Chain of Rocks Bridge - Missouri

Foundations

Jul 2

Power | Foundations | Bridge Infrastructure | Missouri | Illinois

Project Summary

With an emphasis on replacing aging critical infrastructure, the new I-270 Chain of Rocks Bridge is being constructed parallel to the existing 1966 structure. Its mission is to enhance the daily commute for the 51,000 vehicles that traverse it, offering a faster and safer journey. Upon completion, it will boast ample width to cater to the envisioned six lanes. The project scope includes 60 drilled shaft foundations, each featuring 10-foot diameter shafts with rock sockets. Additionally, permanent steel casing was installed at varying depths, ranging from 30 to 95 feet, to provide robust support for the bridge's piers.

Executing this project involved meticulous pre-planning, close collaboration with Subject Matter Experts (SMEs), and ongoing communication with the general contractor, engineering firms, and various trade partners integral to the project's execution.

The site's proximity to the Mississippi River necessitated drilling under fluid to counteract sand and silt intrusion into each shaft. The solution utilized nearly 46,000 gallons of fluid mixed with a polymer, forming a flocculant that effectively minimized sediment accumulation.

Efficient manipulation of the extensive rebar cages, measuring 8 feet in diameter and spanning 100 to 115 feet in length, required meticulous coordination with the general contractor's engineering team. Tailored lift plans were devised for each shaft location, necessitating frequent weekly meetings to ensure a secure and high-quality installation. This rigorous planning encompassed even the smallest details, such as the inclusion of an engineered collar to ensure proper hoisting through tandem picks.

For the installation of permanent casing and rebar cages across the project, a strategic choice was made to employ two 230-ton crawlers. This approach ensured the careful handling of the load, guaranteeing the integrity of the cages during the hoisting process.

The eastbound bridge foundations are complete, and westbound construction will resume in 2025. The new Chain of Rocks Bridge is scheduled to open in 2026.