Bridge Bundling Promotes Streamlined Delivery

by Sadie Dalton, HNTB project manager

In southwest Florida, near the Big Cypress National Preserve sits Immokalee, a rural agricultural community in Collier County that is home to a network of bridge structures built in the late 1940s and early 1950s. These 11 original timber foundation bridges—vital access points for commercial, agricultural and residential traffic to the community—required replacement after years of repairs and increasing maintenance costs.

Heading design and supporting procurement for construction, HNTB collaborated with Collier County to utilize a bridge bundling model. Grouping the bridges by structural similarities in a shared geographic locale into a single design contract and four construction packages allowed the county to foster a new level of efficiency and cost-effectiveness with infrastructure delivery. This approach expedited the design, streamlined construction timelines and minimized disruptions to the surrounding ecosystem.

• Expedited Approach to Design: Bundled into a single design contract containing bridges across three corridors, the project team was able to group bridges with similar sections and span lengths to facilitate a consistent and seamless approach to designing the replacements. While one structure had unique parameters, the team was able to design three total span lengths and associated beam designs to accommodate the other 10 bridges. These designs introduced economies of scale and facilitated construction activities. This approach also supported the county’s ability to keep the old bridges operational through construction, minimizing road closures or detours.
• Streamlined Construction Timelines: With multiple sites under construction simultaneously and assigned to different contractors, the bundling project ensured there were enough workers to complete the construction efficiently and on schedule. Divided into four construction packages, the county was able to attract more interest from local contractors. This was especially productive in improving the procurement of materials and services as well as reducing delivery costs to the remote worksites.
• Minimized Disruptions to Ecosystem: Due to the project’s proximity to the Big Cypress National Preserve, special environmental considerations were taken into account including extensive wildlife and species studies, restricted construction timing, wildlife fencing and dry pathways, as well as creative construction staging to minimize wetland impacts. Early in the design process, the project team coordinated closely with the U.S. Fish and Wildlife Service and Florida Fish and Wildlife Conservation Commission to ensure the protection of species was considered during design, permitting, and construction.

Beyond preserving the economy and safety of the county residents, the new bridges were designed with future connectivity and roadway improvements in mind. Future roadway improvements will easily tie into the new lane and shoulder widths, while the bridge closest to Immokalee can seamlessly tie into planned sidewalk improvements promoting safer routes for pedestrians in the area.

Each bridge was elevated to allow better flow underneath. This additional clearance makes the openings more inviting to wildlife, ideally providing a safer alternative to crossing roadways.

The incorporation of prestressed concrete piles enhanced foundation longevity, while safety measures such as paved shoulders, crash-tested traffic railings and improved guardrails were integrated to elevate roadway safety standards.

Recognizing the variables across the 11 locations and the proximity to commercial and community property, the project team expanded its public involvement methods to engage stakeholders, including the city of Immokalee, Immokalee Regional Airport, the agricultural community, local businesses, residents and elected officials.

“Creating safe and reliable transportation infrastructure is vitally important for Collier County,” said Collier County Commissioner William L. McDaniel, Jr., District 5. McDaniel is the commissioner in the area where the Eleven Bridge Replacements project occurred. “HNTB’s expertise in bridge design helped us create a resilient solution that was completed with minimal disruptions to daily life and to the surrounding environment that is unique to our community,” McDaniel added.

A testament to the collaborative infrastructure approach, the Eleven Bridge Replacements bridge bundling project provided a streamlined, holistic solution that benefits the entire community. Now completed, this restored network of bridges is improving mobility, reliability and safety for Collier County motorists, thereby supporting the economic vitality of the region.