Canadian Grand Prix: The role of track evolution in Hamilton’s victory

Posted on June 12, 2012

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Usually, I’m not big on the effects of track evolution during a Grand Prix. That’s because I can see the effects of the track rubbering in from the data in the opening laps (between 3 and 9 laps at most races) and then the behaviour is pretty much constant for the rest of the race. However, in Canada, the data shows big track evolution up to about half-distance. How quickly the cars were able to use their optimum grip (so the effects of track evolution became unimportant) made a big difference – especially in the case of the race winner.

These track evolution effects explain quite a few things; the significantly higher degradation in the first half of the race, the pace of Perez and Vettel on the supersoft option tyres at the end, and how Hamilton got his 3s lead. That the evolution was significant is easy to demonstrate. Fuel-corrected the pace of Vettel on the options in the last few laps was a full 1.7s faster than his pace in the opening laps. Yes, there is an effect of tyre conservation, and a possibility of fuel saving, but even still this is a very big difference. This is reasonably consistent across cars who used the same compound of tyre early and late in the race, except in the case of Button, who only gained 0.4s.

The race traces of Hamilton, Alonso and Vettel are shown in the chart below. On underlying pace, there is nothing to choose between the model fits for each. What is different is how quickly they reach this pace – in the highlighted part. Hamilton is much closer to the race pace than the others straight after the stops – he was 0.6s faster the lap after he overtook Alonso, and this gap gradually reduced over 7 laps until their pace was the same. But by this time, the gap was there. Part of this is tyre warm up, but the effects are similar for cars with different age tyres at this stage of the race – so it seems most likely that there is an effect of the Ferrari needing more rubber down to get the best from the tyres.Vettel was able to use the grip more quickly than Alonso as well, but not enough to get past (mainly because the Red Bull is slow in a straight line). You can make arguments that Alonso was saving tyres for a one stop, but it was never a winning strategy.

On the chart I have added the model fits for Hamilton and Alonso. Hamilton laps at the same fuel corrected pace in the final stint as at the end of the second stint. I have also added the fit of Alonso on the assumption that his tyres held out to the end. Hamilton gets him with about four to go. It would have been harder to get past (and Vettel as well), sure, but I don’t see that Alonso would have held on. He would have been second, but Hamilton was (barring errors) always going to win. I am surprised that Vettel did not stop earlier (within a couple of laps of Hamilton) as this became apparent very quickly. What would have been interesting then would have been if Vettel had gone for the option tyre (Hamilton was on the prime) as my best guess of the pace gap is order 0.6-0.7s per lap in the second half of the race. That could have won Vettel (or indeed Alonso) the race. I admit to being surprised when Lewis took on primes for the final stint – it could have cost.

In the chart below I have added a fit for if Vettel repsonded to Lewis taking on prime by taking options on the following lap based on his pace in the final laps. Now that would have been close. Not sure that the Red Bull straightline speed would have got him past, though…

Out of interest, I have also done a fit for the degradation of Alonso’s tyres in the final stages. It’s a simple quadratic fit, but it looks pretty good. All it shows is that from lap 57 Alonso got slower by about 0.2s each lap – by the end of the race this was a loss of 2.5s on the pace he was running when Hamilton stopped. He lost something of the order of 18s on where he ‘would have been’. I make it that it would still have been better to stop even with only 4 laps to go if he took option tyres. It’s amazing that he didn’t stop when Vettel did – or even the lap before as his tyres began to go first. Personally, I don’t see this loss of 0.2s each lap of pace as a cliff – it’s not sudden, but gradual, and there is plenty of time for the team to respond. Red Bull responded late, but they responded. Ferrari did not.

So another great race, and unlike Monte Carlo there’s a huge amount of interesting data – not least on the races of Grosjean and Perez. I’ll look at them in the next article, and I’m also planning to do a regular check of Friday pace against race pace as again it was a pretty good reflection of the race (note the Force India slump) despite the difference in temperature.

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