View Single Post
Old 15 Sep 2008, 08:31 (Ref:2290626)   #10
PVDA
Veteran
 
Join Date: Dec 2002
Australia
Melbourne
Posts: 3,011
PVDA should be qualifying in the top 5 on the gridPVDA should be qualifying in the top 5 on the gridPVDA should be qualifying in the top 5 on the grid
Trouble is you guys aren’t looking at what I’m try to say.

Yes PI has made many changes to various run off areas which has reduced the number of car vs. wall hits in some areas. . I can remember PI back before it closed in the late 70's and there wasn't much between the spectators and the race cars in some areas but a simple people fence but the problem still remains that when they rebuilt the site in the 80’s they surrounded the entire complex with earth filled tyre walls which although cheap to build are not the best option.

There are many different types of collisions in motorsport with may variables from the speed of the vehicle to the angle of the hit. Tyre bundles in low speed head on collisions are good at reducing vehicle damage and driver injury BUT a glancing blow, like Andy Jones yesterday into any form of tyre wall can result in a vehicle digging into the wall and this throws the vehicle anywhere.

Lets look at a couple of scenarios of a theoretical collision with a wall at say 45 degrees which is probably what Jones did yesterday.

Car leaves circuit and heads for a smooth concrete wall.
Car hits wall at angle which damages that corner of the car and the momentum then causes the car to slide along the wall until it runs out of momentum and it comes to a gentle stop (gentle by motorsport standards).
This car probably has damage to the entire one side of the car but because there was no sudden stop or High G change in direction driver injury is kept to a minimum. In Jones’s case yesterday he would’ve ended up somewhere near the gravel trap before the hayshed. Denosaur suggested a gravel trap prior to the wall which is an excellent idea but you still need something to deflect the car if it gets through the gravel.

Now lets do the same with an earth filled tyre wall.

Car leaves the circuit and heads for a tyre wall.
Car hits the tyre wall and depending on exactly where it hits one of the following "could" happen (tyre walls aren't smooth and there are gaps & differing amounts of give between different tyres even if conveyor belts are used);

1. car digs in and bounces out from the wall possibly into the path of other cars. Depending on the angles involved the G forces could be severe.

2. car digs in and destroys the wall and the car comes to a violent sudden stop with extremely high G forces for the driver.

3. car digs in and is forced upwards by the impact and goes over the wall or rolls along it. This option is possibly the best for the driver as there's no sudden stop but will trash the car. This looks to be what happened to Jones yesterday from what I saw on the TV.

The above is long winded but it's not easy to describe the forces involved without some detail and there are a lot more possible scenarios that you could apply it all depends on exactly where the car hits the tyres , the speed, the angle of the hit and the design of the vehicle involved.

Everyone thinks it's better to hit nice soft tyres compared with hard concrete but it's not the initial hit but what results from it you must consider. There are places for tyre bundles (proper bundles chained together not earth filled tyre walls) but this is in lower speed head on situations not high speed glancing blows like we saw yesterday or in the past at PI & other tracks around the country.

Race track safety is an ongoing cost that has to be met by circuit owners as a part of operating a race track and involves negotiations between sanctioning bodies (at PI they have cars & bikes to consider) and the circuit owner as standards change and improve as we learn more.

Phillip Island is considered safe as it would meet the minimum requirements to hold a track licence for both CAMS & MA events but that doesn't mean they cant do more gradually to ensure they exceed the minimum requirements to make it even safer.

If you don’t believe what I’ve said in my scenarios above contact your local track safety committee member and have a long chat to them about the merit of concrete vs. earth filled tyres as I have in the past. There are all sort of formulas for determining the size of run offs depending on vehicle speed and the size and depth of gravel traps which fill volumes on the FIA web site.

I stand by my belief, that I've had since the mid 90's, that Earth Fill Tyre walls should be phased out of motorsport tracks.
PVDA is offline  
Quote