The 5th Street Pedestrian Plaza Bridge project provided an enhanced pedestrian corridor linking the Georgia Tech campus on the west side of the I-75/I-85 Downtown Connector to the new campus expansion on the east side of the connector. This was the first GDOT design-build project in the Atlanta metropolitan area and we served as the prime contractor for construction. The new structure was designed with a green space of lawn and planter areas, stepping up from behind 25 ft wide sidewalks. This provided a broad, open area that eliminated the feeling that the campus was severed by the 15 lanes of interstate traffic below.
The new 5th Street bridge has three traffic lanes plus two bike lanes as well as a 25 ft wide sidewalk on each side of the roadway. On the back side of the sidewalk, a continuous concrete bench creates a pedestrian friendly border that transitions into a spacious pedestrian accessible lawn area, bordered by terraced planter beds. The lawn areas have 18 in. of soil on the bridge deck and the deepest planter beds contain 6 ft of engineered backfill material to minimize the load on the bridge deck. The planter areas are landscaped to provide a park like setting. All landscaped areas include an irrigation system with a complete underdrain system on the bridge deck.
The new structure was constructed 11 ft longer to the east and 16 ft longer to the west to accommodate future widening needs on the downtown connector below. Site constraints in this urban environment created a need for real creativity when developing the plan for both demolition and construction of the new east abutment wall. Hayward Baker Inc. was engaged to be our partner for this component of the work. We combined the use of caissons, micro piles and battered tension micro piles to design a unique abutment wall system for use in the very tight confines of the east end of the site.
One of the most significant challenges on this project was maintaining a continuous flow of traffic on both the 5th Street bridge and on the downtown connector below during construction. This required implementing a staged-construction scheme for the new structure. The new widened part of the structure was built first and then 5th Street traffic was temporarily rerouted onto it while the remainder of the new bridge was built.