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