Located in the 1,500-acre Chicopee Woods Nature Preserve in North Georgia, the Elachee Nature Science Center is an education center that serves more than 35,000 students from over 35 school systems and an additional 30,000 visitors to the museum and preserve each year. The facility has hiking and biking trails, a nature shop and exhibits at the science center, which also hosts conservation-related and educational programs in addition to weddings and other events. The center is accessible by a single bridge that carries Elachee Drive over Interstate 985 (I-985) in Gainesville, Georgia. The original bridge was built in 1967 and had reached the end of its lifespan. As part of the GDOT Bridge Replacement Program, the Georgia Department of Transportation (GDOT) identified the Elachee Drive Bridge over I-985 to be replaced due to its structural deficiency. The existing structure also did not feature any sidewalks, bike lanes, or safe crossings for pedestrians and cyclists traversing the network of trails throughout the nature preserve on either side of the crossing, including the Chicopee Woods mountain bike trails. To deliver the project, GDOT partnered with Michael Baker International, the lead design firm in charge of project management, structural design, and environmental permitting; Holt Consulting Co., LLC, the roadway design firm; Robert and Co. the lighting design firm; and Confluence Design Consulting, the architectural design firm. The new bridge is 254 feet long with a total deck width of 45.5 feet. The structure consists of two 11-foot travel lanes, with a 2-foot gutter, 8.5-foot sidewalk and 4-foot bike lane on the north side, and a 6-foot rural shoulder on the south side that can also accommodate bikes. The bridge was constructed in one stage on an offset parallel alignment to the north of the existing bridge, allowing for continual traffic flow through the duration of the project. Notably, the project was originally scoped as a standard concrete bridge replacement with no aesthetic enhancements. However, there was a desire from the City of Gainesville to utilize the bridge as a gateway to the city. I-985 links the Atlanta metropolitan area to Gainesville, and the Elachee Drive over I-985 Bridge was an ideal landmark to welcome visitors and the city’s 43,000 residents alike. The Michael Baker team quickly pivoted to include decorative enhancements funded by the city during the bridge’s design phase. These bridge enhancements followed Gainesville’s branding scheme, which included decorative fencing on the bridge that was designed with a wave pattern and matches the city’s color scheme, stone facing and City of Gainesville lettering on the center bridge column, and a large illuminated "G" logo on the outside of the bridge. While the bridge was designed to incorporate these additional elements, it was also designed to allow future lighting enhancements to the decorative fencing on the bridge by the City of Gainesville requiring minimal costs and no bridge reconstruction. Throughout the project’s design and construction, the team was met with several challenges. Design started prior to and continued
throughout the COVID-19 pandemic, and material costs had increased significantly because of the supply chain disruption. Lighting for the decorative fence was included in the final design, however, when costs increased and the city did not have the funding for the lighting, the Michael Baker team had to remove these items near the end of the design phase while still allowing for future lighting. The team worked together to identify budget efficiencies while also incorporating the change in scope brought about by the request of including architectural elements. In addition, the Michael Baker team worked to keep the project schedule on track, even with the additional elements included, and the bridge was completed on time and on budget. The project necessitated close coordination and collaboration among a long list of stakeholders—including GDOT, the City of Gainesville, the Elachee Nature Science Center, Chicopee Woods Area Park, engineering consultants and more. As the lead design firm, Michael Baker made the goals and needs of each stakeholder a priority. By listening to each stakeholder and thoughtfully assessing the feasibility of those asks, Michael Baker was able to prioritize requests in a way that all parties benefitted. The City of Gainesville also had a set of stakeholders that their staff managed, and the Michael Baker team worked to ensure their feedback was incorporated as well, without delaying design or construction. Geotechnical challenges arose during the project’s final design phase. The structural bridge foundation on one end of the bridge included steel piles driven into shallow, highly fractured, partially weathered rock. As part of this project, the GDOT Office of Materials and Testing required specific driving criteria for the end bent steel H-piles being installed in pilot holes. A load test was performed on an end bent pile after installation and the pilot holes were filled with concrete. The load test was used by GDOT to develop driving criteria for future projects with similar foundation conditions. The land within the project site needed to be cleared to prepare for the new bridge. Trees were removed to allow for construction activities and the bridge itself, but the project’s environmental engineers and project managers remained dedicated to limiting the ecological impact as much as possible during the build. The Elachee Nature Science Center partnered with New Urban Forestry to protect and encourage tree health and growth in prioritized areas within the preserve. Certified arborists identified at-risk tree groups and treated the root sections with sucking-insect basal treatments, soil care and injections, phytophthora treatment and more to support the trees. Today, the eye-catching new bridge carrying Elachee Drive over I-985 provides a warm welcome to the City of Gainesville, while simultaneously offering a safe passage for visitors to the Elachee Nature Science Center and Chicopee Woods Nature Preserve. The project serves as an example of how a standard concrete bridge replacement can be enhanced for the local community and local government with minimal cost and impacts to the project schedule.
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