ROGERS BRIDGE PARK PEDESTRIAN BRIDGE
The Rogers Bridge Park Pedestrian Bridge offers pedestrians and cyclists the opportunity to cross the Chattahoochee River between Duluth and Johns Creek. The bridge connects Duluth’s Rogers Bridge Park to Johns Creek’s Cauley Park and is a replica of the original structure built in 1912 and abandoned in 1978. Years later, the bridge became the focus of a 2006 proposal, leading Gwinnett County to commission a structural integrity study. Public input was gathered on the options that derived from the study. After evaluating stakeholder needs, expanded public access, and low projected maintenance costs, officials determined that replacing the bridge was the best course of action.
United Consulting conducted a Bridge Foundation Investigation (BFI) following GDOT and AASHTO LRFD guidelines. The primary challenge was the presence of soft, potentially liquefiable soil near the river. To assess subsurface conditions, Our team of experts performed six standard penetration test (SPT) borings and two straight auger borings, for retrieving undisturbed Shelby tube samples from deep soil strata. Four borings were placed near the proposed bent locations, while at the two river-adjacent bents, rock coring was performed after auger refusal to evaluate its foundation support quality. The remaining two borings were positioned at staging areas on either side of the river. Laboratory testing, using the Unified Soil Classification System (USCS), analyzed soil composition that included grain size, liquid limit, and plasticity index. Each of these soil parameters affects the installation methodology and predicted performance of the deep foundations. In addition to soil analysis, our team of experts conducted compressive strength and elastic moduli testing on the cored rock. The data collected was applied to computer programs to predict the performance of the recommended deep foundations, ensuring proper pile driving and avoiding overstressing during installation. These programs also provided data on the overall pile and drilled shaft capacity for each bent. United Consulting also conducted limited construction materials testing, including soil density tests beneath the bridge and approach slabs, as well as concrete cylinder break tests.
Our team of experienced engineers recommended using two different types of deep foundations to support the proposed bridge. Drilled shafts were recommended for the two intermediate bents adjacent to the river where most of the bridge’s weight would be supported. Although they’re more expensive to construct, drilled shafts are better suited for river-adjacent locations where pile footings are impractical. For the end bents, we explored more economical foundation options and recommended driven steel H-piles, which can be installed with a crane-mounted hammer at significant cost savings compared to drilled shafts. Given the site’s soil conditions, United Consulting’s analysis also considered the potential down-drag load affecting the piles and drilled shafts capacity after installation. Therefore, the pile driving plan included the down-drag loads caused by soil consolidation around the piles, a critical factor in ensuring foundations successfully perform as designed.
The City of Duluth received the 2024 Project of the Year award from the American Public Works Association (APWA) for its Rogers Bridge Project. The award was given in the Structures category for projects valued between $5 million and $25 million. The City has received multiple accolades since the grand opening of the bridge in 2023.
