The underground Heritage Hall visitor center is directly adjacent to the historic 1879 Capitol building. The new center extends 40 feet below the existing building, which required extensive excavation and created unique site design considerations including foundational support and vibrational monitoring. A series of central skylights provide views of the historic dome from within the new building’s lobby.
Silman provided full structural engineering services from schematic design through construction administration. This involved working closely with the Michigan State Capitol Commission (MSCC), the geotechnical consultant, and the contractor to design a permanent earth retention system against the existing building. Specifying, installing, and monitoring a vibration and movement monitoring program ensured that the historic structure and surrounding landscape were not adversely affected by the close proximity of excavation.
The design also required close coordination with the architectural and landscape teams since the visitor center’s roof supports a fire lane access road and extensive vegetation. Silman additionally consulted on the structural and site implications of new street level parking and site stairs that provide pedestrian access between the lower street level and the higher landscape around the Capitol.
This project was completed using the Design-Build project delivery method.