allowed to be performed on the cars during the pit stop. Prior to the 2017–18 season, the rule and scoring system in Formula E allowed for some unusual pit stop strategies. Previously, drivers scored one point for setting the fastest lap in the race  regardless of finishing position (or whether they finished the race at all); hence, a driver with no chance at finishing in the point-scoring positions for whatever reason could switch cars, wait for the prematurely right moment to come out of the pits and set the fastest lap of the race. Notably, this was seen in the 2016 London ePrix, when championship contenders Sébastien Buemi and Lucas di Grassi utilised this strategy after their first lap crash rendered them otherwise unable to score points; Buemi ended up with the fastest lap, winning the Formula E 2016 drivers' championship as a  direct result. For the 2017–18 season, Formula E's rules were amended to restrict the additional point for fastest lap to drivers finishing in the top 10 only, rendering the aforementioned strategy obsolete. For Formula E's fifth season (2018–19), new cars were introduced which had batteries capable of completing the entire race distance; thus, such pit stops were no longer used during races, other than in the event of repairing damage. Plans are underway in Formula E to bring back pit stops in a race, but this time it would be not to change tyres or the car but  to charge the car using high speed electric charging stations. The details are yet to be finalised. NASCAR. Crew chiefs lead the pit crew during pit stops in addition to coaching the driver during the race. Pit crew members were once the mechanics on the racecar, but most teams feature individuals dedicated to pit stops only, and often former collegiate or professional athletes are used for pit stops. Former NFL player Tim Goad is regarded as the first former professional athlete involved in a pit crew, as a jackman. Nonetheless, some pit crew members work with the team in fabricating  or designing the race cars during the week while training for their "pit job" on the weekends. Teams have built full training centers similar to that of professional athletes for their pit crews. There are a number of penalties that can be incurred on a pit stop. The driver must keep the car below the pit road speed from the pit entrance to the pit exit; the speed limit is typically 35–55 mph, depending on the size of the track. Teams can be penalized if the car is serviced outside of the designated pit stall, if the car drives over  an air hose, or if any of the old tires are not on the pit wall side (usually left) of the vehicle's centerline before the car leaves. The most common penalty for a pit infraction is a "drive-through": the driver must enter the pits again, under the green flag, and maintain the pit speed limit for the entire length of pit road. If a car stalls, the pit crew may provide a push start, but the car cannot be pushed beyond three pit stalls ahead of its own, or beyond the pit exit light and steward at  the end of pit road. Pit stops are timed from the moment the car stops in its pit stall until service is finished and the car leaves the stall. A pit stop for four tires and fuel can last 12 to 16 seconds, and a stop for two tires and fuel may take 5 to 7 seconds. Late in a race, a team may only need a small amount of fuel to make it to finish; this is called a "splash and go" and may take as little as 2 to 3 seconds. These times depend upon any suspension adjustments  performed and the quality of the crew. NASCAR Cup Series team pit strategies vary widely, depending on the track. Fuel is generally a more limiting factor than tire wear, and the phrase "fuel window" or "pit window" is used to indicate the maximum number of laps possible with a full load of fuel, assuming continuous green flag conditions and a small reserve. The window is used to calculate (or recalculate after a stop) the minimum number of pit stops required to complete the race. The road courses on the schedule may see as few as two scheduled stops; oval race  tracks generally see between four and six scheduled stops. Races at short tracks such as Bristol Motor Speedway and Martinsville Speedway are short enough to be completed with only two scheduled stops for fuel, but teams plan on more stops due to rapid tire wear and significant loss of cornering speed on worn tires. If one team pits for tires and is considerably faster (between 1 and 3 seconds per lap), then teams will usually follow quickly to avoid losing time. Pit strategy can play a significant role in the outcome of a NASCAR race, perhaps more so than other  racing series. Under caution, most teams use similar strategies to avoid being caught alone, typically following the leader's decision to stay out or pit, but sometimes teams will deliberately pit "off-sequence" if they feel they can gain an advantage later. Race tactics can affect strategy as well. Late in a race, drivers can reduce throttle input to save fuel at the cost of slower lap times, but by doing so they can stretch their pit window to the end of the race and skip the final pit stop. A late caution can force teams to make a tough  call: Stay out on worn tires, or pit and give up track position. The green-white-checker rule can cause headaches, as it can potentially extend the race an unknown number of both green-flag and yellow-flag laps. Furthermore, strategy can be determined by qualifying position. A team that qualifies in the top six positions will have the best choice of pit stalls, most often choosing the first, last, or a stall with an opening either in front of or behind that one. A team that qualifies deeper in the field will have a greater opportunity to be stacked  behind cars during a pit stop, slowing them down. IndyCar Series. In the IndyCar Series, a pit stop is a more complex operation than in NASCAR, but far less so than in Formula One. Rules permit six mechanics over the pit wall during a stop. The pit rules and procedures have origins in USAC National Championship racing. The spare fuel for IndyCar competition is stored in large pitside fuel tanks. Each team's tank is filled to a specified volume of fuel, depending upon the race distance. Teams are also given a certain allotment of spare tires sets, likewise owing  to the race distance. All of the spare tires are pre-mounted on wheels before the race. During a routine pit stop, the tires are laid out beforehand, and three of the four tire changers are pre-positioned before the car enters its pit stall. The fourth tire changer, whose responsibility is the rear tire on the far side of pit road from the pit wall, does not take his position until after the car arrives, due to a rule against having the car run over the feed hose for the impact wrench used to change the tires, and a  prohibition of using an overhead boom to support air hoses. As a result, the outside rear changer also serves to wave at the driver to inform him of where his pit box is while holding the air hose up. As soon as the car comes to a halt, the first step, taken while the fourth tire changer assumes his position, is for a mechanic to activate the car's built-in pneumatic jacks. A pressurized air hose is inserted into a receiving nozzle at the rear of the car, under the rear wing. Previously, this device was inserted on the  side of the car, but for safety reasons, the location was moved in the 2000s. At the same instant, another crew member begins the refueling process. A fueling hose is inserted into a socket (called the "buckeye"), allowing a gravity-fed hose to refill the car's fuel tank. The fuel hose has a built-in vent/overflow hose as part of the mechanism, an invention of the mid-2000s. Previously, a second "vent hose" was utilized, but it was phased out to improve safety. Simultaneously, the four tire changers remove the wheels and install the new ones. IndyCar wheels are  affixed to the hubs with a single lug nut, making it easier and faster to change them. After the tire changes are complete, the front tire changers may use manual adjusters to adjust the angle of the car's front wing, remove debris from air intakes, or make other minor repairs. While the service is being completed by the over-the-wall crew, another crew member behind the wall may use a stick to offer the driver a refreshment. After the tire changes are complete, the air jack hose is removed, dropping the car to the ground. However, the driver  usually must wait additional seconds until the refueling is complete. The right front tire changer (who is usually also the crew chief) signals the driver when the stop is complete. Before the car departs its pit stall, a crew member must squirt water to wash any excess spilled fuel from the fuel buckeye; this is usually done with a pressurized water hose by a crew member behind the pit wall. Under normal conditions, a routine stop for an IndyCar team lasts between six and ten seconds. IndyCar teams are permitted to set their own pit strategies. Super Formula. In Super  Formula, Japan's top-level single-seater series, a total of six mechanics are allowed to work on a car. Of these six, three have fixed roles: the lollipop-signalman, the refueler, and the fire-fighter. They are forbidden from undertaking any other function during the pit stop. The remaining three mechanics are responsible for all other operations, most notably jacking up the car and changing the tyres. The general strategy is to have the three free mechanics operate on the car in an assembly-line-like manner, moving around the car between different stations. Because of the limited personnel , teams often come up with creative solutions to decrease pit stop times. For example, some teams employ an automatic front jack, which is placed in front of the car as it stops. Mechanics might also jump over the nose-cone of the car to save time getting to the other side. With the automatic front jack, a Super Formula pit stop takes between ten and twelve seconds; even without the automatic jack, pit stops can be completed in as little as fourteen seconds. Endurance racing. In the various forms of sports car endurance racing, pit stops are a more leisurely  affair, but no less important than in other forms of racing. While stops take longer, much more routine maintenance is scheduled during such pit stops, needed to keep the car running for as long as twenty-four hours; this includes major aerodynamic changes to deal with the changing temperature in such a long race, and replacement of certain wear-limited parts, such as brake pads. Due to the fact that the race is scheduled to last a certain length of time rather than a specific distance, pit strategies are generally not designed to be synchronised with the race distance, but  rather to happen on a schedule based on the car's requirements for routine service. Under the rules of the Automobile Club de l'Ouest (ACO) only five mechanics are permitted to work on the car. One man is permitted to fuel the car; all fuelling must be completed before any other service occurs. The other four mechanics on pit lane at any given time are typically two tyre changers and two tyre carriers, each of whom handles his task on only one side of the car. Automatic pneumatic jacks are used, integrated into the car itself. At all times the  car's engine must be shut off during the stop, and may start only when the stop has concluded. IMSA allows only four mechanics to service a car during a pit stop. One crew member will refuel the car while the other three are responsible for changing tyres and operating the pneumatic jacks. A fifth crew-member must serve as the team's designated firefighter and must stand ready in the pit stall with a fire extinguisher while the car is being refuelled. A sixth crew-member may assist in a driver change. Neither the firefighter or driver's assistant  may perform any additional service to the car. Unlike the ACO, IMSA does not force crews to wait for fuelling to complete before changing tyres, and does not require the car's engine be shut off during the stop. In endurance racing, driver changes are mandatory; the shortest endurance races are scheduled for four hours, one hour longer than the longest nonstop time permitted behind the wheel. During a pit stop with a driver change, the new driver and a driver change assistant are permitted into the pit lane. The assistant, who may not do any mechanical work on the  car, is tasked with helping the current driver out of the car, removing or swapping driver seat inserts, helping the new driver into the car, and helping the new driver tightly fasten his safety harness and connect his various helmet connections to the car's systems, including the two-way team radio and the drink bottle used to stave off dehydration. A routine pit stop with no scheduled maintenance and no driver change generally lasts from thirty to forty seconds. With a driver change included, that time increases by about ten seconds. Should there be significant scheduled maintenance, such as  changing brake pads, the stop can easily last well over a minute. Unlike most other forms of racing, the practice of "double-stinting" or even "triple-stinting" tyres is commonplace in longer races; tyres hard enough to withstand the rigours of racing in the heat of the daytime may be so hard that they do not wear significantly during the nighttime hours. In a race where this is an issue, significant time can be gained by choosing to leave worn tyres on the car during the first stop after they were put on the car; if the temperature drops low  enough, teams may even be able to go two pit stops without changing tyres.