Utility tunnels underneath the University of Arizona are in dire need of a makeover. Some of these tunnels are 80 years old and suffer from cracked concrete due to water damage and rusting steel reinforcement bars. But how can you repair a vast network of utility tunnels without digging trenches and disrupting life above ground?

A carbon fiber lining developed at the University of Arizona to help retrofit buildings and structures against earthquakes is being used in a pilot project to restore and reinforce a utility tunnel ten feet below the campus. The wrap may look like wallpaper to the untrained eye, but the carbon fiber mats soaked in epoxy resin are far from it. The mats cure in about a day and once dry, will turn into a rigid lining help fortify the tunnel. Applying the wrap and fixing the tunnel from the inside offers a minimally invasive solution.

“We are applying carbon fiber-reinforced polymer to strengthen the tunnel ceiling,” said Mo Ehsani, professor emeritus in the College of Engineering, who pioneered the concept of repairing and strengthening existing infrastructure with fiber-reinforced polymer in the late 1980s. “Even though these mats are applied like a fabric, they provide the equivalent of 1-inch steel bars placed a foot apart inside the tunnel.”

The project is a collaboration involving UA Planning, Design and Construction, UA Facilities Management and Ehsani’s company, QuakeWrap.