This is the first underpass ever installed by Dakota County. The county was reluctant to build it at the time, but now they commonly use tunnels under busy roads.
The underpass was built in 1993 when the county widened Diffley Road. Their plan was to change the road from 2 to 4-lanes with a fifth center turning lane and bike trails on both sides of the road. The Caponis worked for over a year with planners from the city of Eagan and Dakota County to make sure the underpass was built and to limit the damage the changes made to the art park. Without this there would be no way for park visitors to safely walk from one side of the park to the other and noise from the road would interrupt events in the amphitheater. The compromise was to remove the center turn lane and the bike trail on one side of the road, and for the Caponis and the city of Eagan to split the cost of the underpass.