Road Surface Effects

[delacf]

I've been looking for information on Internet and I found this about micro/macro texture. This is interesting:



In my opinion we can expect a higher coefficient of Sliding friction implies a higher peak of coefficient of friction.

Cheers

[zonk]

+1 thank you

[ubrben]

That's a nice plot. What's the source?

Ben

[delacf]

Enjoyneering:

http://onlinepubs.trb.org/onlinepubs/nc ... p_w108.pdf

I'm reading it and looks great

Cheers

[zonk]

Although people talk about ‘asphalt’ tracks, asphalt is only one component of the track surface. Asphalt itself is a thick, sticky mixture of hydrocarbons – molecules made of hydrogen and carbon atoms. The first asphalt users got their materials from concentrated deposits in the Earth. These natural deposits were created from petroleum crude oil that rose to the surface. Crude oil is a mixture of many different types of hydrocarbon molecules that range from very light molecules like methane (CH4) and propane (C3H8) to much heavier hydrocarbons with 100 or more carbon atoms. Heat from the Sun vaporized the lighter hydrocarbon molecules, leaving a tar-like material composed of the heaviest hydrocarbons. In the early 1900’s, this process was sped up and moved indoors to petroleum distilleries, which separate crude oil into lighter weight fuels like LP gas, liquid fuels like kerosene, gasoline and diesel fuel, and heavier lubricating oils. What is left over – literally the bottom of the barrel – is asphalt.
Asphalt has two dominant characteristics: It is waterproof and it is really, really sticky. Asphalt’s waterproofing ability is why it was used as early as 6000 BC for shipbuilding. The Egyptians used asphalt as a preservative in the mummification process. The Arabic work for asphalt is mûmîa, which is almost mummy. Stickiness is why we have prehistoric animal skeletons in the LaBrea tar pits, and why asphalt was used as mortar in early building projects. Those two qualities together explain why about 80% of the asphalt in the US is used for making roadways. Asphalt is also the dominant material used in NASCAR tracks. Bristol and Dover are concrete and the corners at Martinsville are concrete, but the rest of the tracks are asphalt.
More properly, these track surfaces are asphalt concrete. Asphalt per se is the sticky stuff. Asphalt mixed with aggregate – crushed stone and gravel – is asphalt concrete, which is what is used for track surfaces. The asphalt and aggregate are heated and mixed together. Heating makes the asphalt less viscous so that it can be pumped through tubes and spread, and also evaporates any water left in the mixture. The asphalt concrete mixture is deposited on the road, leveled, and then compacted with a steamroller. If you look at an asphalt roadway, you often can see the individual asphalt-coated rocks.
The composition, condition and temperature of the asphalt play a major role in racing. Aggregate can vary from small pebbles to inch-sized rocks or larger. The type of aggregate impacts the durability and the roughness of the track. Freshly laid asphalt concrete often has sharp edges from the aggregate poking up and these tracks – like Atlanta Motor Speedway – tend to be very fast because they produce a lot of grip. As they wear, the edges of the aggregate become less sharp and some of the asphalt binder wears away, exposing a little more of the aggregate. The tracks usually lose a little grip and the speeds get a little slower over the years.
Indianapolis, which was last repaved in Fall 2004, is an extremely rough track. The television commentator Larry MacReynolds called it as ‘a cheese grater’. A rough track gives you a lot of grip, but takes quite a toll on tires. Every time a car makes a lap, it leaves a little bit of tire on the track. The rougher the track, the more tire lost on each lap. The upside is that the rubber scraped from the tires coats the track surface and fills in spaces between the aggregate. This rubber coating produces additional grip and mitigates the wear on the tires.
The advantages of having some rubber on the track is one reason drivers hate rain. Rain washes rubber from the track, leaving it ‘green’. The two Friday practices at Indy were rained out. You may have heard Jeff Burton talking about the importance of having a long Saturday practice so that they could get some rubber on the track. The Speed Channel showed tires worn down to the cords after only 15 or 16 laps on the first runs, but significantly less tire wear on tires from runs after the cars had been out on the track for awhile. NASCAR decided to call two competition yellows to give teams a chance to check tire wear.
The other way the asphalt surface can change is when the temperature changes, and Indy is one of the most temperature-sensitive tracks. Asphalt is a collection of hydrocarbon molecules that can be classified into three general groups: cyclics, aromatics, and aliphatics. Aromatics and cyclics are molecules in which the carbon atoms form rings. They differ in the type of bonding between the carbon atoms (the electrons in an aromatic are delocalized, which means that all the electrons are shared by all the atoms in the ring) and their structure: Aromatics are flat while cyclic molecules are three-dimensional. The first aromatics discovered had a pleasant smell, which is why they got called aromatics. Aliphatics are molecules in which the carbon atoms are arranged in a linear chain.
These hydrocarbon molecules bind to each other, forming the molecular network around the aggregate that gives asphalt its structure. The bonds between molecules are relatively weak, so bonds are constantly broken and re-formed, which is one reason that asphalt concrete changes its shape with time and usage. Those are long-time effects; however, there are shorter-term effects as well.
Bonding changes with temperature. Paraffin is solid at room temperature, softens and eventually turns into a liquid when heated. The temperatures at which these transitions happen are determined by how the molecule is put together. For example, octane is an aliphatic molecule with eight carbon atoms. Cyclooctane has the same number of carbon atoms, but they are arranged in a ring instead of a straight line as in an octane molecule. The melting point of octane is -57 °C (-70.6 °F) while the melting point of cyclooctane is 14.59 °C (58.2°F) How the atoms that make up the molecule are attached makes a huge difference in their properties.
When the track warms, some of the hydrocarbons change how they are bonded. Aliphatic molecules soften first. The effect on the track should be evident from the fact that ‘aliphatic’ literally means ‘oily’. Drivers talk about the ‘oil in the track coming out’ when the track warms. More oil means less grip. One explanation for why Indy is more temperature sensitive than other tracks is that its asphalt has a larger proportion of aliphatic compounds relative to other tracks.
Most tracks have greater temperature sensitivity right after repaving. Just as Mother Nature creates asphalt from crude oil by removing more volatile (more easily vaporized) molecules, over the course of a year or a few years, a new track will change as the volatile components are removed. This is why drivers usually are skeptical about the quality of racing on freshly paved tracks. Concrete, by the way, has much less temperature sensitivity, so there shouldn’t be as great concern about going to Bristol’s newly re-surfaced track in a few weeks.
The engineers and scientists that study asphalt concrete are trying to make this material more durable and less sensitive to temperature changes. For example, adding rubber or rubber-like molecules to the asphalt binder to make it less sensitive to the freezing and thawing that cause surfaces to crack.
While they’re at it, I wonder if anyone is working on a track material that would dry quickly after a rain. I’m sure Boris Said, who didn’t get to run in the Pepsi 400 at Daytona in 2007 after qualifying was rained out (despite posting a great qualifying time), would be one of the many people who would appreciate that particular innovation.

[aussiegman]

1. Paul = Paul Haney.

Will look up his published work, however it seems I should treat with a grain of salty skepticism

2. "Mechanical keying" to me just means indentation (personally this is the first I've heard that phrase so perhaps that's where the disconnect is). Literally lack of stiffness. The difference between poking your finger into a sponge and a brick. That parameter however is NOT equivalent to loss rate (or what Pat S I guess is calling asymmetric deformation, in that a local strain doesn't result in a purely elastic or "symmetric" response - there is a loss or "asymmetry" to it). Never said that this parameter is the ONLY thing to "grip" - but it's really big. I would consider it the largest by a good margin. Opinions there may vary. You can most assuredly have a stiff tread rubber that blows the doors off a soft compound because the latter tries too much for "mechanical keying" and not enough for energy loss. Getting the most effective surface area isn't the end game (though it helps if you can get it without trading anything off). And hot race tires may feel sticky to the touch but don't misconstrue that as necessarily a direct attempt to make the rubber act like glue.

Agreed you can have a too soft compound, "for purpose", same as you can have a too hard compound for purpose. But in general this is a durability issue for purpose and you are equating this comparison on the basis of the tyres durability which is where the polymer frequency and Glass Transition temp is relevant. These parameters are directly dependent on the expected time of operation which is the tyres durability.

But as you have said you can have a "stiff tread rubber that blows the doors off a soft compound because the latter tries too much for "mechanical keying" and not enough for energy loss.".

In this case you simply "overheat" the tyre and get blistering and graining or simply melt the rubber off the tyre.. But I really think you NEED to stipulate a time period for this "blowing off of the doors" for real world tyres not theoretical super soft tyres that won't even last a lap .

Fastest timed lap time I would give it to a super soft compound. Over 5 laps I generally would think soft as well, but average over 50 laps yeah sure the harder compound would work better for the longer distance. For the fastest possible lap time and highest CoF number, I'd go with the softer rubber.

Simple examples, the old qualifying tyres or purpose made Time Attack tyres that are arounf from Hankook and Yokohama.

The current Yokohama A050 comes in a super soft, soft and medium compounds across various sizes. The super soft is great (especially when pre-race heat cycled to properly) for the 4 laps it is required to work for when treated right for, however in trading ultimate grip through mechanical keying for energy dissipation it will not run over this expect operational window. Try and push it for 5 or 6 laps and its history and slippery as hell. The Medium will do 15 - 20 laps easily and last a few meets if

Again, it is a balancing act of durability over time against CoF. Time is what generally determines acceptable polymer degradation.

3. As far as the frequency range at which a polymer is excited with regard to force generation, it is indeed related to the small scale surface interaction (high freq.) rather than rotational speed of the tire (very low freq. by comparison). As Ben mentions, Persson's work on this topic is a good thing to read up on.

I'll have a read if I can find anything on line.

4. I don't doubt Pirelli have taken measurements of the track surface. That's easy. I don't doubt that they've made some calculation or prediction of what it will do to their tires. What PR never mentions is what the error bar is on that process. Maybe they have the whole thing down to an incredibly precise science (though given their product performance over the past 2 years I doubt this). In reality though I would expect the error bars are quite large. Wear is not a trivial thing to science out.

The degree of accuracy of the measurements is very very high, well under the millimeter scale. What is open to variation is the black art or actual wear prediction as external effects such as ambient temp, track temp (dependent on cloud cover, time of day, shadows etc), rubbering of the track, other classes running at the event, accidents on track, wind debris (sand/dust) and the list is almost endless. I am sure Pirelli and others get it fairly close but as they get a longer time frame for reference and larger data set, they will get closer to the mark.

5. Interesting that my experience is on the other end of the spectrum when it comes to new surfaces and wear. My experience is that brand new pavement has extremely low wear rates - which is a bad, evil thing.

I don't at all disagree that newer track surfaces are generally much faster than old worn out ones. But I maintain that brand new, you can have very low grip and it's not just down to needing to hose the thing down to wash off "dirt and oil." In my experience the track has to be physically "worked" by hard running over several days or weeks to have any consistent performance... during which time it just gets faster and faster with every outing.

Yeah I have always see new track surfaces wear/degrade my tyres much more than previously seen at the same track. Might be down to car weight, track surface, aero load, tyre construction vs the NASCAR running you're used to working with.

Certainly horses for courses and I understand what you're saying, I've never raced NASCAR so can't comment on what you've seen other that from what I've read and seen in documentaries like Days of Thunder and Talledega Nights. (just jokes )

[Jersey Tom]

But as you have said you can have a "stiff tread rubber that blows the doors off a soft compound because the latter tries too much for "mechanical keying" and not enough for energy loss.".

In this case you simply "overheat" the tyre and get blistering and graining or simply melt the rubber off the tyre.. But I really think you NEED to stipulate a time period for this "blowing off of the doors" for real world tyres not theoretical super soft tyres that won't even last a lap .

Even over just the course of a few laps, with blistering and graining not an issue.

Softness (literally low stiffness) and loss rate often are packaged together, but they are not the same thing.

There are other reasons and cases when stiff or hard rubber is considerably faster over a lap than soft as well. It is just not a global truth that softer is always faster (durability permitting).

[Forza]

The models can only give you an estimation but can not be general for all types of asphalt surfaces. The way a certain tyre compound reacts with a certain surface is based on many factors. The track conditions change over race weekend and over a longer time period even. The friction changes as the components in the asphalt change and wear out. The bitumen and fine aggregate are two components that are crucial for solid asphalt mix structure. Than there are also unique characteristics for every mix that depend on source of stone aggregate, binder (B, PMB - polymer-modified binders) filler, special additives (viatop, rubber, plastics, etc.) and used equipment and pavement techniques. Asphalt mix that are used on race courses are specificity developed based on available materials in the area. What you use is down to what you want to achieve under the regulations for specific category . Also you can't fully predict all the characteristics until you actually run the track with specific tyre/car combination.

Andy Stobart from Bridgestone briefly describes the choice of tyre compounds according to micro and macro roughness of the surface
[youtube]http://www.youtube.com/watch?v=98pJu99NEyI[/youtube]

Also some basic views from Hirohide Hamashima on road surfaces

There are many different surfaces encountered at race tracks around the world. For example, public roads which are also used as race tracks have different design considerations from tracks which are dedicated motorsport facilities. Track surfaces are predominantly asphalt, although we do see concrete at some motor sport venues around the world. Two main track factors determine the allocation of tyre compound for a circuit: the layout and the roughness of the track surface. Layouts obviously vary a lot and the differences can easily be seen. However, there is a big difference between the extremes of the smoother surface circuits we visit, such as Monaco and Montreal, and the more abrasive circuits such as Silverstone and Barcelona. Track surface is not a constant, and over the years the track can change as it ages. As a track gets older, different things happen. For example, the colour of tarmac can often fade, so a new track is more black than an older surface, and the darker surface attracts heat from the sun more than a lighter surface. If a track is used frequently, the surface becomes smoother, but also the bitumen gets worn away bringing the stones to the surface so it can be difficult to predict exactly how we will find the surface when we visit a circuit. Early in a Grand Prix weekend a track surface usually has less grip than it will have after Formula One cars have been running on it. We call the track surface ‘green’ before it has rubbered-in. Some tracks get a lot of motorsport use and the change over a race weekend with these circuits is less extreme than at a track which is seldom used. When the track does not get a lot of use we see a more dramatic change of grip level provided by the track over the race weekend. When a track is resurfaced there are a number of issues. If the track has been resurfaced in its entirety, we have to analyse the new surface and sometimes this means a change in our thinking when approaching that circuit. A freshly laid track often still has oils coming out of it, which presents a slippery surface when it is initially used, especially if it rains. We often see circuits which have certain parts resurfaced, the most extreme example of this being the Montreal track recently, where track problems meant the hairpin was resurfaced after qualifying on Saturday, before Sunday’s race. We do not see this often. Where there are different surfaces over the course of a lap, a driver has to be very vigilant as the grip levels will vary, and this can make for an interesting time behind the wheel. In the wet there are a number of different track surface considerations. Some surfaces give more grip than others when they are wet, and the amount of water drainage a surface allows has a big influence on which tyre can be used, and how well that tyre performs.”

The Formula 1 Mix for Singapore
In Singapore, the high standards specified for racetracks were met by the special asphalt mix Type F1 SBS (Styrene Butadiene Styrene) PMB (Polymer Modified Binder). The mix was developed especially for this application after extensive tests.

This F1 mix contains a polymer-modified binder designed for the extreme conditions of high-speed motor racing and test circuits. The binder features higher viscosity and stiffness, a higher softening point and a lower penetration point compared to mixes used for conventional roads.

As shown in the wheel tracking test, the F1 mix has a higher resistance to deformation than asphalt mixes used in ordinary pavement construction. The dynamic creep test revealed that the road’s permanent resistance to rutting is higher, too. And due to the rough surface texture, the pavement features a considerably better grip.

Special mix for Formula 1 circuits provides better grip
The Formula 1 mix is designated as F1 SBS (Styrene Butadiene Styrene) PMB (Polymer Modified Binder) and was developed for the extreme conditions of high-speed motor racing. The material is 80 percent more expensive than conventional wearing course mix, but provides greater resistance to shear forces and deformation. The Formula 1 asphalt mix was developed by Hanson Buildings Materials and contains a special polymer-modified binder with a significantly higher viscosity. It can withstand high temperatures without softening and displays a low level of rolling resistance. Its rough surface texture also provides extra grip for the Formula 1 racing cars. “You can‘t compare this material with mixes for conventional road construction. Placing it with the pavers was a major challenge for our paving team on account of its high degree of viscosity,” says General Manager of OKP Holdings, Mr. Or Toh Wat.

Strict tolerance of 3mm
According to the strict rules of the FIA, the surface evenness may not deviate by more than 3mm over 4 metres in the transverse direction measured at any random point on the circuit. What‘s more, special regulations apply to road markings on city circuits. These have to be removed at the braking points to prevent the race cars from skidding. The same applies in bends and at blind points of corners so that the drivers are not confused. Paving work has to be completed 90 days before the start of the race in order to allow time for the circuit to be inspected and approved.

Expert know-how for the paving team
OKP Holdings delegated a paving team to the job site in Singapore that has already completed successfully a diverse array of jobs over many years and has a lot of experience working together. Nevertheless, the Grand Prix paving job presented the team with a real challenge. In order to prepare for all eventualities, proven experts in the field were also called in. On the one hand it was Dr. Low Boon Hwee, a materials expert from Hanson Building Materials, the company which had developed the Formula 1 mix, and two applications technology experts from VÖGELE on the other. They have a wealth of experience in all aspects of paving and already provided their expert advice at numerous Grand Prix circuits, including Hockenheim, the Nürburgring and the circuit in Barcelona.

Once the test paving had been successfully completed, the actual resurfacing of the race circuit went smoothly. The OKP paving team was full of praise for their new VÖGELE pavers. Just like the actual race itself, resurfacing of the circuit was done counter clockwise. This means that the Formula 1 racing cars will always drive in the same direction as the special asphalt mix was placed. This minimizes rolling resistance and makes the circuit perfectly prepared for the race.

Paving “hot to hot”
The total width of the circuit is 15m, so that the two SUPER 1600-2 pavers were set up to pave widths of 7.5m each. A condition specified for the circuit was a perfect bond between adjacent strips. In order to flawlessly meet this requirement, the SUPER pavers placed the two strips hot to hot.

Assessment according to the International Roughness Index (IRI)
Once paving was completed, the circuit underwent a pavement condition survey in two phases in order to assess its ride qualities according to the International Roughness Index (IRI). The first inspection took place right after completion of the circuit and the second 6 weeks prior to the race. The IRI was carried out by an independent and accredited laboratory using drill cores. Now the race can start. Not only the paving team involved in the roadworks are waiting impatiently for the moment on September 28, when the red lights of the signal system extinguish and the first Formula 1 race in history starts under floodlights.



Asphalt Mixes for Racing Tracks
Over the years, asphaltic concrete has established itself as the optimal paving material for all racing tracks hosting Formula 1 events. In the focus of these applications primarily are asphalt characteristics referring to the road’s surface properties and ride quality, such as skid resistance and evenness.

Skidding resistance is achieved, among others, by selecting aggregate with a high resistance to polishing. Used as a measure in this context is the Polished Stone Value (PSV). Aggregate with a PSV > 58 contributes substantially to excellent anti-skid properties. Asphaltic concrete is the preferred material for racing tracks as it generally displays a well balanced ratio of mega, macro and micro-roughness due to its aggregate composition with a high content of sand and no omitted-size grain, thus possessing good permanent non-skid properties. The International Roughness Index (IRI) is a standard for measuring pavement roughness. As a general rule applies: the higher the index, the better the pavement’s grip.

As far as perfect evenness is concerned, also a key characteristic of Formula 1 circuits, these projects call for sophisticated machine technology. The machinery, in conjunction with the appropriate asphalt mix, must be able to meet the requirements made on these specific contracts.

Shear strength and resistance to deformation are further properties of the pavement, which for racetracks need to meet far higher standards compared to conventional road construction. On high-speed circuits, the strain on the pavement are not high static or dynamic loads caused by heavy weights, but rather the horizontal shear forces introduced into the pavement by the braking and accelerating action of the 900 HP racing cars. Furthermore, the asphalt must feature high stability in order to prevent deformation in the heat of the high-speed races.

As a binder, bitumen blended with Trinidad Lake Asphalt or bitumen enriched with plastic additives (polymers) proved to be an excellent choice for racetracks. The special polymer-modified binders are perfectly suited to absorbing the extreme tangential forces exerted by the racing cars when braking, accelerating or taking tight bends at high speeds. The binders also feature high elasticity and have strong adhesion properties. Due to their high content of polymers, they are perfectly suited to meeting the stringent requirements made on racetracks in terms of resistance to deformation, aggregate/binder adhesion and flexibility.

Paving First Formula 1 Circuit In India
A demanding circuit distinguishes this newcomer to the Formula 1 racing calendar. The 3-mile circuit with 16 bends, a road varying between 59 and 82 feet in width, superelevations up to 12% and gradients up to 10%, demands considerable driving skill and offers optimum conditions for breathtaking overtaking manœuvres. Oriental LTD's experts opted for technology from VÖGELE in order to deliver top-quality paving results despite these demanding requirements. Aided by the powerful pavers, they built a two-layer crushed-stone base and paved roughly 325,000 tons of asphalt for the circuit and its peripheral areas in the course of the project. The requirements made on the asphalt layers were extremely high in terms of both material quality and paving accuracy. The permissible tolerances for binder content, grain mix and also evenness were far lower than those of German motorways.

Minimum tolerances for wearing course
Particularly stringent demands were made on the surface course. The planning engineers had reduced by half the permitted deviation of the granular material from the ideal aggregate grading curve, compared with the tolerances allowed under German regulations. What's more, aggregate with high resistance to polishing was used for the surface course. This mix guarantees a road surface with uniform texture depth and perfect tyre grip. All aggregate for the asphalt package was hauled to the mixing plants from specially selected quarries, some of which several hundred kilometres away. The binder, too, was modified in line with the climatic conditions prevailing in northern India to ensure an outstanding mechanical and temperature stability at all times. Overall, the planning engineers' various measures allowed to achieve an extremely uniform pavement structure whose properties will endure for many years, despite changing climatic conditions.

Top quality assured by sample mixes and test areasQuality was the most important aspect, particularly when it came to paving the asphalt for the race track. For this reason, numerous sample mixes were prepared and laid on test areas before the paving work began. The formula, mixing plant parameters and materials were perfectly matched by the team of German and Indian operators and laboratory technicians. Access roads and tangents covering several thousand square metres were built in this way.

"Such sample mixes are essential for optimizing the quality of the asphalt surface course. All the various constituent parts of the asphalt, the mixing plant parameters and precision adjustment of the pavers can only be perfectly matched with one another on the basis of such tests," explains asphalt specialist Dr Rainer Hart. He developed the concept for the race track asphalt and supervised the asphalt work from selection of the aggregate in the quarry to paving and compaction.

Lower compression stress, better tire grip
On a racing circuit, the base and binder courses are very much thinner than on normal roads. This is due to the lower pressure acting on the asphalt package. Non-skid properties and evenness are far more important here. That is why the paving teams paid more and more attention to the pavement’s evenness as they worked their way up to the top of the asphalt package.

Cariphalte polymer-modified bitumen (PMBs) that was used in the asphalt mixtures for F1 & Moto GP racetracks - Shell Cariphalte Racetrack is a high performance modified bitumen

Asphalt paving for FIA Category 2 circuit (F1 tracks are Cat. 1) - The surfacing of Hampton Downs racetrack

Here are some links about asphalt paving done on NASCAR racetracks

Basic info of materials used for asphalt mix - Asphalt for race tracks

PPT presentation of complete process of paving a NASCAR Speedway from New Jersey Asphalt Paving Conference

Racetrack paveing for the Kansas Speedway

High Performance PMA Applications for Extreme Stress

[delacf]

Yesterday, the track was really shiny because of bituminous bleed. We have noted slippery track at Austin, of course. Cheers

[Cam]

Would any of you educated members know if there is a similarity between the low grip surface at Austin and a wet track in general? Reason for the question, I'm curious to see if there's a correlation between wet track performance and slippery track performance.

[aussiegman]

Would any of you educated members know if there is a similarity between the low grip surface at Austin and a wet track in general? Reason for the question, I'm curious to see if there's a correlation between wet track performance and slippery track performance.

What sort of comparison are you looking for??

[Cam]

After watching the Ferrari struggle on a 'slipper' track, I wondered why, as a wet track is also slippery, so the core strengths of a car that makes it go quick in the wet, should have worked at Austin too... but this area is why outside my scope and I have no idea, so thought I'd see if anyone knows or can give a reason as to why the two tracks don't really act the same.

[bhall]

I didn't think the Ferrari was that bad in Austin. Massa was quietly fast all day, and Alonso wasn't really in a position where he needed to push. (There's not much to do when the two cars ahead are 30 seconds ahead.)

In any case, teams use very different setups for wet races (higher ride height, softer suspension, higher AoA on wings, etc.), not to mention very different engine maps (less aggressive throttle combined with gentler gear shifts) when on wet-weather tires. Since there wasn't so much as a hint of rain this weekend, there was no reason for Ferrari, or any other team, to bias setup toward wet weather, and it's only under those (limited) circumstances that the F2012's (alleged) wet-weather prowess would be put on display.

[ubrben]

After watching the Ferrari struggle on a 'slipper' track, I wondered why, as a wet track is also slippery, so the core strengths of a car that makes it go quick in the wet, should have worked at Austin too... but this area is why outside my scope and I have no idea, so thought I'd see if anyone knows or can give a reason as to why the two tracks don't really act the same.

I'd question if Ferrari struggled? Massa had his best race for a while and Alonso was third. Vettel and Hamilton were different class in the two best cars. Lotus really struggled compared to Abu Dahbi and Ferrari were better relative to them in Austin.

No we've got that out the way, here's a good article with some images of the Austin track: http://circuitoftheamericas.com/article ... e-americas

It shows the most common type of new asphalt on racetracks. Mugello and Valencia in Europe have been resurfaced with this, and it's similar to most new tracks.

It's quite smooth in terms of macro-roughness and what I've seen with these surfaces is two main possibilities; high micro-roughness leading to decent grip, but heavy abrasion - Valencia was like this for the MotoGP. Crucially Valencia was used a lot more than Austin was prior to a big international series going there and they seem to have avoided the other issue, which is oil coming up and contaminating the track surface.

In some ways that contamination is similar to a water film in the sense that it lowers the frequency content of the surface and reduces adhesion.

Ben

[Jersey Tom]

Crucially Valencia was used a lot more than Austin was prior to a big international series going there and they seem to have avoided the other issue, which is oil coming up and contaminating the track surface.

This.

As for slick dry track vs. wet track... I think they're two entirely different things. If team 'X' is quite good in the wet it's part car control, but also part setup.

I think with the higher speeds in dry conditions it also emphasizes any downforce difference between teams as well. Little downforce goes a long way in masking handling issues.