NATM and Ground Freezing combined at Russia Wharf

Boston’s Silverline may be the way new urban transportation systems will develop in the years ahead. It combines dedicated surface bus lanes together with undergound bus tunnels and limited stops with the flexibility of special rubber tyred articulated buses, driven by low pollution fuel systems (compressed natural gas) on the surface sections transferring to ‘no-pollution’ electric power in the tunnel sections. The construction of one of the Silverline tunnel sections, where the underground busway has to pass only a short distance under 100 year old buildings which are in constant use, has necessitated an interesting construction technique involving NATM in conjunction with ground freezing and spiling.