Project Overview
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 features precast concrete girders and 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.
This project demonstrated precast concrete can be used in structures with complex geometry. It shows that in these types of projects, designers can think about using precast concrete elements to meet demands and be cost effective.
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.
Precast Solution
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.
The precaster produced 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.
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. |