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Wekiva 3B Major Bridge

This award-winning project will serve as a valuable case study for future use by the engineering profession to illustrate a better solution compared to more traditional interchange configurations.

FBT served as the lead structures subconsultant on this project for FDOT District 5 and served as the Structures Engineer of Record for the two bridges in this contract.  The project included the flyover bridge and a short bridge over a local road (Pond Road).  Section 3B of the Wekiva Parkway (SR 429)/SR 46 Realignment Project is the western-most section of the SR 46 Realignment Project within Lake County.  The SR 46 corridor provides the connection to key transportation routes such as the Wekiva Parkway, Interstate 4, and the entire beltway system around metropolitan Orlando.


The project converted the existing diamond interchange at US 441 over SR 46 to an at-grade intersection by providing a new flyover bridge to accommodate the heavy traffic volumes from southbound US 441 as vehicles enter the SR 46 corridor and connect to the Wekiva Parkway. The owner of the bridge is FDOT District 5 and the FDOT Central Office provided the oversight of the Category 2 Bridge design. The General Contractor was GLF Construction Corporation. This project won the Best in Construction Award for Major Bridge from the Florida Transportation Builders’ Association.

Since the project is located immediately adjacent to residential neighborhoods within the City of Mt. Dora, innovative considerations were made regarding the layout and aesthetics of the interchange.  The City of Mount Dora required the lowest possible profile for the proposed interchange and this project avoided a typical 3-level interchange. The concept plans from the study phase required a 1593’ long flyover eccentric to the at-grade intersection. In the diamond interchange configuration prior to construction, US 441 was at the original grade atop a hill and SR 46 was in a cut section under US 441.  The long flyover from the study phase crossed over US 441 and SR 46 at a higher elevation.  


The innovative changes proposed by the team during the final design phase included spanning directly over the intersection to shorten the flyover bridge rather than be eccentric to the intersection.  Then by lowering the profile of US 441 to match SR 46, the profile of the bridge was lowered to minimize impacts to adjacent residences.  To further reduce the structure depth of the bridge, a steel trapezoidal box girder option with integral piers was used. The construction required removal of the existing diamond interchange bridges with traffic detoured onto the existing at-grade ramps.  A traffic analysis indicated the new at-grade intersection under the bridge will function at a good level of service because the bridge removes the heaviest directional traffic volume from the signal phasing of the intersection.

Wekiva 3B developed elevation plans
Wekiva 3B Major Bridge plans

By completely revising the geometry of the flyover bridge from the study phase the project was greatly simplified, saved a significant amount of time and money, and greatly reduced impacts to the adjacent residential properties in the City of Mt. Dora. The completed project represents an elegant solution that satisfied the many different project constraints.

This structure is a Fracture Critical Category 2 structure which required an independent peer review and FDOT Central Office review. The independent peer review was performed by BCC Engineering. The integral steel box diaphragms required the longitudinal box girders to align geometrically and provide access for maintenance throughout the limits of the structure. The box internal cross bracing and horizonal truss members required accommodating the interruption for the diaphragm top flange as well as the jacking and bearing stiffeners. Field splices were included immediately adjacent to the integral steel box diaphragms to allow the diaphragm boxes to be shipped in one piece. The uplift forces from the shortened end span arrangement were balanced by the stiffness of the integral box diaphragm, and the longitudinal and transverse bending stresses necessitated the need to check the principal two-way stresses in the diaphragm top flange. The fracture critical diaphragm called for High Performance Steel (HPS) Weathering Material with extra toughness.

Wekiva 3B Bridge Framing Plan
Wekiva 3B Pier Segments Supported by concrete column
One-Piece Pier Segments for Longitudinal Box Girder Integral with Steel Diaphragm

Pier Segments Supported by

 Concrete Column

One-Piece Pier Segments for Longitudinal Box Girder Integral with Steel Diaphragm

This structure incorporated intersection signing and signals on the bridge to supplement the mast arms for the intersection beneath the bridge. A permanent Bat Abode was mounted between the box girders to be inhabited by the environmentally protected bats that were present in the original bridge. The bats were humanely excluded from the original bridge prior to demolition. The Bat Abode had to be in a portion of the bridge with reduced live load deflections (near a pier).  The box girders met the aesthetic requirements of the City of Mount Dora along with a rustic weathering steel look that met the Wekiva Parkway Aesthetic Master Plan requirements.


The color schemes and textures with recessed form liners were also a requirement on the columns and window railings. The construction cost for this project was $32.8 million dollars and estimated construction duration was 850 total days. The total continuous structure length of 471’ was a vast improvement compared to the concept plans from the study phase that required a 1593’ long flyover eccentric to the at-grade intersection. The revised scheme allowed the use of much less costly MSE wall and embankment for most of the ramp’s length rather than the longer bridge. This reduced the overall project cost by over $3 million and eliminated several months of construction time.

Wekiva 3B Bat Abode Mounted Under New Bridge

Bat Abode Mounted

Under New Bridge

Traffic signals and signs mounted on bridge

Traffic Signals and Signs

Mounted on New Bridge

It was important to the Mt. Dora City Commission and FDOT that the interchange does not feel like an interstate roadway was constructed in the resident’s back yards.  Not only did this structure eliminate the need for a 3-level interchange, but it also further reduced the profile by up to 10’ with use of an innovative integral diaphragms with trapezoidal box girders when compared with a more traditional use of steel plate girders supported on top of hammer head concrete pier caps.  


By revising the geometry of the flyover bridge the project was greatly simplified, saving a significant amount of time and money, and greatly reducing impacts to the adjacent residential properties in the City of Mt. Dora.  The shorter and more compact bridge is significantly less intrusive to the adjacent residents, yet still provides full functionality of the original concept from a traffic perspective. The project won FTBA's 2021 Best in Construction Award for the Major Bridge Category and ASCE East Central Branch's Project of the Year.

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