iROX Road Expansion Marks First Fla. DEF Project

Mon August 10, 2009 - Southeast Edition
CEG

The 9500’s long-reaching placing belt, more than 35 ft. (10.6 m) long, conveys the trimmed material into an awaiting dump truck.
The 9500’s long-reaching placing belt, more than 35 ft. (10.6 m) long, conveys the trimmed material into an awaiting dump truck.



The iROX Road Expansion Project is making history in southwest Florida. It’s the state’s first design/build/finance (DBF) project, creating new northbound and southbound lanes on the inside of the existing lanes on 30 mi. (48.3 km) of Interstate 75. The work will all be completed in just more than three years.

According to the iROX Web site, the project is extraordinary on many levels. First, its size: expanding 30 mi. of I-75 to six lanes. Second, the timing: it cuts five years off the timetable for a job this size. Third, its flexibility: work was begun on the project while engineers were still designing other segments.

LeeMar Building and Construction, with headquarters in Fort Myers, Fla., is part of a joint-venture team working on the first 17 mi. (27.4 km) of the project. They are a subcontractor to Anderson Columbia Company Inc.

Part of LeeMar’s responsibilities on the project is building the subgrade and base for the new lanes of interstate. It bid the project using scrapers and motorgraders. It wasn’t until after the company won the bid that its GOMACO distributor, Flagler Construction Equipment LLC, with offices in southern Florida, introduced LeeMar to the 9500 trimmer.

LeeMar knew it would want a machine that was capable of trimming a full 12 ft. (3.7 m) lane in a single pass. The trimmer would need to be powerful and rugged enough to cut through 2 to 3 in. (5.1 to 7.6 cm) of hard material. The finished grade also would have to be able to pass a strict inspection process after trimming was complete. And LeeMar wanted a distributor that could offer local support on the new machine.

“Dean Bengford with Flagler and Vinnie Miller from GOMACO came down and met with us and were an integral part of getting us involved with the 9500,” Butch Felts, vice president of LeeMar, said. “They gave us the comfort level to move ahead with this even though we had never used one of these machines before. We have a level of trust with Flagler. They confirmed this was the machine we had to have, so here we are.”

LeeMar’s 9500 is equipped with a 12-ft. mining head. It is using it to trim the stabilized subgrade surface and then the final lime rock base.

“Our subgrade material is a 40 LBR [load-bearing ratio] plus that’s a dirt and rock mix,” Felts explained. “It’s just a really sandy, rocky material that we’re trimming. Then, the lime rock that we use for our finished base course is a true limestone that we put down, compact and then trim. We’re taking from 3 inches down to 0.25 inches when we trim. We’re not spending a lot of time prepping the surface. We’re just getting in, compacting it, and letting the 9500 leave the finish. We’re paving right behind it.”

LeeMar is building the new roadway 24 ft. (7.3 m) wide, which requires two trimming passes. When trimming, LeeMar tries to average 1 mi. (1.6 km) a day production, including both lanes. That’s an average of 13,000 sq. yd. (10,869 sq m) in a six to seven hour time frame. The remaining two to three hours in the day allows the inspectors time to perform testing and give the go-ahead for paving on the grade the next day.

The grade’s inspection process is a rigorous one.

“We have density testing and verification from the state,” Felts said. “Then they use a straightedge and stringline to check the tolerances of our finish. They do cores to make sure our thickness is correct. Coring is kind of a double-check, because they’ve already stringlined the subgrade and the lime rock. Once that is done, the grade is sprayed with a prime coat and then the pavers can have it.”

LeeMar has its system worked out so it can get its day’s trimming accomplished and the inspection process completed in one day. The weather in southern Florida can be unpredictable, to say the least, with rainfall averaging more than 20 in. (50.8 cm) per month during the summer.

Working only 6 ft. (1.8 m) away from live traffic going 70 mi. (113 km) per hour also keeps Felts’ crew alert and aware of their surroundings at all times.

“Traffic is extremely busy and we actually have no barriers between us and the vehicles,” Felts said. “We’re trimming against the edge of the existing road and we have a 6-ft. wide area between us and the actual cars going by us. They have barrels every 100 ft. that just lets the cars know where they’re at.”

Building onto the existing interstate also created challenges. The line and level of the new lanes has to match with the existing lane. LeeMar equipped its 9500 with a rolling grade ski. On the first trimming pass, grade is taken off the existing lane. Then for the second pass, the first trimmed pass is used as a control. The steering sensor for the 9500 runs off the edge of the existing lane for both trimming passes.

“We’re using the standard steering sensor for steering and the rolling ski for elevation control,” Felts explained. “Our control is whatever is existing, which does change because it’s an existing highway. The rolling ski is working great for us.

“That first pass, too, we’re trimming right up to the edge of the existing roadway. We have a 15.5-inch drop-off from the roadway down to our subgrade so GOMACO custom-built a knife for us. The knife shaves that vertical edge perfectly and we don’t have to go back and clean it up.”

LeeMar’s 9500 is equipped with the GOMACO G21 digital control system. It also has the optional slope transition system and Super Slope software. The features help LeeMar with automatic and smooth corrections for grade elevation.

“We had the software added to handle our superelevation turns,” Felts said. “We have quite a few vertical curves and superelevations that are constantly switching, so we’re using that feature a lot. It’s really simple to do. You just enter everything into the G21, your start and stop point, the length of it, if you have to go from a plus 2 percent to a minus 2 percent, and the computer counts it all. A timing wheel measures out the distance and the controller automatically adjusts the cutterhead as the machine walks through and floats that superelevation in there. It’s really a great feature.

“When we first got this machine, we were scared to death and thought it was going to be like learning rocket science to be able to operate the thing. It truly did not turn out that way. Within three hours of getting our training on it, we were hot and ready to go.”

The company has two years to complete its portion of the work on the iROX expansion project. It estimates the work will be done in just more than a year. They’ll have trimmed 136 mi. (219 km) of base material by the time the project is completed.

“This project is getting inspected to death and our tolerances have been right on. The inspectors are very pleased,” Felts said. “For the guys paving the project, the grade is way beyond anything they’re used to receiving and their yields are no problem for them.

“The 9500 is amazing. We bid the job not even knowing about the GOMACO, and I would say we’re cutting our grade time in half because of it.”

This story was reprinted from GOMACO World, Vol. 36, No. 3.