SR-67 Emergency Bridge Repair

When Hurricane Helene damaged the superstructure foundation of a historic bridge over the Doe River in Elizabethton, TN, Michels and our progressive design-build partner Dan Brown & Associates developed and executed a two-step plan to temporarily stabilize the 1929 bridge and install a robust permanent foundation under the compromised portion.

During the hurricane, two footings at Pier 3 experienced settlement due to erosion. This structural shift caused a 70-foot section of the bridge deck surrounding Pier 3 to subside by as much as 5 inches. Since pre-event deck elevations were not available, a survey of the existing deck was conducted to establish as-built elevations. To restore the bridge deck to its original profile, Michels used a synchronized lifting system, which recovered the full 5 inches of displacement around Pier 3.

Due to the complexity of the jacking process, Michels performed a seven-point sequential lift of the structure. The shoring system, which consisted of 14, 200-ton jacks for the elevation of the bridge and 20 100-ton jacks to keep the shorting in place, was secured after each cycle. Through its controlled pressurizing and monitoring computers located in the panels, the control panel oversaw all hydraulic components, allowing Michels to customize and adjust lifting activities in real time.

Once the bridge was stabilized, Michels used a low-overhead drill rig to install eight micropiles and a vertical drill rig to install 20 micropiles into cobble under the Doe River to support the bridge’s superstructure.