A 2006 study determined that Pittsburgh has 446 bridges, and with its proximity to three major rivers and countless hills and ravines, Pittsburgh is known as "The City of Bridges". Pittsburgh is the world record holder for bridges with piers and stands contained entirely within city limits, beating out Venice, Italy, the previous record holder by 3 bridges. There are many more bridges in Pittsburgh that are not counted toward the world record as they lack piers.
CURVILINEAR BRIDGE METHOD:
LOCATING BRIDGES BETWEEN STATES
OF OPTIMISM AND PESSIMISM