Safety of car recovery (and trucks on circuits)

[Richard]

Lets say an F1 car weighs 750kg, say 5g lateral force = 3 750kg. That's trivial compared to highway loadings.

The real reason that you see ripples on public roads is simply bad design or construction. Perhaps a wearing coarse that is too soft, failure of base coarse, or failure of sub base.

[strad]

If I'm not mistaken this subject is right in Ciro Pabón's wheelhouse.

[Andres125sx]

Lets say an F1 car weighs 750kg, say 5g lateral force = 3 750kg. That's trivial compared to highway loadings.

The real reason that you see ripples on public roads is simply bad design or construction. Perhaps a wearing coarse that is too soft, failure of base coarse, or failure of sub base.

Again, I´m talking about a different problem. I´ve never said sub base or bad design does not cause bumps, that is obvious. But I´m talking about a different cause that may also cause bumps.

You (and Ciro) are talking about vertical loads, for that problem it´s obvious that subbase, design and wet soil are the cause. But I´m talking about horizontal loads. In that case the subbase or soil has no relevance (assuming they´re ok of course), it´s the pavement, the last layer of asphalt what must take those loads, so asphalt cohesion (I think that´s the correct term) is the relevant parameter. Cohesion wise porous asphalt cannot be as resistant as flat/compact asphalt because of pores. Those pores are air substituding asphalt/resin, so cohesion is inevitably reduced

Hope it make sense

[strad]

Been giving this some thought since it dawned on me that this is exactly what my city is doing in an effort to clean up the runoff water before it gets to the bay.
Here the water flows thru the permeable asphalt, then is directed thru what for lack of a better term is a drain field then into water gardens that clean the water before reaching the bay.
So.. My thinking is that it would require tearing up the tracks to install this crushed rock and gravel drain field which would be very expensive ,then to have huge underground tanks, somewhat like septic tanks to catch and hold the water before directing it to yet another drain field to keep it from turning the area around the track into a marsh. Yet more expensive.
So, while it seems on the surface like a great idea, it seems the substrata of crushed rock and gravel would not be ideal for under the asphalt of a racing circuit and the expense would be massive.
I'm sure Ciro might know much better than I, but I don't think we could convince track owners to fund it and obviously the FIA isn't gonna come off a dime.
Better I think would be to have competent drivers. You must realize that in past times, drivers had to cope with three or four different road constructions and surfaces on one track. You also should remember that the "tracks" used to be formed by blocking off country roads to create the track. Remember, what you all now know as Stavelot used to be the turn off to go to the town of Stavelot.

[rscsr]

Lets say an F1 car weighs 750kg, say 5g lateral force = 7 500kg. That's trivial compared to highway loadings.

The real reason that you see ripples on public roads is simply bad design or construction. Perhaps a wearing coarse that is too soft, failure of base coarse, or failure of sub base.

interesting that no one has seen that awful calculation error: 5x750!7500 it is 37500.
Anyway, I've heard Alex Wurz say every year that the bumps in the breaking zones (especially in China) are increasing every year due to the hard decelarations.

edit: embarrassing mistake in the calculation

[GitanesBlondes]

I'm sure Ciro might know much better than I, but I don't think we could convince track owners to fund it and obviously the FIA isn't gonna come off a dime.

In a reasonable world, FOM would have to pick up the tab to repave all of the circuits as they're the only ones with enough money. However that would never happen as that is not their purpose.

Such a request would invariably fall to the circuits. This would in turn have most circuit owners all running to their local or state governments looking for a subsidy to get this done. Problem is, as with most everything F1 related, the taxpayers wind up footing the bill for a load of sh*t.

It's sad. The fans themselves are the one's paying for a lot of these safety upgrades and renovations at the end of the day, only they don't realize it. It's all parlor tricks performed to try and lift the money out of state coffers, and to transfer it to FOM. State money comes from you the taxpayer. Pretty good way to piss money away as there's no real value to be had by hosting a grand prix in the 21st century as things are presently constituted.

All these circuit renovations and hosting fees come out of your pocket eventually, but only one entity is getting their money's worth, and that's at the top of the food chain.

[notsofast]

there's no real value to be had by hosting a grand prix in the 21st century as things are presently constituted.

Combine rFactor with Twitch, and there you've got the future of F1. Watch Hamilton and Rosberg duke it out. No need for safety cars or JCBs.

[Richard]

Andres: Ripples from lateral loads and rutting from lorry loads both depend on shear deformation of the wearing course. In both cases the asphalt is squeezed into a deformed shape. That deformation is dependent on the size of the load as well as the number of loadings. Ciro and I are saying it is not a problem for the sort of loading we see in F1, the numbers are smaller than highway loading.

Strad - The circuits will already have drainage along the track edge. So the easiest method is to overlay a porous wearing course (50mm) on top of the current surface and the new porous overlay will drain into the existing channels. The channels might need to be adapted but fundamentally it's the same drainage system in terms of the below ground pipes.

[Andres125sx]

Andres: Ripples from lateral loads and rutting from lorry loads both depend o shear deformation of the wearing course.

Agree on this

In both cases the asphalt is squeezed into a deformed shape.

But a very different way Richard

With a vertical load from a truck, asphalt is compressed, and transmit that load to the lower layer (base), and this to the lower one (subbase), and this to the lower one (soil), so it doesn´t matter if that load have been distributed through all those layers, if the soil is soft because of the rain, it will descend making all the layers descend causing a bump. So in this case the ahphalt is resisting nothing but a compression, wich actuallly doesn´t cause huge deformations, it´s the soil what is deformed and all the layer over it collapse and descend with the soil causing the bump

But with hoirzonal loads from brakings, the load is not transmitteed anyway, it´s the asphalt itself what must resist that load or it will do the same as if you brake over a carpet, bend and/or break. That´s the short term, but the long term will also have consequences, deformation/corrugation, or creation of bumps. Asphalt is a bit elastic, this means it´s moved on each braking, really little movement so it´s not visible, but with the long term those movements cause corrugations and bumps

That deformation is dependent on the size of the load as well as the number of loadings. Ciro and I are saying it is not a problem for the sort of loading we see in F1, the numbers are smaller than highway loading.

No, they´re much higher. The vertical loads are much lower as you two have perfectly explained, but the horizontal ones are much higher because of the higher braking power of racing vehicles. Vertical loads are distributted to the soil thanks to the base and subbase, but horizontal loads, even if they´re lower than vertical ones, are not transmitted, it´s a shear stress asphalt must take. And it´s asphalt cohesion what must be enough to resist this stress.

Imagine a road with no resin at all, just gravel. A truck can pass over it perfectly (as we do on buildings to avoid mud), but if a bike apply full brakes, it will drag the gravel. Much lower load than the truck, but it´s much more difficult for the road to resist that horizontal load than the vertical one. Same with asphalt

As real world experience show:

I've heard Alex Wurz say every year that the bumps in the breaking zones (especially in China) are increasing every year due to the hard decelarations.

I´ve also heard that on spanish broadcasting, don´t know if it was DeLa Rosa or Gene, but I´ve heard it. I remind I instantly though about those bumps on MX tracks, I had never thought that could happen on asphalt tracks, and that comment made me think about this for a good part of the race

As you probably know, I love analysis, and if it´s something I´ve seen and suffered myself on real world (MX bumps) and also see it on F1 races, I can do it for hours

If I´m able to explain it in english is a different matter but a challenge too, and I also love challenges

[autogyro]

The flexible surface I suggested ten years ago would work well but of course is too expensive.
In this latest crash however, so far no one has answered my questions.

Did the team radio the driver with the information that the recovery vehicle was on track?
Was there sufficient time for the team to respond?
Perhaps the latest restrictions on radio use added to the accident.

[Richard]

Andres - I give up.

[Blanchimont]

The flexible surface I suggested ten years ago would work well but of course is too expensive.

How exactly would your solution look like?

In this latest crash however, so far no one has answered my questions.

Did the team radio the driver with the information that the recovery vehicle was on track?
Was there sufficient time for the team to respond?
Perhaps the latest restrictions on radio use added to the accident.

http://www.f1fanatic.co.uk/2014/10/08/2 ... ranscript/
We don't know yet, what the team said to Jules in the time before the accident. The transcript only shows what was actually aired and there where no messages to Bianchi, although i'm sure that every driver was immediately notified by his team about the yellow flags.

https://mediacru.sh/tWTt5ZvVQ0oN
This shows that the team had a complete lap to tell Bianchi about the accident of Sutil, as Bianchi was just ahead of Sutil. That's two minutes to get to the radio, a bit less until the double yellow message appears.

The latest radio restrictions do not hinder the teams to provide information on security, i don't think that's a factor in this accident.

[Ciro Pabón]

.. But I´m talking about horizontal loads. In that case the subbase or soil has no relevance (assuming they´re ok of course), it´s the pavement, the last layer of asphalt what must take those loads, so asphalt cohesion (I think that´s the correct term) is the relevant parameter. Cohesion wise porous asphalt cannot be as resistant as flat/compact asphalt because of pores. Those pores are air substituding asphalt/resin, so cohesion is inevitably reduced...

Again, I don't know where to start.

I'm not going to explain pavement design in one post. I'm just going to explain that cohesion is an electrical attraction between molecules. There is no cohesion in asphalt. Cohesion is what creates droplets of water.

Cohesion, Wikipedia. Notice the guy grinning: trolling or smiling?


Asphalt resist compression, shear and bending moments, as any material in this Satan presided Earth.

You claim, contrary to decades of research in asphalt design, that the top of asphalt layers take most of the horizontal stress.

Simple: no.

This is a technical forum, sorry for trying to say things... well, technical.

Maximum horizontal stresses on asphalt occurs at the BOTTOM of the asphalt layer and the larger horizontal stresses are not caused by horizontal loads but by vertical loads


I promise I won't reply to anything that is not related to porous asphalt as a way to avoid aquaplaning and, thus, avoid situations in racing when soaked road surfaces are the main cause of accidents.

Porous asphalt can:

• Reduce spray levels from vehicle tires in wet conditions
• Prevent aquaplaning
• Improve skid resistance in wet conditions
• Improve night time wet weather visibility

Of course:

• Pores can get clogged
• Asphalt can become more dense under heavy loads.

These things happen under heavy loads, not typical of F1 cars, because racing cars weigh little.

The main reasons to avoid porous asphalt use are, as mentioned:

• Statu quo
• Economic factors.

Beautiful and safe roads: the reason why racing exists and a prerequisite


So, I'm all in for a better pavement management to avoid accidents like the one of Bianchi and for transferring some money from TV to circuit safety and maintenance, so safety can be enhanced when new technical solutions for circuits are available.

Unlike cars, that are enhanced continuously, circuits are not, money for their enhancement is sparse and that's a situation that cannot be sustained in the long run.

[strad]

thanks Ciro =D>

[Ciro Pabón]

Your welcome, old friend.

I'd love to mention what was said at Grand Prix's article on this accident:

... it has also been suggested that F1 and the governing FIA are reluctant for the official footage to be seen because it might implicate the sport's authorities amid the controversial circumstances surrounding Bianchi's crash.

Questions are being asked about the rain conditions, the fading light, the pre-race discussions about re-scheduling to avoid typhoon Phanfone, the waving of green flags near the crash site, and whether Charlie Whiting should have deployed the safety car when Adrian Sutil's incident brought out the recovery vehicle.

... Separate to the circumstances of the crash, however, is a discussion about arguably the last remaining true vulnerability when it comes to F1 cars -- the drivers' exposed heads.

Have we found a good technical solution to aquaplaning and head hits?