ConRAC Bus Platform and Bridge Ramps
Consolidating the rental-car, bus and taxi services at Logan International Airport in Boston required constructing a 1.2-million square-foot parking facility with open interiors to provide flexibility for the seven rental-car facilities using it. A bus-platform bridge connecting this structure to bus drop-offs and spanning a busy roadway also was created using precast concrete Northeast Extreme Tee (NEXT) girders.
The new Consolidated Rental Car Facility (CONRAC) handles approximately 5,000 vehicles on four-levels, plus a 111,000-square foot Customer Service Center building, and Quick Turnaround Areas for maintenance and storage for rental-car operations. The facility consolidates operations and cuts shuttle-bus traffic from 99 buses to 28, allowing more flexibility and faster routes. It also allowed the buses to gain access to the upper (Arrival) levels of the CONRAC structure, requiring the bus platform.
The NEXT Beams used for the bus platform are bridge double-tees with 13-inch-wide tee legs that are beefier but stouter than those used in parking structures. This shape produces greater strength and shallower depths. The designers included the NEXT Beam as a design alternative, following recent approval of the shape by the Massachusetts Department of Transportation.
“It turned out to be the right way to build it,” says Camille Bechara, Project Manager and lead designer with Parsons Brinckeroff, the architectural and engineering firm on the project. “The NEXT Beams were lighter and quicker to erect than alternatives, all of which also were significantly more expensive to build.”
The 600-foot-long bridge features four NEXT Beams per line. The girder spans vary in length from 60 to 85 feet and are 3 feet deep. To ensure the bridge aligned with the structure’s floor, the ends of the last span of beams were dapped to even the height. “We could not have done that with box beams or other girder shapes,” he says. “The NEXT Beam’s light weight allowed them to be handled easily and erected quickly.”
Traffic diverted for approximately 10 hours at night to erect components
Traffic was diverted for approximately 10 hours one night to erect the pieces that spanned the road, while the other portions were set during the day. Two cranes were used, one of which also was used to erect portions of the parking structure.
The girders were transported from the precaster’s plant in Connecticut, requiring close planning due to the girders’ weight, which was up to 71 tons. All bridges between the plant and site were analyzed and a rating analysis evaluated to ensure they could handle these “super-loads.” Some requiring speeds of 5 mph or restricted traffic while the trucks passed over them. “It took a great deal of detail and precision planning, but it worked out very well,” Bechara says.
The bridge portion of the project has been completed and will begin operation when the parking facility is completed later in 2013.