Most visitors, students, and staff using the pedestrian mall at the heart of the University of Wisconsin-Madison do not know there is a passageway under their feet. It’s a walkable tunnel corridor supplying the steam, chilled water, compressed air, signal, and electrical services crucial for daily life on campus.
The 10- by 12-foot tunnel runs for 1,800 feet. Designing the tunnel required carefully locating existing underground utilities, routing the tunnel to best use existing utilities and accommodate updated utilities, coordinating among service providers, and updating utilities as needed. All while creating as little disturbance as possible to pedestrian and vehicular traffic.
The tunnel runs beneath West Johnson Street and University Avenue, and the City of Madison stipulated the busy streets could not be closed for construction. H-pile structures were driven into the ground to support bridge decking that would carry traffic during construction. Pavement on University and Johnson was removed and then repaved with a bridge deck atop the H-piles. The bridge decks were used during two years of construction and then removed and replaced with colored concrete.
As a subconsultant to Affiliated Engineers, Inc., Ayres provided survey, civil utility design, traffic control, and construction services.