S.S. Badger Carferry Lifting Tower Emergency Repairs

Background

The S.S. Badger, also designated as US Highway 10 crossing Lake Michigan between Ludington, Michigan and Manitowoc, Wisconsin provides a vital transportation link from mid-May through mid-October each year. One of the Ludington, MI lifting towers for the apron that gives access to the S.S. Badger failed suddenly in July 2023, suspending seasonal trips indefinitely. The Interlake Steamship Company (Interlake), which owns and operates the S.S. Badger and the Michigan Carferry Service, engaged Foth immediately to perform engineering design and permitting for a new lifting system to restore the Carferry service. Foth had provided structural inspection, grant funding support, engineering and construction support for the S.S. Badger’s docking facilities in the past and understood the need to work swiftly to re-establish their operations. Interlake’s goal was to have the S.S. Badger back in service for the 2024 shipping season.

Approach

Based on historical drawings, the existing transfer apron and lifting tower system were built in the 1930s with open hearth steel. The lifting system consisted of two lifting towers, one on each side of the apron. Each lifting tower was a steel lattice structure with a cantilever beam connected to a counterweight and the transfer apron. The lifting towers were supported on a concrete pile cap on timber piles. Foth’s design began with a bathymetric survey, geotechnical investigation, and an analysis of design requirements.

Our team originally proposed a new lifting structure constructed of 36” diameter steel piles, supporting a lifting beam platform and hoist. To ensure synchronization, the new lifting structure was proposed to be installed on both sides of the apron. This design included an 80-ton hoist on each side to lift the 120-ton ramp. Due to project timing requirements and material sourcing, 80-ton hoists were eliminated as a viable solution. The revised design included a smaller, 15-ton hoist and a counterweight system per side, similar to the original design, but more modern.

Connection of the new lifting tower cable systems to the existing apron posed a challenge because the existing apron lifting connection included a toggle pin in a transom beam constructed of nearly 100-year-old open hearth steel. Foth had concerns about modifications to the existing apron transom beam due to the age of the steel. Our team solved this challenge through the design of a new lifting beam with eye bar connections to the existing toggle pin. A steel collar around the existing apron transom beam with safety chains connecting to the platform above was designed as a safety stop. The final design included two additional 24-inch diameter steel piles placed on each side of the front piles for additional structural support.

Permitting activities began with state and USACE staff communications to establish the required permits and discuss the importance of obtaining quick approval for the start of emergency repair activities. Foth worked closely with the agency representatives to address questions and design changes that allowed the permit applications to quickly move forward.