Innovation on the Loxahatchee River

By Steven Shaup, Contributing Author

The Loxahatchee River Movable Bridge Rehabilitation is a case study in innovative engineering, construction and multi-stakeholder collaboration. The bridge, part of the Florida East Coast (FEC) Railway corridor, is critical in linking South and Central Florida, supporting Brightline's high-speed passenger rail and substantial freight traffic. 

Originally built in the 1920s and part of Henry Flagler’s historic railway, this structure required extensive modernization to meet 21st-century demands.

The $62.3 million project, driven by Brightline as part of its $2.7 billion Orlando expansion, evolved from an initial rehabilitation plan to a complete structural overhaul of the bridge located in Jupiter, Fla. Adaptive planning preserved essential components while addressing deteriorating conditions and modern transportation needs.

GFT was the lead designer for fixed and movable span elements, tackling structural, mechanical and electrical systems. 

The project aimed to extend the bridge’s life and reestablish its dual-track capacity to meet modern standards. The bridge, which spans 584 feet and once carried two tracks, had seen the west track fall out of use over the decades. Reviving this dual functionality was central to accommodating increasing rail demands.

Innovation in Design, Construction

A defining challenge of the project was executing construction around an active rail line without significant service interruptions. The corridor is vital for transporting freight, so project planning had to accommodate continued rail and marine traffic. Preassembled components—such as the bascule span installed in three pieces—enabled fast, precise alignment under constrained outage windows.  

Installation occurred during tightly managed outages: an initial 24-hour rail and 36-hour river shut down to remove the existing bascule span and a 48-hour complete track shutdown with a 72-hour navigation closure to complete the installation. A temporary “jump span” facilitated an unrestricted freight schedule and limited marine traffic between these outages.  

Substructure units were fabricated for installation around and through the operational track, capitalizing on brief train-free periods. Additional small boat navigation relief was provided via a newly designed through-plate girder span that allowed many of the common river vessels to pass beneath the bridge during normal operations, thus reducing waterway delays.

Adaptive Engineering

The plan to strengthen existing girders quickly shifted to a superstructure replacement when inspections revealed the steel could not be adequately rehabilitated to carry the required design loading. 

After fabrication of the replacement girders had started, a further complication arose when it was determined a substructure redesign was needed. The redesign necessitated the construction of new approach span piers because replacing the superstructure on the original timber-pile-based piers with unknown pile depths posed a risk of future concrete deterioration and scour, affecting long-term operations. 

In coordination with Brightline, the nation’s only privately owned and operated intercity passenger railroad company, and the contractor, modern large-diameter open steel pipe piles filled with concrete were chosen for the strength, durability and speed at which they could be installed. 

To ensure long-term resilience, the piles were installed to depths exceeding the projected 100-year scour, which ranged from 13 feet to 27 feet. 

By the time the strategic pivot to a substructure replacement occurred, much of the structural steel had already been fabricated. The team ingeniously integrated these pre-purchased girders into the revised design, developing short transition spans adjacent to the bascule and rest piers to reduce loads on those piers that were to remain and to reuse span lengths.

Geotechnical Uncertainty

Soil conditions under the Loxahatchee River proved highly variable, complicating the installation of new piers. Pile Driving Analyzer (PDA) testing revealed unexpected subsurface behavior that resulted in driven capacities not meeting design requirements, triggering redesigns at multiple locations. 

The team adjusted pile diameters, spacing, and depths to align with site-specific conditions while maintaining the construction schedule.

The presence of active rail lines above certain pile locations intensified the challenge. In some cases, piles had to be driven between live rails, demanding exceptional coordination and safety precautions.

Sequencing and Execution

Careful planning was required to manage scheduling constraints. Design documentation emphasized minimizing downtime for rail and marine users. Within this framework, contractors were empowered to develop their efficient methodologies. 

The contractor devised a removable jump span to be flown in and out twice daily by crane over the 45 days between the two primary track and waterway outages. This limited the time the track and waterway were completely shut down yet still provided some measure of daily access for marine traffic during the span replacement phase. 

Safe Transitions

The permanent bascule span was installed section by section, supported by A-frame structures, with all systems aligned and fitted during preplanned outages.

A particularly complex sequence involved the on-site alignment and connection of the bascule span’s heel and toe ends. The team conducted precise preassembly trials to predict deflection behavior, ensuring seamless installation within the short outage windows. Despite minor challenges with on-site alignments, such as adjusting the span lock system, these efforts culminated in a smooth, safe, and on-time transition to the new system. 

Retaining parts of the original bridge required detailed analysis and compliance strategies. Modern load demands, mechanical system dimensions and safety codes had to be reconciled with infrastructure designed nearly 100 years ago.  

The project reused the abutments, bascule pier, and rest pier while replacing the remaining approach piers. 

Approaching the Spans

As part of the substructure redesign, engineers shortened the two spans on either side of the bascule span using transition segments to reduce structural stresses on reused bascule and rest piers. The redesigned span arrangements ensured original piers were not subjected to loads beyond their 1920s-era capacity.

The approach spans were assembled on-site and flown into position via crane during the primary track outages and during short-term outages that did not significantly impact rail operations. 

In contrast, the “small boat span” was constructed on temporary rails beside its final location and slid into place on a single weekend. These efforts exemplified the project’s logistical precision and strategic use of preassembly.

Economic and Environmental Impacts

The project removed a significant bottleneck along the corridor, improving the reliability and capacity of freight and Brightline’s intercity rail service. By enabling two-track functionality, the bridge increases throughput and creates redundancy—which is critical for high-frequency rail operations. 

From an environmental perspective, promoting rail over road transport supports sustainability goals by reducing highway congestion and associated emissions. The upgraded bridge also accommodates predicted storm surge, enhancing regional resilience. 

Stakeholder Coordination

The Loxahatchee River Moveable Bridge Rehabilitation required proactive collaboration between Brightline, the FEC Railway, the contractor, the U.S. Coast Guard, and GFT. Decision-making had to be swift, especially in response to design pivots, geotechnical issues and tight outage windows.

Stakeholders worked under a unified framework that emphasized open communication and shared problem-solving. This cooperative model proved essential in keeping the project on schedule and within revised budget expectations, even as the scope expanded significantly.

The Loxahatchee project serves as a model for approaching aging infrastructure by balancing component reuse with a selected replacement that allows for continued reliable use for the long term. It also illustrates the value of preplanning, modular construction, real-time engineering support, and agile project management.

As the demand for high-speed rail and efficient freight networks continues to rise, infrastructure projects like the Loxahatchee Bridge Rehabilitation highlight the importance of forward-looking investment. The project's success underscores how existing assets can be revitalized to meet new challenges without total replacement, maximizing value and minimizing disruption.

Moving Forward

Rehabilitating the Loxahatchee River Movable Bridge depended on engineering ingenuity and logistical prowess. The bridge was transformed from a single-track bottleneck into a dual-track link in Florida’s expanding rail network through careful design, adaptive construction methods, and strong stakeholder collaboration.

What began as modest rehabilitation grew into a landmark infrastructure upgrade that now supports economic growth, sustainable mobility, and maritime accessibility. 

It’s a powerful reminder: with the right team and the right approach, even a century-old bridge can carry the future forward. RB

Steven Shaup, P.E. is principal/senior vice president, Florida area leader – operations at GFT.