The Three Sisters are self-anchored suspension bridges and are significant because they are the only trio of nearly identical bridges—as well as the first self-anchored suspension spans—built in the United States. Over 720 bridges link the city districts. The Sixth Street Bridge's piers were built with arched openings beneath the river bed in order to accommodate future subway tunnels, following the recommendation of transportation planner Bion J. Arnold. The North Shore Connector tunnels completed in 2012 did not make use of this provision, but were bored further west (downstream) and do not pass beneath the bridge. The bridge was renamed on August 6, 1998, as part of a compromise after the Pirates sold the naming rights to PNC Park to locally based PNC Financial Services. Before the naming rights were sold, there was hugely popular sentiment in Pittsburgh to name the park itself after Clemente. It is closed to vehicular traffic on Pirates' and Steelers' game days, providing a pedestrian route to PNC Park and Heinz Field. When PNC Park was built, a statue of Roberto Clemente, originally erected at Three Rivers Stadium, was placed at the southeast corner of the park, right at the north anchorage of the Roberto Clemente Bridge. The Pittsburgh History and Landmarks Foundation in cooperation with the Riverlife Task Force, the City of Pittsburgh, and Duquesne Light Company, funded and managed the architectural lighting of the bridge. On November 20, 2002, the bridge was lit for the first time.