On lap 43 of the Belgian Grand Prix Lewis Hamilton made a small mistake at the Pouhon corner. He grabbed an armful of oversteer and ran wide losing a few seconds in the process. ITV Commentator, Martin Brundle, noted how lucky Hamilton was that he had been able to utilise the new tarmac run-off area at that particular corner. Previously there had been gravel at Pouhon and had that still been the case in 2007, Hamilton would not have finished the race.

Tarmac run-off areas are the latest development in circuit design and have only been around since the turn of the century. Asphalt started replacing gravel after Michael Schumacher’s leg breaking accident at Silverstone in 1999.

The idea of a gravel-trap is to slow down a car once it has left the circuit by using friction. However, Formula One cars have flat bottoms and in many cases simply skip over the loose surface. This was evident in Schumacher’s crash because he was unable to control the Ferrari whilst it bounced towards the barrier. If there had been asphalt instead of gravel at Stowe corner in 1999, Schumacher would have been able to regain control of his car and avoid the wall.

A more recent example of this was Lewis Hamilton’s qualifying crash at the Nurburgring. His McLaren flew across the gravel after a wheel failure and Hamilton shot straight into the tyre wall. He would have been able to avoid the heavy impact if there had been tarmac run-off at his disposal.

In many cases, asphalt is a safer equivalent to gravel and that is why it can now be found almost everywhere.

The biggest advantage of tarmac over gravel is that it won’t flip a car if it spins. There is nothing for the tyres to dig into and nor is there anything for the rollover hoop to catch if the car goes upside-down.

Another advantage of tarmac run-off is that it promotes overtaking. Drivers are able to take more racing risks if there is no punishment for running a little wide. It is easy to have a lunge at someone if there is asphalt available when the move fails. Some drivers even use tarmac run-off to their racing advantage like Hamilton did against Alonso at turn one last weekend.

Although asphalt is now rapidly replacing gravel on circuits all over the world, it is not always the most effective way to stop a car during an accident.

Tarmac run-off is totally useless in the wet because a car will aquaplane straight over it. A great example of this was the European Grand Prix when rain caused havoc at turn one. Six drivers aquaplaned off the circuit and the tarmac run-off did nothing whilst the cars only started decelerating when they hit the gravel.

Tarmac can also be troublesome when a wheel becomes dislodged because the asphalt only provides friction against the tyres. If you have a big enough accident to remove a wheel then you might be better off skidding into gravel because the asphalt wont always do enough to slow you down.

Despite this, Lewis Hamilton is likely thankful that asphalt is now in place at Pouhon because it probably saved his race. Spa is the latest circuit to adopt the new safety trend, adding tarmac run-off to the La Source, Pouhon, Stavelot and Bus Stop corners this year.

It is quite fitting that Spa Francorchamps is the most recent track to add tarmac run-off areas because it was there forty years ago that F1 safety first began.

In 1966 Jackie Stewart crashed during the Belgian Grand Prix and consequently started his campaign for circuit modifications.

The old Spa Francorchamps was fourteen kilometres long and was so large that it could be wet on some parts of the track whilst totally dry elsewhere. This was the case in 1966 when Stewart crashed on the first lap with six fellow drivers. He hit a rain shower out the back of the circuit and aquaplaned at the superfast Masta Kink. He crashed wildly through a barbed wire fence and a garden shed before ending up in a ditch. It was a massive accident and Stewart was trapped in the wreckage whilst fuel leaked all over him.

Jackie was perhaps lucky that both of his BRM teammates went off at exactly the same moment, following in his wheel tracks. Graham Hill and Bob Bondurant were able to help Stewart in the absence of all medical staff and eventually got him out of the car.

Jackie survived the accident but it had a long lasting effect on him, and on Formula One. He instantly started campaigning for safer racetracks and kicked off the process that made Formula One as safe as it is today.

The first thing he did was demand Armco fencing at all circuits. This seems like a fairly basic request but in the 1960’s only Monza and Monaco had extensive barriers. It seems crazy to think today that most circuits only used fences to protect spectators and not the drivers.

Jackie Stewart was instantly maligned by for trying to make Grand Prix racing safer. Other drivers thought he was softening the sport and ruining the challenge of Formula One. This frustrated Jackie because he was only asking for barriers at dangerous corners, but he pushed for years and years before Armco fencing eventually became the norm.

The next innovation in circuit design was catch fencing. This was essentially a system of chain link fences that would slow down a car as it crashed through the various layers. They became increasingly popular in the 1970’s and in theory they worked brilliantly. An out-of-control car would slow gently as it hit each layer.

Unfortunately catch fencing was not so good in practice. The fences had to be supported by solid poles and these could prove fatal on impact.

It was also hard to service. Each fence had to be totally rebuilt after a car crashed through it, and that certainly wasn’t something that could be done in a hurry. Catch fencing was rarely seen after the 1970’s and by 1985 it was outlawed.

Gravel-traps had arrived by that stage.

Initial gravel-traps were fairly rudimentary but these days they are scientifically designed to slow down a car as effectively as possible. Most gravel-traps are roughly 25cm deep and will be filled with stones about a centimetre in diameter. This particular design has been developed because it provides the best friction against a spinning car. Gravel-traps are also strategically located and shaped for best effect.

The question now is whether tarmac run-off is an improvement on this concept.

Owners of the Paul Ricard circuit in France believe they have found the answer.

Paul Ricard has massive tarmac run-off areas but they are coated with tungsten that creates an abrasive surface like sandpaper. The closer you are to a barrier, the more abrasive the surface becomes. If you ever see a photo of Paul Ricard you will notice the colour coded stripes that run alongside the circuit. The red stripes are more abrasive than the blue, and are so coarse they could ruin your tyres if you drove over them.

Paul Ricard is currently the only racetrack in the world with this characteristic and it likely represents the future of circuit design.

Who knows what Jackie Stewart would have thought of that forty years ago?

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