“The SR 69 Twin Bridge is a prefabricated bridge unit [PBU] project,” Harriman said. “We had double CT girders by precasting two girders under the concrete deck and setting it on the bridge foundation one PBU at a time. Setting these units only requires a small concrete closure placement. These PBUs can be manufactured with a four-inch thick partial deck — a normal deck would be eight inches thick. That allows these even lighter units to be set in place and the deck cast on top.