The main spans of the Robert Moses Causeway consist of two anchor spans and one suspended span, which are made of steel trusses. The suspended span is about 467 feet long and is supported by four pin-and-hanger systems. These pins and hangers are to be replaced in kind. The maximum force for each hanger is about 600 tons.

CHI provided construction engineering services for Skanska Koch, and the main objective was to design jacking frames and temporary supports for replacing existing pins and hangers. In addition, the global stability of the truss spans was checked.

A global model was created for the anchor and suspended spans, and analysis was conducted for dead, live, thermal and wind loads. Furthermore, local finite element models were created for the areas adjacent to the jacking operation for
determining member stresses during construction. A step-by-step jacking and pin-and-hanger replacement procedure was also developed.