Tunneling the State of the Art: A Review and Evaluation of Current Tunneling Techniques and Costs, With Emphasis on their Application to Urban Rapid-Transit Systems in the U.S.A., Distributed by Clearinghouse, 1968

Subseries 8 contains reports about mass transportation systems in Pittsburgh and other U.S. Cities. Particular reports of interest include those that reference mass transit systems that never came to fruition, including an underground subway system proposed by the Department of City Planning in the 1930s. In the mid-1960s, the Westinghouse Company’s Skybus project was proposed, which was a major mass transit proposal that would have provided continuous service via the Skybus rail.