Jacked Box Tunneling Method

Technical manual on the process from the U.S. Department of Transportation.  From the manual:

"Jacked box tunneling is a unique tunneling method for constructing shallow rectangular road tunnels beneath critical facilities such as operating railways, major highways and airport runways without disruption of the services provided by those surface facilities or having to relocate them temporarily to accommodate open excavations for cut and cover construction (Chapter 5). Originally developed from pipe jacking technology, jacked box tunneling is generally used in soft ground at shallow depths and for relatively short lengths of tunnel, where TBM mining would not be economical or cut-and-cover methods would be too disruptive to overlying surface activities.

Jacked box tunneling has mostly been used outside of United States (Taylor et al, 1998) until it was successfully applied to the construction of three short tunnels beneath a network of rail tracks at South Station in downtown Boston . These tunnels were completed and opened in 2003 as a part of the extension of Interstate I-90 for the Central Artery/Tunnel (CA/T) Project. Figure 12-1 shows the opening ceremony for the completed I-90 tunnels. Since CA/T Project represents the most significant application to date of the jacked box tunneling in the US, it will be used to demonstrate the method throughout this Chapter."