|
Exacting specifications are the order of the day
on test track project
By Diane M. Calabrese
For automotive companies, the most important tests come well before a vehicle ever travels on a public roadway. Trials allow for research and development, as well as safety fine-tuning.
 |
| The ride quality on this pavement is 3 inches per mile, resulting in a very smooth surface. |
On July 27, 2005, TRW Automotive Holdings Corp., one of the world’s top 10 automotive suppliers, announced that its Kelsey-Hayes Co. subsidiary had won approval from the Locke Township Planning Commission to build a center to develop active safety systems for TRW braking, steering, and suspension products. The Locke Township facility, which is situated on 262 acres near Lansing, Michigan, is just 10 miles from the TRW manufacturing plant in Fowlerville, Michigan.
Being able to ask “what if” in any experiment hinges on controlling variables. At the TRW test track in Locke Township, the ability to control variables begins with a pavement designed and engineered to exacting specifications.
The test-track project reached 60 percent completion in early September, says Leonard C. Becker, PE, Project Manager for Wilcox Design-Build, Cadillac, Michigan. “The earthwork began in July,” he says. “We are ready to place the asphalt.”
Wilcox Design-Build is the construction manager for TRW. The firm has had responsibility for everything from site selection to concept layout and final design, as well as special land-use permitting and all permits and applications. Ajax Paving Industries, Inc., is the asphalt contractor and expects to be on site through November 2006.
Elements
The “skid traction” facility is soon to be completed in Locke Township, according to Wilcox Design-Build, with other components to be added later. “It has two pads, a high-friction pad and a low-friction pad.”
The high-friction aspect is made of high μ (coefficient of friction) asphalt, and it has an average slide friction coefficient of 0.90. “The high-friction pad is used to complete dynamic vehicle testing,” says Becker. “The low-friction pad is used to complete split μ testing.”
The low-friction pad consists of four different sections: ceramic tile, concrete (dry), Jennite-coated asphalt, and wet asphalt. In addition, the ceramic tile and Jennite-coated asphalt sections of the test track are fitted with sprinkler systems. The sprinklers allow surfaces to be wetted, replicating ice and
snow conditions.
The low-friction track is structured so that professional drivers can gauge their braking points to put tires on two different surfaces and then brake. That enables the research team to analyze what happens when brakes are applied and tires meet different levels of resistance.
All-weather testing will be done at the facility but only under simulated conditions. To protect the integrity of the test surfaces, snow is not plowed away; it must melt.
Uniformity
“One of the most fascinating parts of the project is the tight tolerances for asphalt smoothness and friction,” says Becker. “The ride quality on this pavement is 3 inches per mile.”
That is exceedingly high uniformity with very few blemishes. The physics of linking road quality and ride roughness begins with a consideration of how many vertical inches of displacement a vehicle is subjected to while traversing a mile of pavement. In short, “3 inches per mile” results in a very smooth surface. The pavement needs to be this smooth so there is nothing to trigger a vibration.
Leveling the pavement to conform to the precise needs of TRW for testing is a must, says David Marshall, Project Manager with Ajax. The material transfer device used is a familiar one from state highway projects, he explains, so everyone is accustomed to the methods.
It takes special effort to meet the project’s exceptional standard of uniformity, and it must all be done while maneuvering without incident across longitudinal joint heaters between adjacent lanes.
Asphalt
Ajax is using 13A and 36A asphalt for the paving component in its contract. These types of materials were specified by the track owner because of the quality the finished surface exhibits.
Getting everything right begins with the way the stone is prepared. “Our contract is to fine grade stone and place asphalt,” says Clarence Jones, Estimating Manager with Ajax. “The tolerances on the stone are tight. You have to make sure you don’t place the stone too low,” which would increase the thickness of the asphalt.
Any additional asphalt required would be a cost Ajax would have to bear, says Jones. Adhering to the amount set by the specifications for the project is a commitment Ajax takes seriously.
Asphalt surfacing, which will total 55,000 square yards, is on schedule for completion by November. Marshall says he naturally frets a bit about weather as winter nears, but everything is going well.
Becker, Marshall, and Jones bring abundant expertise to the project from prior work on test tracks. Jones and Marshall, for instance, have worked on test tracks for General Motors, Ford, and Bosch.
All-weather testing will be done at the facility
but only under simulated conditions. To protect the integrity of the test surfaces, snow is not plowed away; it must melt.
The Future
Keeping things moving, even before the test drivers get going, was a high priority. “It’s going from a farm field to a test track in six or seven months,” says Becker. “It’s being done in a compressed construction schedule.”
But the test track is just the beginning. “It’s the first in a multiphase development that TRW is undertaking in Locke Township,” says Becker.
The TRW Automotive Vehicle Development Center is expected to eventually employ more than a dozen full-time engineers and track technicians. The track constructed will support 24 vehicles in staged testing. Down the road, there may be a fleet as large as 200 vehicles.
Later phases will include a vehicle-dynamics area, traction-control grades, and a high-banked oval, according to TRW. All phases are being constructed to minimize noise and environmental impact on the surrounding community. |
