I-95 / I-295 North Interchange – Jacksonville, Florida

The I-95/I-295 North Interchange project, located 1.5 miles south of the Jacksonville International Airport, is divided into three separate construction phases due to funding constraints. The purpose of this project is to improve capacity and operations by replacing the existing partial cloverleaf interchange with an all-directional four-level, system-to-system, high-speed interchange.

The first phase, completed in November 2010, included a new 2,256-foot-long, $16.3-million precast segmental concrete box girder flyover bridge that provides for the southbound I-95 to eastbound I-295 movement. The bridge consists of 10 spans and has a maximum span length of 274 feet and an overall width of 49 feet 3 inches. The bridge has a horizontal curvature of more than 90 degrees with a radius of 1,250 feet.

Innovation of Design and/or Construction

The I-95/I-295 flyover bridge complies with Florida Department of Transportation’s latest requirements for post-tensioning systems. One of the biggest changes to the industry was the introduction of the segment duct coupler used at the interface between precast segments for internal tendons. The segment duct coupler increases the protection to the prestressing strands leading to an overall improvement in durability of the bridge, providing a longer-lasting structure for maximum sustainability.

Aesthetics and/or Harmony with the Environment

A deciding factor for the superstructure was aesthetics. This extremely long flyover was going to be a third-level structure with its underside highly visible to drivers traveling on I-95 and I-295. Since the interchange acts as a north gateway for tourists and visitors traveling from the local airport into the City of Jacksonville, FDOT agreed with city officials to emphasize aesthetic elements of the bridge.

The resulting precast segmental concrete box girder is an elegant structure due to the closed box shape, clean lines and smooth bottom soffit. To further enhance the bridge aesthetics, octagonal columns were used and the capitals were flared at the top, matching the slope of the webs of the box girder. The tapered shape of the capital provides an elegant transition between the box girder and the supporting column. The columns measured 9 feet transversely and 7 feet longitudinally at their base.

Cost Competitiveness

Three types of superstructures were considered during the initial Bridge Development Report (BDR). However, only steel box girders and segmental concrete box girders were ultimately considered feasible. Each alternative was compared for aesthetics, constructability, maintenance costs, and construction cost, with consideration of the present value based on life-cycle analysis. The most influential parameter was construction cost. Construction professionals in Florida agree concrete superstructures are the most economical choice.

Typically precast concrete box girder bridges are considered economically efficient when there are over 500 segments. Since the I-95/I-295 project contained only 234 segments, a major goal of the design was to develop cost-efficient details to reduce the overall bridge cost. This goal was achieved by minimizing the number of variable depth segments, splitting the pier segments to reduce the maximum lift weight, using clean yet simple shapes for the box and specifying repetitive post-tensioning details.

The estimated construction cost for the precast segmental alternative was approximately five percent lower than the steel alternative. The segmental flyover bridge was built at a cost of $147 per square foot.

Minimization of Construction Impact on the Traveling Public

The Traffic Control Plan (TCP) was developed to minimize lane closures. The heavy skew of the bridge as it crossed the mainline of I-95 made it difficult to place segments without working over multiple lanes simultaneously. To address this issue, the TCP provided for multiple lane shifts on temporary pavement and restricted the extended lane closures to nighttime only. Segments were precast off-site and erected at night during hours of minimum traffic volume. This allowed the contractor to maintain the interstate mainline at its required operational level of service while meeting a very aggressive construction schedule.

Jury Comments

The use of precast segmental construction allowed the contractor to complete the structure during nighttime hours, lessening the impact to the traveling public. This project incorporates the owner’s latest durability requirements for post-tensioning systems to improve long-term sustainability and reduce life-cycle costs.