Orlando Paving Co. (OPC), a division of Hubbard Construction Co., is accustomed to the varying project demands crews face on a daily basis and a recent visit to two current projects proved just how diverse those projects can be.
As a subcontractor on the State Route 429, the Western Beltway that interconnects the Greater Orlando area, OPC is in the final stages of its asphalt work, which involved placing 82,000 tons of hot mix asphalt. Granite Construction Inc. was awarded the $45.6 million toll road project owned by the Florida Department of Transportation in early 2004.
The project is a continuation of SR 429, a limited access toll road in Orange and Osceola counties west of Orlando. The project included the construction of 5.7 miles of a new four-lane divided asphalt paved roadway, seven bridges, and all associated frontage roads and on/off ramps. There were three box culverts that needed to be built, an extensive drainage system, signing, lighting and a signal system. The project required the on-site excavation of one million cubic yards and the import of two million cubic yards of fill materials. Work began on the project in May 2004 and is expected to be completed by early 2006.
The center of the project intersects with the Western Connector Road, a Granite project built for The Reedy Creek Improvement District. Granite completed four other projects on SR 429.
According to Paul Miller, OPC's project manager, the $5 million asphalt portion of the project covered placing 4 inches of structural 15- to 20-percent recycled Superpave HMA course containing a 5.5 percent PG 67-22 binder over a lime rock base, followed by a ¾-inch open graded friction course containing a 12-percent ground rubber additive in the PG 67-22 binder.
"We started our work in September 2004, and we'll complete paving by the end of April," Miller says.
On another project, the rehabilitation of taxiways E and F, along with the associated taxiway connectors at Orlando International Airport, OPC received the general contract bid of $14.5 million to widen the existing taxiway structure to accommodate future flights of the new jumbo Airbus A380 jetliner. The existing 75-foot-wide taxiways had to be expanded by 18.5 feet on each side to provide a hard surface underneath the engines of the A380.
"On this project we had to trench out the adjacent shoulders and then mill 2 inches off the existing taxiways and taxiway connectors, and then put back 5 inches of new asphalt," says Robert Tanksley Jr., field engineer. "We'll be able to use the millings to build up a 6-inch compacted subase under the granular (lime rock) base on the expanded width of the taxiways and taxiway connectors, and when we're completed later this year we expect to place 70,000 tons of new asphalt."
Robert E. Boyer, PhD P.E., a consultant for OIA and past district engineer of the Asphalt Institute, designed the pavement section for the project.
"It's a Superpave design that had to meet a gyratory specification of 100 gyrations," Boyer says. "We were working with mix designs containing a PG 76-22 binder, as well as designs containing a PG 64-22 rubber additive binder."
Because of the existing marshy ground water conditions, the project called for an armi (asphalt rubber membrane interlayer) layer to be placed over the milled surface, as well as the expanded taxiway areas, prior to placement of the new HMA mats to prevent any water from percolating up through the new pavement.
"The Superpave design specification is patterned after the Federal Aviation Administration's EB 59 design used for taxiways and runways," Boyer notes. "It's a design that can be used anywhere in the country. What was unique about this project was the requirement to place a rubberized membrane in between the milled surface and the new HMA to prevent any moisture damage to the new mat."