A Whole Different Animal

Feb. 12, 2007

Driving a racing car around a hairpin turn is difficult enough, but trying to drive a fully loaded asphalt truck or pickup machine around a hairpin turn is nearly impossible.

The asphalt trucks were on Infineon Raceway to lay a windrow of hot-mix asphalt (HMA). A pickup machine scooped up the HMA from the windrow and deposited it in the hopper of a paving machine as it was laying a new surface on Infineon Raceway in Sonoma, Calif., in 2003.

Driving a racing car around a hairpin turn is difficult enough, but trying to drive a fully loaded asphalt truck or pickup machine around a hairpin turn is nearly impossible.

The asphalt trucks were on Infineon Raceway to lay a windrow of hot-mix asphalt (HMA). A pickup machine scooped up the HMA from the windrow and deposited it in the hopper of a paving machine as it was laying a new surface on Infineon Raceway in Sonoma, Calif., in 2003.

“The 180° turn in turn 11, that was challenging to get the pickup machine, which is about as mobile as Hoover Dam, to keep a nice constant radius and get the trucks in and out of there on that real sharp turn,” Jere Starks, vice president of facilities at Infineon Raceway, told Roads & Bridges. “That was a bit of a challenge. But it all worked out.”

The preparation for paving started on July 27, 2003, with sealing cracks and cutting trenches for draining water under the track. The concrete curbs in the corners also had to be removed. The curbs are intended to keep the cars from cutting the corners too short, but the cars often drive over them anyway trying to shorten the path around the course.

Infineon Raceway is somewhat unusual for the NASCAR circuit because it is a road course rather than some variation on an oval. Infineon is a winding snake of a course that forces drivers to make right turns as well as the usual NASCAR-oval left-hand turns, go up and down hills and use their brakes much more than usual. They have to slow down to get around turns that have little or no banking, unlike the high-banked turns of a speedway oval.

The Infineon Raceway complex, including the 12-turn, 2.52-mile road course and a quarter-mile drag strip, was carved into the picturesque hills of Sonoma 30 minutes north of the Golden Gate Bridge in 1968. Its elevation at its lowest point is only 13 ft above sea level and at its highest point is 170 ft. The first race at the site was a Sports Car Club of America event held on Dec. 1, 1968.

Infineon is an extremely busy place, with events scheduled 340 days a year. The complex, owned by Speedway Motorsports Inc., plays host to the NASCAR Nextel Cup, the National Hot Rod Association drag racing, the American Motorcycle Association Superbike tour and the IRL IndyCar Series.

The NASCAR track qualifying record was set by Jeff Gordon on June 24, 2005, with a lap time of 1 minute 15.950 seconds (94.325 mph). The fastest NASCAR race winner was Ricky Rudd on June 23, 2002, with an average speed of 81.007 mph.

NASCAR’s debut at Infineon was a 1989 race won by Rudd.

Slow-speed chase

The paving vehicles working to place a new asphalt overlay on most sections of the road course were in a race of a different—and much slower—kind. They ran in echelon formation: one ahead and to the side of the other, but their paths overlapped enough to prevent forming a longitudinal seam that might not be adequately compacted and might, in the future, ravel and ruin the track.

The paving work was performed by Ghilotti Construction Co., a contractor that has worked with Starks in the past. It was a race because the next auto event on the track was scheduled for the day after the paving was finished.

“That was a real critical schedule, because we had cars on there the next day,” which was Aug. 23, Starks said. “Our track is used 340 days of the year. It’s very difficult for us to get to the track.”

The compaction target was 96% of optimum for the temperature and consistency of the material. The actual compaction achieved was verified by the HMA supplier for their own benefit and by an independent laboratory on behalf of Infineon Raceway.

The compaction started right at the paving machine with a dual-tamper-bar screed. Then a collection of steel-drum rollers and a rubber-tire roller got to work. Stokes recalled that the pavers and compactors were Caterpillar machines, and the pickup machines were made by Cedarapids (now Terex Roadbuilding).

Special recipe

The HMA used to overlay Infineon was a special blend created by Kimbel Stokes, a pavement consultant for Speedway Pavement Inc.

Stokes said he was the first one to start putting polymer-modified HMA on racetracks. It started in the early 1990s with a problem in paving the Charlotte Motor Speedway.

“We found that the track temperature at Charlotte Motor Speedway was getting up to 160°F on the track surface,” Stokes told Roads & Bridges, “and the liquid asphalt was actually melting and flowing down the turn.”

Stokes and top managers from Charlotte Motor Speedway and Speedway Motorsports, which owned the track, went to Southern States Asphalt in Nashville, Tenn. There, they tinkered with polymer modifiers and liquid asphalts until they found one with a softening point of 180°F using the ring-and-ball test.

They went back to Charlotte to pave the track with the new mix. This time it worked well, and that surface lasted 12-13 years and was just resurfaced this past spring.

Since the early 1990s, Stokes has used his HMA to pave many racetracks, including most of the tracks owned by Speedway Motorsports.

Stokes declined to give details of his proprietary mix, but he did say it contained a polymer-modified liquid asphalt and a maximum aggregate size of 12.5 mm. The liquid asphalt was supplied by Valero Energy Corp., San Antonio. The aggregate supplier and HMA plant owner was Syrar Industries.

The overlay placed on Infineon was 1.5-2 in. thick.

Best-laid plans

In some ways, paving a road course is more demanding than paving an oval; in other ways, it is easier. For example, a road course does not have the steep banking that a speedway oval has.

“I usually pave on the high-banked turns,” said Stokes, “but Infineon was a different animal altogether. You don’t have to have the specialized equipment with a road course.”

\ Because the HMA has a high softening point, it had to leave the plant, which is about 20 miles from Infineon Raceway, at about 340°F. At the plant, it was loaded into insulated trucks and covered with a tarp. Stokes checked the temperature of the mix at the plant and as it went down behind the paver.

“Typically it will hold its temperature for an hour or so,” he said. “That’s not a big issue.”

Smoothness is critical in racetrack paving, and to get smoothness paving machines have to be supplied with a continuous feed of HMA and move at a steady speed on their path. Infineon is located in a rural area and served by rural roads, which can be completely blocked by a single traffic mishap. Starks set up backup plans for every contingency he could think of, but often what strikes is unthinkable.

“I thought I covered every aspect of that. We had two different ways to get to the track. If there was a traffic jam on one way, we could use the other. We had ways of communicating. The only thing I didn’t think about, or we didn’t think about as a group, was what happens if the local utility company loses power to the plant.” That is exactly what happened. “That caused us some anxious time, but we were able to keep the material out in front of the paver.”

On sturdy shoulders

The base around the Infineon course was solid enough to support an overlay without having to dig deeper and reconstruct more of the racetrack. The base was even strong enough to support the paving vehicles. “The heaviest loads imposed on the racetrack are the actual construction itself,” said Starks. “Other than that it’s a totally different wear phenomenon. It’s shear.”

Instead of pounding up and down on the pavement the way heavy vehicles do on a highway, the very light racing cars on a racetrack push the surface of the pavement in a shearing motion. But heavy paving vehicles actually do pound up and down on the racing surface and subsurface, making paving a more delicate operation on a racetrack.

When Ghilotti turned out to be the lowest bidder, Starks was glad: “They understood how our facility works. They understood this concept that it’s different than paving an interstate.”

One problem with the racetrack and its base was that water would occasionally seep up through the pavement and make it impossible to race.

“We’re on the side of a hill,” Starks said, “and we have a terrible problem with water coming up through the ground. After a rain or winter, we would get several days of bleeding up through various areas of the track. We’ve lost a couple of national motorcycle races as a result of it. They wouldn’t run because there was water weeping through the track.”

For the resurfacing job, Infineon found the places where trench drains would do the most good and then sawed a trench across the track with a rock saw, put perforated pipe in, put drain rock in and then paved over the top of it. They did that going up the hill between the start/finish line and turn 2 and through turn 7.

“Over the years, we finally got the track to dry out,” said Starks.

Starks thinks the surface will last 10-12 years, depending on weather and other circumstances.

Infineon Raceway is proud that it repaved the track and got very good reviews afterward.

About The Author: Allen Zeyher is the Managing Editor of Roads & Bridges. He can be reached at [email protected]

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