Preserving Arlington Memorial Bridge

Paving Crew Acutely Aware of Angles at Darlington Raceway

Fri August 03, 2007 - Southeast Edition
Jodi Helmer



There are no racecars on the track but there is still a lot of fast-paced action at Darlington Raceway. A $10 million construction project that includes building a new access tunnel and repaving the track is moving full speed ahead this summer.

“Darlington is unlike all of the other tracks we’ve worked on,” explained Jason Burns, project engineer at Sunmount Corporation, the Texas-based firm overseeing the construction project. “The track’s slogan is ’Too Tough to Tame’ and this project is a good example of how it got its name.”

“Most tracks are symmetrical but Darlington is not. The radius of the turns is different at both ends; turns one and two have a wider radius than turns three and four,” Burns added. “The banking is also different; there is 25 degree banking at turns one and two and 23 degree banking at turns three and four. There is nothing normal about this track.”

The track was built in 1950 with two access tunnels — the first at turn one and the second at turn four. The existing access tunnels measure just 8 ft. (2.44 m) tall, making it impossible for car haulers or emergency vehicles to reach the track.

“Right now, if an ambulance or fire truck needs to get on the track, the race has to be stopped,” Burns said. “If a car gets in a wreck, it’s stuck there until the race is over.”

A new access tunnel that measures 226 ft. (68.9 m) long, 32 ft. (9.75 m) wide and at its tallest point is 18.5 ft. (5.64 m) tall is being built at turn three.

Rea Contracting, a construction firm in Charlotte, N.C., is the subcontractor in charge of excavation. A John Deere 450 is being used for excavation and a Volvo 330 ton truck will haul debris off-site.

The site will be excavated down 12 ft. (3.66 m) where crews are expected to hit groundwater. At this point, vacuum pumps will be brought in to draw out the water, 12 in. (30.5 cm) of stone will be spread and new sheeting will be installed before the slab is poured.

Construction of the access tunnel also includes erecting 7.5 ft. (2.3 m) wing walls on both ends of the tunnel and setting a pre-cast arch for the tunnel.

The second phase of the project is repaving the track. The existing track has not been paved since 1995 and ruts and cracks had worn into its surface. Driving conditions could become quite treacherous for racers if the track is not repaved.

Workers will mill off 3 in. (7.6 cm) of the track, replacing it with new asphalt to guarantee a much slicker surface when drivers hit the track next season.

It will take a total of 17,000 tons (15,400 t) of asphalt to repave the track. A Wirtgen Mill 2000 with a 3-in. (7.6 cm) roller will be used to pave the front and back stretches of the track and a Wirtgen Mill 1200 will be used to pave the turns.

“The 1200 is a smaller machine with a lower center of gravity making it less likely to flip over on the banked parts of the track,” Burns said. “A brace will be attached to the machine for extra assurance that it will stay upright.”

Sunmount Corporation has built an on-site plant at Darlington Raceway to allow for complete control of the material used during the paving process.

“The paving material needs to be tightly controlled when you’re paving a racetrack because the specifications are very stringent,” Burns said. “Having a plant on-site means that we’re not worried about dealing with a supplier.

“There needs to be continuous forward movement when we’re paving,” he added. “We couldn’t take the risk of needing more material and having the supplier tell us we’ll have to wait two weeks.”

Two tri-axle dump trucks will be parked outside of turn three and during the initial paving work the trucks will have to drive through the gate and over the track to deliver material. The new access tunnel will be completed at the same time the surface paving is set to begin and at that time, the trucks will use the new tunnel instead of driving over the partially-finished track surface.

On the main track, a Bomag 84-in. (213 cm) double drum roller will be attached to a Komatsu K61EX dozer to pave the front and back stretches.

The banks are too steep for the material transfer vehicle, a Roadtec 1500, to be used on the track. Instead, the truck will sit on the flat part of the track and material will be fed from the truck to the roller using a conveyor. The conveyor is built in sections that extend to various lengths depending on where the paving is being done.

A 60-ton (54 t) Link-Belt crane with an auger in the bottom will feed the asphalt from the truck to the ABG Titan 525 paver that is on the banked turns.

“The ABG Titan 525 is a monster of a machine,” Burns said. “You would not want to see a paver of that size going down the highway; highway pavers are about half the size but a large paver allows for greater compaction of the asphalt on the racetrack.”

Construction began in mid-July and is expected to last until the end of November. A crew of 20 is working on the access tunnel and a second crew of 20 is working on the paving project.

Once construction is complete, Darlington Raceway will open the track to several driving schools that will help break in the new surface before racing season begins in May. In the meantime, a new billboard outside the racetrack reads, “New Asphalt, Same Attitude” — a pronouncement that will have fans clamoring for tickets to see races at Darlington Raceway next season. CEG