Tunnel Boring Machine Selection for the Baltimore Red Line Downtown Tunnel

摘要

The Baltimore Red Line Project by the Maryland Transit Administration (MTA) involves design and construction of a three mile long tunnel through downtown Baltimore, enabling light rail service between residential and business areas. This paper focuses on the considerations for the selection of an appropriate Tunnel Boring Machine methodology for the Downtown Tunnel contract procurement. Design challenges of tunneling beneath downtown Baltimore include: a tight right-of-way; close proximity to historic and modern high-rise buildings; pre-existing underground tunnels and utilities; and extremely challenging ground conditions consisting of soil and rock in both full-face and mixed-face conditions. A comprehensive assessment and comparison of state-of-the-art tunnel face support, including innovative hybrid machine techniques with earth pressure balance, slurry face control and open-mode capabilities was performed to determine the most suitable approach for the project.