Sawmill Creek Pedestrian Bridge Replacement

Challenges:

1. Bridge Destruction: The loss of the pedestrian bridge cut off access to the multi-use trail, which was an essential part of the Waterfall Glen Forest Preserve. This disrupted public access for hikers, cyclists, and other outdoor enthusiasts.
2. Recurring Ice and Debris Issues: The original bridge, with its low elevation, had a history of ice backups and debris accumulation, which contributed to flooding and damage to the infrastructure.
3. Temporary Solution: A temporary bridge was installed in August 2022, ensuring continued public access while the design and permitting process for a permanent replacement took place. However, this was a stopgap solution, and a more permanent, resilient bridge was required.
4. Design and Permitting: The new permanent bridge needed to address the flooding and ice issues, as well as meet environmental standards. The design process involved careful coordination with stakeholders, engineers, and environmental experts to create a long-lasting solution.

Solution:

In response to the challenges, the District took decisive steps to ensure the replacement bridge would meet safety, functionality, and environmental needs:

1. Public Bid for Construction: On April 10, 2023, the District initiated a public bid for the construction of the permanent pedestrian bridge. The selected contractor would be tasked with delivering a structure that was not only resilient to high-water conditions but also aesthetically appropriate for its location within the scenic Waterfall Glen Forest Preserve.
2. Bridge Design: The new bridge was designed with enhanced resilience, elevating the structure to reduce the risk of ice and debris backups. It was a 15’ 4” wide x 1 span, 65’ 10” long pedestrian bridge, designed to accommodate a variety of trail users safely. The superstructure features a robust 8” cast-in-place concrete deck supported by 24” Valmont U-BEAM Tub Girders, providing a sturdy and durable solution that would withstand the creek’s fluctuating water levels.
3. Public Safety and Continued Access: Throughout the design and construction phases, the priority was to ensure continued public safety and access. The temporary bridge, while not ideal, allowed trail users to continue enjoying the preserve during the interim. The new design aimed to be an enduring solution that minimized future disruptions.
4. Environmental and Aesthetic Considerations: The project took into account the environmental sensitivity of the Waterfall Glen Forest Preserve. The new bridge design was intended to blend seamlessly with the natural surroundings while providing the necessary structural integrity to handle high-water events and debris.

Outcome:

The permanent bridge is set to replace the damaged structure, providing a safer, more resilient crossing over Sawmill Creek. The design, with its elevated superstructure and durable materials, ensures the new bridge will be able to withstand the creek’s challenging conditions, including ice buildup and flooding. The bridge’s 15’ 4” width and 65’ 10” length make it suitable for all types of multi-use trail users, from pedestrians to cyclists.

As of now, the public bid process for the permanent construction is nearing completion, and the selected contractor will begin work soon. The District’s efforts to maintain public access while addressing the underlying infrastructure issues reflect a forward-thinking approach to preserving and enhancing the Waterfall Glen Forest Preserve for future generations.

Lessons Learned:

• Proactive Temporary Solutions: Installing the temporary bridge in August 2022 ensured that public access remained uninterrupted while the design and permitting process for the permanent bridge was underway.
• Collaboration with Stakeholders: Involving environmental experts and local stakeholders in the planning and design of the bridge ensured that the project balanced safety, functionality, and ecological concerns.
• Elevated Design for Long-Term Resilience: Elevating the bridge’s elevation and using durable materials like the Valmont U-BEAM Tub Girders ensures that the structure will be resilient to future high-water events, while minimizing the risk of ice and debris accumulation that plagued the original bridge.

This project underscores the importance of planning for the future of infrastructure in sensitive environmental areas. By considering the long-term functionality and environmental impact, the Sawmill Creek pedestrian bridge replacement is poised to provide a lasting solution for the community and the preserve.