Pit Stops Considerations

Here are the vital pieces of information the teams will take into consideration:

• The way you qualify. Because fuel cannot be added or subtracted between Saturday qualifying and the race, the cars have to qualify with enough fuel on board to do the first stint of the race. Obviously a car planning to three-stop can qualify lighter than one on a two-stop strategy. The team needs to trade off the importance of qualifying position with the optimum race strategy.
• The weight of fuel. This varies according to how dense the fuel is, but the regulations specify the density must be between 0.725 and 0.77kg per litre. The largest tanks hold around 150 litres and brimmed to capacity will therefore weigh around 120kg.
• The amount of lap time this costs at the track in question. A half-tank car is quicker by around 2.4 seconds per lap around Suzuka than a full tank one, whereas over the similar distance of a Monza lap – with long straights and not many corners – the difference is only around 1.6 seconds. Suzuka therefore errs towards a two-stop strategy, Monza a one-stop.
  
• The consumption of fuel. How much fuel (and therefore weight) needs to be put into the tank and how much the car sheds as it races tends to be higher at a track with lots of accelerating, braking, and use of the lower gears. The Hockenheim track, as revised from 2002, induces heavier fuel consumption than any other on the Formula One calendar. Although lap times at the track are only averagely sensitive to weight changes, the big reduction in weight (because of the high fuel consumption) means that the total effect is large. It’s therefore another track favouring a two-stop strategy. At the other end of the pole is Nurburgring where there is relatively gentle fuel consumption but where lap times are highly sensitive to weight. The net result is very similar, and again a two-stop is favoured.
  
• Your qualifying position. If your grid position places you in an attacking position – meaning that you need to overtake other cars – you are more likely to opt for an aggressive two-stop strategy, even if the maths tells you that a one-stop is quicker. If it’s a track where pretty much everyone can be guaranteed to be on the same number of stops, you have a choice: depending on whether your strength is early or late in the stint, you can either short-fuel for the first stint, using your lower weight to pass cars and then hope to pull out enough of a time cushion before you stop to keep you ahead after they have stopped. Or you might choose to take on board as much fuel as you dare and hope you can keep up with cars that are lighter early in the race; when you stop later it will take less time as you will not spend as much time refuelling to get you to the end.
  
• Other cars and overtaking opportunities. The more pit stops you make, the more you are at the mercy of traffic – of getting caught behind slower cars after your stop but before they make theirs. At a track with plenty of overtaking opportunities this is less of a consideration than at a place like Monaco where passing places are few and far between. The timing of your stop might also be influenced by traffic – for example, you might come in earlier than planned so as to avoid encountering a bunch of lapped cars.
  
• How the brakes are wearing. At some circuits – such as Imola, Montreal and Monza – brake wear is extreme. A heavier fuel load places extra strain on the brakes, due to the extra weight and momentum that they are working against.
• The skill of the driver. The handling balance of the car changes a lot from the beginning of a stint to the end. This change will be larger the longer the stint. Some drivers can cope with handling changes better than others, so it is something that has to be taken into account.