The new 2,616-ft.-long Oakley C. Collins Memorial Bridge is comprised of a 900-ft. cable-stayed main span and two 370-ft. cable-stayed side spans, two 326-ft. tall towers and two anchor piers on the river’s edge. The structure is cast-in-place with 22,500 cy of reinforced concrete (5.8 million lbs. of rebar), utilizing the cable stays to construct the bridge by the one-directional cantilever method. Foundation units consist of 22 large, 96-inch diameter drilled shafts.

The 900-ft. main span is the longest span ODOT has ever built. Construction began in March 2012 and was completed November 2016.

There were several key modifications to the means and methods and design optimizations, most notably:

• Alternative construction sequence.
• Casting of the back spans in place using specially designed falsework.
• Land access to build the main span area.
• Precast concrete girders for floor beams on side spans.
• Precast stay anchor blocks.

Minimizing Water-Based Work – During the pre-bid phase, the Team wanted to minimize water-based work since this adds substantially to cost, schedule and safety risk, especially since the river can rise over 20 ft. in this area.

Constructing the back spans on falsework simplified construction, reduced construction time, increased project safety, and reduced the amount and size of equipment required for the cable-stayed portion of the project. The falsework was designed as a modular system, allowing it to be used for both the Kentucky and Ohio approaches and reducing the number of travelers from two to one. This, along with precast concrete girders for floor beams on side spans, allowed the Contractor to have land access to build the main span area.

These modifications to the construction sequencing saved costs and time, as well as providing a much safer work environment. Project officials concur that minimizing water work was a wonderful success. With an average of 50 workers on-site, on a daily basis, there was no lost time incidents on this project.

Precast Where Possible – The Team evaluated and identified elements that could be precast rather than poured in place, allowing items to be pre-manufactured under controlled conditions, while other work was able to continue. The use of precast cofferdams greatly reduced the amount of tremie concrete required, as well as provided a sacrificial form for the tower footing.

Precast tubs were used for footings at Pier 3 and Pier 4, eliminating the need for pile coffer cells, effecting schedule and cost savings. The precast tubs were tied into the drilled shafts, reducing its footprint, minimizing excavation and its impact on the environment, footing form costs and schedule time. In addition, floor beams were precast and stay-in-place deck forms were used on the side spans.

Precast Stay Anchor Block System – The design of an innovative precast stay anchor block system simplified stay cable anchorage placement, accelerated the construction schedule and simplified the form traveler system by eliminating the need for a temporary stay anchorage.