Repaving is the last possible remedy a track wants to use, but when potholes (see: Daytona) show up, there is no choice but to tear up the old asphalt and replace it with new, fresh blacktop. In the last few years, Daytona, Phoenix, Michigan, Pocono and Kansas have all been repaved.
We hear a lot from race teams about their ‘notebooks’ – the collected wisdom and experience from prior experiences at a track. When that track is repaved — or reconfigured — the notebook pretty much goes out the window . They have to start over.
They’re not the only ones. I had a chance to talk with Greg Stucker, Manager of Race Tire Sales for Goodyear as part of an article I was working on for a British publication called Race Cup Technology about the many challenges inherent to ensuring that the tires provided to the teams are safe and fast.
Goodyear doesn’t categorize tracks the way most of us do, with the superspeedways, mile-and-a-halfs, short tracks and road courses. They have to take into account not only length, but the track surface and the loads the tires experience.
|Group 1||Daytona, Talladega|
|Group 2||Charlotte, Chicago, Darlington, Homestead, Kansas, Las Vegas, Michigan, Texas|
|Group 3||Atlanta, California, Dover, Kentucky|
|Group 4||Bristol, Indy, Iowa, Phoenix, Pocono|
|Group 5||New Hampshire, Richmond, Gateway|
|Group 7||Sonoma, Road America, Mid-Ohio, Ontario, Watkins Glen|
This results in seven “venue groupings”, with superspeedways and road courses in their own categories. Martinsville, that unique concrete corner/asphalt straightaway hybrid also stands in a class by itself. The remaining tracks are categorized into four groups.
Although Atlanta and Kansas have similar length and shape, they are in different groups. Atlanta’s surface is much older and rougher. Speeds are higher. That places different demands on the tire than a smooth, newly paved surface like Kansas. Goodyear’s categories change almost yearly as tracks age and are repaved. Kansas used to be in the same group as Atlanta prior to the former’s summer 2012 repave.
You wouldn’t think that Bristol, Iowa, Indy, Phoenix and Pocono had much in common, but as far as tires are concerned, they are all in the same group because of the combination of track surfaces and loads.
There’s another dimension to consider here: time. Michigan and Kansas - two tracks in the same venue grouping – were paved within six months of each other. Stucker points out that the surfaces aren’t aging the same way. This is a combination of on-track activity, and the vagaries of weather – how extreme the temperature changes have been, how much moisture the tracks have sustained, etc.
Goodyear is starting a new program to record representative three-dimensional images of track surfaces as a function of time so that they can develop a better understanding of how track surfaces age.
The track-mapping project uses a technique called fringe projection. Imagine that I create a pattern of alternating light and dark stripes, similar to the one in the upper right hand side of the graphic below.
I’m going to project that pattern onto a surface and use a camera to capture the reflection. A perfectly smooth, regular surface will not distort the pattern; however, if there are any irregularities – bumps or voids for example, then the stripe pattern will be distorted.
By varying the pattern and the angle at which the pattern is projected and recorded, you can use some very fancy mathematics to work backward and determine the shape of the surface that’s responsible for the distorted reflection.
The picture below shows you an example of a stripe pattern and the effect of shining the stripe pattern onto a toy fish.
Goodyear’s project will produce a series of 1.5 by 2-inch samples that can display details as small as three micrometers (about one ten-thousandth of an inch). This is smaller than the diameter of a red blood cell and about a tenth to a thirtieth the diameter of a human hair.
This surface-mapping project will help clarify both the smaller year-to-year changes of track surfaces due to weather and use, but also will provide information on how major changes like whole-track resurfacing or reconfigurations affects the racing.
Stucker points out that track technology constantly changes. You can’t compare the most recent repave of Daytona with the repave more than a decade ago. One big difference is that the binder – the black sticky stuff that sticks the rocks together – tends to be much denser than it used to be. The denser binder prevents water penetration and is more durable, which should decrease how frequently the tracks have to be resurfaced; however, that increased density means that it takes a lot longer for the track to start showing signs of wear.
It’s a cool application of a new technology that is being applied to a large number of possible uses. The “light” used for these measurements can be any type of light, including lasers, visible light and/or infrared or radio waves, depending on the particular data desired. This technology is used in Microsoft’s Kinect camera, which is used on the XBox to translate a user’s motions onto a computer display. That system uses infrared light. Other applications include 3D imaging of the mouth (for dental work), of vascular walls, for facial reconstruction, corrosion analysis and failure evaluation.