Project Overview
The Arlington Memorial Bridge is not just another transportation route for locals and tourists. It is an iconic element of the entrance to the nation’s capital. The neoclassical bridge spans the Potomac River, linking the Lincoln Memorial in the District of Columbia to the Arlington National Cemetery in northern Virginia and serving an estimated 68,000 vehicles daily.
After nearly nine decades of dedicated service, the bridge needed a major rehabilitation to extend its service life. In 2017, the National Park Service (NPS), in coordination with the Federal Highway Administration (FHWA), solicited proposals for the rehabilitation project through a two-phase, design-build process. The project was awarded to Kiewit Infrastructure Company in partnership with AECOM.
The goal of the project was to restore the bridge’s structural integrity while protecting and preserving its memorial character and significant design elements. The designers used precast concrete bridge elements in the design to help meet all of the project goals.
“The use of precast concrete deck panels was a requirement and essential to the success of this project,” says Stephen Matty, project manager in the bridge design group for AECOM. The use of precast concrete deck panels facilitated rapid construction while minimizing disruptions to the traveling public, and it provided a cost-effective approach to achieving the durability and service life requirements in the contract.
In addition, the use of ultra-high-performance concrete (UHPC) closure joints with a minimum 28-day compressive strength of 21,000 psi minimized the number of expansion joints required for the project.
High performance, lower cost
The project involved the rehabilitation of the concrete arch approach spans, including replacement of the existing cast-in-place reinforced concrete deck, and design and construction of the replacement of the moveable bascule span with a fixed steel girder span.
For the first phases of the project, designers used 450 precast concrete deck panels and replaced all of the internal concrete beams and columns on top of the piers. The later phase included replacement of the existing cast-in-place deck with precast concrete deck panels and link slabs to minimize open joints. Ten reinforced concrete arch approach spans and a multigirder steel center span were placed over the navigable channel, with eight arches spanning directly over the Potomac River.
The precast concrete deck panels were about 10 ft long and 42 to 44 ft wide, and were connected at each cross wall using 5-in.-wide UHPC closure joints. The 82 precast concrete beams were about 44 ft long and 2.5 ft deep. Each precast concrete beam was connected together along the center of the bridge using 8-in.-wide UHPC closure joints to form a continuous transverse floor beam.
High-performance concrete (HPC) was used in the sidewalks, approach slabs, cross walls, beams, caps, columns, and precast concrete deck panels, with 28-day compressive strengths ranging from 4500 to 6000 psi.
“The precast concrete deck panels with HPC, UHPC closures, and stainless steel reinforcement provide a level of protection to the supporting structure that will extend the life of the bridge for another 75 years,” Matty says. “The partnership between the FHWA and NPS was key to the success of this project,” adds George Choubah, FHWA lead structural engineer. “Everyone on the team worked very hard to make sure that the fast-paced design and construction schedules were met without jeopardizing the quality of the final product,” he notes. |