Utilization of space above CA/T tunnel in downtown Boston

This paper presents broad spectrum of considerations in the planning and design phases for utilization of space above the CA/T tunnel. The issues include land planning and zoning, utilities, traffic management, structural design, geo-technical features and environmental commitments. Specifically this paper focuses on the structural design considerations and other details for the deepest section of CA/T which begins at Kneeland Street and ends at Congress Street. This section of CA/T tunnel supports the MBTA’s South Boston Pier Transitway tunnel for electrically operated buses. The Transitway tunnel crosses the Red Line subway at the South Station, thus forming three tier tunnels at Summer Street intersection.