How a race turns on many decisions

The Belgian Grand Prix was a race where a lot of decisions needed to be taken, many on the hoof, due to the uncertain weather conditions, which had prevailed throughout the weekend.

It is a fascinating case study in how teams and drivers pick their way through a race, based on the evidence of Friday practice, best guesses about what the other teams will do and lots of instinct.

Big decisions on Saturday had a knock-on effect to Sunday. Timing the final qualifying run was everything and Mark Webber and Red Bull got it just right, putting on a new set of soft tyres at the right moment, just before rain fell, to set the pole lap.

Fernando Alonso wasn't so lucky, he saved his new set of tyres for later in the session and rainfall prevented him from improving. This was bad luck. But Alonso was in the position of only having one set to decide when to use, because he had used a set of new tyres earlier in Q2, which he would not normally do, but had been concerned about making the cut.

So the result was that the car which had set the fastest times on Friday and looked a contender for victory, started the race tenth on the grid as a result of a series of decisions.

The following day, during the race, he and the team were forced into a quick decision after he was hit by Rubens Barrichello at the end of the opening lap.

Going into the weekend, Alonso had said that the driver who gambles would win, but he was forced into a gamble by this early stop. It had started raining and they gambled that the rain would fall for a long time, so fitted a set of intermediate tyres. It didn't rain any more and he was back in for slick tyres three laps later. This dropped him to 20th place, another opportunity to win a race or at least get a podium, gone. Although luck played a part here, Alonso would be the first to admit that some of the decision making this year has cost him.

Once the race settled into a rhythm, the key decision for front runners was when to make the first stop. They wanted to delay it as long as possible, because they were getting diminishing performance from the tyres, but they wanted to hold out as long as possible in case more rain fell so they could go straight onto the wet or intermediate tyre.

Adrian Sutil and Force India were again very competitive at Spa.

Sutil had qualified 8th, especially as he had been in the same boat on new tyres as Alonso. Force India are at the level of competitiveness where Q3 and the top ten are the target and any places they make up after that after that are a bonus. So he did well to qualify ahead of Alonso in the circumstances.

Sutil was running fifth as the teams started to think about making that first pit stop. He had started on the soft tyres he had qualified on, knowing that some cars around him were on hards, which might have turned out to be tactically superior.

The hard tyre was not as easy to warm up and not all the drivers could get the speed out of them.

The decision the teams make is based on constant monitoring of their own cars and the opposition using the timing loops every 100 metres around the circuit. Rather than rely on information at the end of each of the three sectors, the strategists are assessing the situation every few seconds. If they see the tyres on their car starting to go off they know it's time to pit and by following the progress of other cars they can decide what is the best tyre to go on to.

Mercedes had started the race on the hard tyre, hoping it would last long enough to see them to when the rain came. They were behind Sutil on the road at the time he stopped.

They had suffered a lot of degradation and so when Sutil stopped on lap 21 he lost the place to the Mercedes, but was two seconds a lap faster and able to pass them easily. They finished behind him in 6th and 7th places.

Sutil's pit stop started the trend for the other front runners, who pitted soon after.

With this in mind, it would have been very interesting to see what Rubens Barrichello might have achieved on his 300th Grand Prix start as he too started on hard tyres from 7th place on the grid. He would likely have finished ahead of Sutil and may even have challenged Massa for fourth.

The final decisive moment was near the end when the rain started to fall and yet the teams wanted the drivers to stay out on slick tyres as long as possible. This tactic almost spelled disaster for Lewis Hamilton, who went off the road, but was able to keep going.

There were several reasons why the teams were so reluctant to bring the cars in; we had seen on Friday that the intermediate tyres were too soft for Spa and were going off after two laps. The rain started falling 12 laps from the end and that would have been much too long for those tyres. So the decision to pit was based on a risk assessment; which was more risky, leaving the drivers out on a wet track on slick tyres or bringing them in with the risk that it doesn't rain hard enough, and/or the intermediates go off rapidly and you then face an uncertain few laps, maybe another stop, which could cost you your result?

Amazingly, they concluded that it was safer to stay out on slicks.

However, calm, rational risk assessment is one thing, human emotion is another. When Hamilton went off, all the strategists got cold feet and decided to abandon their plan and bring their drivers in !