I-4/Selmon Expressway Connector – Tampa, Florida

The $426 million I-4/Selmon Expressway Connector provides a connection between Interstate 4 (I-4) and the Selmon Expressway in Tampa, Florida. This facility, which includes dedicated truck lanes, services approximately 10,000 trucks a day, reducing traffic on local city streets and improving safety. The Connector also provides additional route options for the traveling public, including convenient access to the Selmon Expressway from I-4, the Tampa cruise terminal, local beaches, Tampa International Airport, and flexibility for hurricane evacuation.

Innovation of Design and/or Construction

Innovations used in the design were:

External post-tensioning which allowed reductions in the web thickness, principal stresses in the web, required shear reinforcement, and overall cost of the cantilever construction.
Segmental concrete construction that significantly decreased the construction schedule.
Erection of highly curved flyovers with horizontal radii of 570 feet over I-4 using the balanced cantilever method with segment lifters instead of large ground-mounted crawler cranes.
Precast segmental construction method on highly skewed piers in the I-4 median to minimize cast-in-place construction.

Numerous innovative methods were used during construction to maximize efficiencies in safety, quality, and production, including:

Top down erection equipment with custom segment lifters (self-propelled beam and winches) built specifically for this project were used where there was insufficient space for traditional ground based erection cranes, resulting in reduced lane closures and detours.
Custom compact out-of-balance pier falsework towers combined with outboard stability prop towers were implemented to solve bridge construction challenges where existing features (structures, roads, railroads) were in close proximity of new bridge piers.
Temporary PT bar stressing blocks were implemented throughout the segmental superstructure to increase construction efficiencies, resulting in time and cost savings when demolishing cast-in-place blocks that required removal.
Bottom up concrete placement for construction of bridge piers using a high slump concrete and specialized formwork with valves spaced vertically along the column formwork.

Rapid Construction

Due to unexpected available funding, the consultants were asked to shorten Florida Department of Transportation’s (FDOT) original design schedule. The consultants added design resources, allowing the completion of all design work three months ahead of FDOT’s new schedule.

The original anticipated construction schedule was 1,065 days, which was 753 days ahead of the maximum 1,818 days in FDOT’s Request for Proposals. The project team accomplished this by using eight casting machines to accelerate the fabrication of the bridge components. As many as six drilled shaft crews and multiple substructure crews were implemented to expedite the construction of the foundation and substructure elements. For segment erection, five balanced cantilever erection crews working day and night shifts and one span-by-span erection crew were used to reduce the overall project schedule. These crews, combined with state-of-the-art erection equipment, including mobile segment lifters for top-down erection, greatly exceeded production cycles originally anticipated. In addition, top-down erection equipment was used to minimize the number of lane closures and detours, which resulted in reduced impacts to the traveling public.

Aesthetics and/or Harmony with the Environment

Nearly all of the required 75 right-of-way parcels involved remediation for contamination. Contamination cleanup, including remediation of dewatering operations, transpired concurrently with construction. The cleanup effort greatly enhanced the quality of the environment in and around Ybor City.

The project also included addressing impacts to McKay Bay Park, a valued Section 4(f) resource and environmentally-sensitive habitat for migratory shorebirds. A two-year coordination process with the City of Tampa and the Federal Highway Administration was required to obtain approval. The result was a reduction in pollutants discharging into the preserve. Stormwater management facilities were established to enhance untreated waters prior to entering McKay Bay and areas of Tampa Bay surrounding Port Tampa Bay.

The project team worked diligently with community agencies and business leaders to develop context sensitive and harmonizing architectural aesthetics which incorporated the brick and color patterns well established within the fabric of the Ybor City community, Palmetto Beach Historic Districts and Tampa’s McKay Bay Park. This includes the historically-themed exterior treatment the 7th and 4th Avenues Gateway underpass facades, the toll plaza gantry and supporting structural members, and the retaining wall panel facades throughout the project.

Cost Competitiveness

The estimated construction cost was originally $446 million. Through the alternative bid package process, the project was completed at a construction cost of $429 million, resulting in a net savings of $17 million.

Minimization of Construction Impact on the Traveling Public
The design teams preserved one bridge in the median of I-4 that was slated for demolition during a prior construction project. This bridge was used as construction access and also as a median diversion during construction of the bridges overhead, resulting in a reduced construction impact to the traveling public.

During construction, top-down span-by-span and balanced cantilever segment erection equipment and methods were implemented to minimize impact to the traveling public, the railroad, and to environmentally-sensitive areas of the project.

Overall, the community was extremely supportive of the project. FDOT received minimal complaints from the traveling public, nearby residents, or other parties during project construction.

Jury Comments

The project demonstrated how segmental construction can provide obstruction free, fast and flexible bridge erection in a highly congested urban/environment. The Florida DOT should be commended for allowing the designers and contracting team to take every advantage that segmental construction affords to orchestrate the building of this very complex urban interchange within budget and schedule.