Authors:
D. Watson, J. Davies, J. Doyle
North American Tunneling Conference 2010 (NAT 2010), June 2010
Abstract
This paper describes the key planning phase issues and tradeoffs associated with a potential tunneled portion of the proposed Urban Ring Project in Boston, Massachusetts. The project is intended to provide new and improved transit service along an orbital corridor in Boston and several surrounding municipalities linking up the existing radial transportation system outside the downtown core with a Bus Rapid Transit system. The tunnel portion of the corridor would be approximately 1.5 mi in length and would be constructed under the densely developed Longwood Medical and Academic area (LMA) and Fenway neighborhood of Boston. The dense urban environment coupled with highly sensitive surface and subsurface conditions imposed many constraints on the planning and conceptual design. Consequently, a wide range of alignments and profiles were considered along with different tunnel construction techniques including: single bore or twin bore pressurized face tunnel boring machines up to 42.0 ft in diameter; sequential excavation methods; and cut and cover techniques.
