Photos: Max Anton Birnkammer Photography

“This project showed an impressive use of precast concrete in a very tight geometric condition.”

Kevin Eisenbeis

 

Bridges: Main Span from 76-150 Feet

Terminal Roadway at Maynard H. Jackson Jr. International Terminal, Hartsfield-Jackson Atlanta International Airport

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Geometry, material quantities, and schedule restrictions posed key challenges for completing the new terminal roadway at Hartsfield–Jackson Atlanta International Airport on time and on budget. Those goals were achieved with a design for the 5285 ft (1611 m) structure that featured 578 AASHTO Type III precast concrete girders and 36 precast concrete box-beam girders.

The dual-level bridge includes 70 spans with tight vertical and horizontal curvatures along its length. It has 14 horizontal curves and 12 grade changes. It also supports two canopies, provides multiple access points for vehicles and pedestrians, and allows future expansion with minimal disruption to traffic.

The precaster needed to produce beams with beveled ends, often varying within a single span, to match the different bent skews required by the complicated geometry. The precaster also produced beams with multiple sleeves in various locations along the beams to handle demands for drainage as well as act as conduits for lighting, security, and communication systems.

“This project showed an impressive use of precast concrete in a very tight geometric condition,” says Kevin Eisenbeis, a member of the transportation awards jury.Using precast concrete to build this bridge allowed it to be constructed faster and at less cost than other alternatives.”

The speed of casting, delivering, and erecting the precast concrete girders allowed the contractor to meet an aggressive construction schedule. Multiple deck crews could work simultaneously because the girders could be erected on both bridge levels at a time. At its peak efficiency, crews erected 200 girders in one week.

A gantry system was used to erect girders on the bridge’s upper level, moving transversely on steel-beam rails mounted on the lower-level bridge deck. This system allowed the lower-level deck to be constructed with a single concrete pour.

Construction was also aided by an innovative design for the canopy’s column supports. The supports were placed 40 ft (12 m) on center, requiring a column at midspan that would produce large overturning moments to the superstructure. To accommodate this loading, four beams were tied together using a large concrete diaphragm. This allowed them to resist the overturning moment by acting as a couple with two beams on each side of the columns.

“This project demonstrated precast concrete can be used in structures with complex geometry,” says Myint Lwin, a member of the transportation awards jury. “It shows that in these types of projects, designers can think about using precast concrete elements to meet demands and be cost effective.”

Location: Atlanta, Ga.
Owner: City of Atlanta Department of Aviation, Atlanta, Ga.
Engineer: Atkins Global, Atlanta, Ga., www.atkinsglobal.com
Contractor: Holder Manhattan Moody Hunt, a joint venture, Atlanta, Ga.
Bridge contractor: Matthews/Thrasher, a joint venture, College Park, Ga.
Precaster: Gulf Coast Pre-Stress Partners Ltd., Jonesboro, Ga., www.gcprestress.com
Precast girder erector: Thrasher Contracting, Atlanta, Ga.
Bridge length: 5285 ft (1611 m)
Project cost: $35.1 million