The most striking part of the Paul Ricard
circuit, host of the French Grand Prix, is its seas of blue and red run off areas. The
circuit boasts the supposed safest racetrack facilities in the world, but massive expanses
of tarmac run off have often been criticised in modern racing. So how did we get here,
and are they the best solution? We’ve previously looked at barriers and
their roles in protecting drivers and others when cars accidentally leave the track at
high speed. Another key part of controlling accidents ae in the areas around and between
the actual track – that is the run off areas in all their many guises.
The point of a run off area is to increase the distance between the track and anything
the cars might hit at high speeds. Increasing this distance gives the car more
time to slow down so it either hits the barrier at a much slower speed, or it doesn’t hit
the barrier at all. For a long time, circuits used ‘natural’
style run off areas of grass and gravel. Grass was an easy solution as it tended to
already be growing around the track anyway. Unfortunately, grass is very slippery, especially
in the wet. Compared to the track surface, stopping power of grass can be over three
times weaker than a dry track and twice as bad as a wet track.
You keen ecologists out there might know that grass grows in soil, which has a tendency
to soak up rainwater and turn it into a bog under extreme weather as we discovered when
the British Grand Prix was moved to April for one ill-judged year.
Grass is not easily repairable if ruined by cars running off track – in fact you tend
to just have to throw some more seed on it and… wait. Either that or re-turf the whole
area. Grass is mostly used now in areas where cars
are not likely to fly off the circuit at high speeds, like the edges of straights or the
insides of corners. Though artificial grass is also used sometimes
on the skirts of tracks and around kerbing it is not without its own problems. It can
often be more slippery than real grass and can be ripped from the track by the extreme
forces of an F1 car. Gravel traps were put into the areas where
a car was likely to fly off the road: at the end of long straights, around high speed corners
– that kind of thing. About a quarter of a metre deep and filled
with stones a centimetre or two across, gravel traps were implemented as a better deceleration
tool than the useless grass. They too are much less grippy than the actual
track surface though, and one of their main problems remains that cars at high speed can
skip across the surface of the gravel, barely losing speed at all.
In 1999, Michael Schumacher ploughed straight across the gravel trap at the end of Stowe,
hit the wall at over 100 miles per hour and broke his leg.
See, if a car is going straight ahead, it’s very hard for the gravel to slow the car down
because the individual stones in the gravel trap are not bound to each other and are very
small, so when you brake on these stones, you drag them with you and they barely absorb
any of your momentum. On tarmac, all of the frictional force is
going into the ground and you’re getting maximum resistance from the track on your
wheels. On gravel, these surface stones will resist
very slightly but get dragged with you. They’ll be resisted slightly by the next layer but
only just, and so on and so on, so the gravel can only resist your momentum very weakly,
and very gradually. Gravel traps can be raked perpendicularly
to the expected direction of a car’s travel, which adds some undulation to the gravel – in
effect making tiny walls that will be able to push back against the car and absorb this
forward energy. When gravel traps can be effective is if a
car starts to spin or pitch slightly. In these instances, the car’s movement will start
to have a directional component into the gravel and its kinetic energy can be dissipated into
its depths, with many, many stones absorbing the kinetic energy of the car.
In fact, gravel will stop a rolling or spinning car much faster than tarmac tends to.
However, a gravel trap is also much more likely to pitch a car into a roll in the first place.
If a car starts sliding or spinning sideways through the gravel, it can create a wall of
gravel which trips up the car and sends it into a roll. Which is undesirable.
Gravel also has the unfortunate problem of ‘beaching’ a car. This is when the tyres
can’t get enough grip on the gravel to get moving again. Similarly to before, the surface
layers of gravel do not provide enough friction to transfer momentum to the rest of the car
to get it moving. Instead they just fly out from under the wheels.
This can be made doubly worse if the car ends up shifting the gravel beneath it such that
the car floor rests on a mound, lifting the wheels out of the gravel slightly so they
can not push into the ground with enough force to drive into them.
So gravel can roll and beach a car, which is bad because you don’t really want to
eliminate or damage a car for a simply mistake. They also end up requiring a lot of tending
to as they need to be re-raked or refilled if cars make a mess of them. Cars can also
drag the gravel out onto the circuit which ends up being a spin or puncture hazard to
cars going past at race speed. And above all, they don’t even slow the
cars down that well. So they’re a bit rubbish in a lot of ways.
So we come to tarmac run offs that come with their own set of compromises.
First and foremost, they are the safest form of run off.
They are grippy, stable and predictable as they are essentially made of exactly the same
material as the race track itself, so a car can brake, steer and yes, even crash as it
was designed to. However, this means that drivers treat them
like an extra bit of track, so running off the circuit becomes no big deal.
Worse, it can even become advantageous to leave the circuit. If the track is surrounded
by more tarmac, mis-braking into a chicane and over-shooting has earned you a shortcut.
Overcooking it into a fast corner and running wide on exit means you can keep your foot
down and actually go faster than if you took the corner properly by taking the ‘wider
line’ you made for yourself on the outside. The problem becomes how to police drivers
who don’t stay within the track limits. Yes, it’s good that cars can keep running
if they make a mistake and run wide, and great that their chances of having a big accident
are minimised but how do we make sure that drivers don’t use what is essentially a
safety feature to gain a track advantage? Some drivers have said it’s stupid that
circuits are made such that going off track can be faster than staying on the track, but
to them I say – stay on the track. That’s your job. It may be faster to straight line
a chicane but it’s also easier to pick up a football and run into the goal. But it’s
against the rules – so don’t do it. What a weird complaint.
One solution was installing big sausage kerbs like speed bumps along the edge of the track
and across chicanes at problem zones. That’s definitely a deterrent but comes with the
problem or damaging cars that run across them and potentially launching them into the air
if hit at speed, which is exactly the opposite level of safety that a run off area is supposed
to provide. In some cases, the FIA tried flattening kerbs
on the exit of corners but installing them with sensors that detected if cars had run
wide. That’s fine but then you’re left with the task of punishing drivers with some
kind of time penalty every time they go over the limits. It’s better for drivers to be
hit with the penalty on track at the time of the incident and get it over with. That’s
what some people like about gravel traps – they serve instant punishment for mistakes.
Some tracks, most noticeably Yas Marina and Paul Ricard have areas of super-grippy surfaces
on their run offs that are even better at slowing the cars down but are very heavy on
tyre wear. This makes for easy flat spotting and rubber damage if you brake across these
zones, which is certainly a penalty though a potential race ruiner if it forces you into
an extra pit stop. The best solutions in my opinion have been
the mandatory return routes. These require drivers to take a specific detour
if they go off track at particular points. These could be in the form of having to navigate
a tight chicane of polystyrene boards, as is the case for those who overshoot the opening
chicane at Monza. You could also force a driver to stay inside
a line and/or drive around a bollard before being allowed to return to the track, as is
the case for those sliding off track at turns two at both Catalunya and Sochi.
These solutions are nice because you can design a very exact level of punishment into the
return route and drivers can be penalised without damage to the car or risk of retirement.
And once they’ve taken the hit, they can move on with the race and we don’t have
to think about it again. There are those who yearn for more gravel
traps but I think tarmac run offs are here to stay for the long run. And all that matters
now is for the FIA to determine where drivers can take an advantage by leaving the track
and implementing deterrents like return routes where possible and horrible kerbing where