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Tunnel jacking

Jacked Tunnel, BostonJacked tunnel, Boston Central Artery projectMott MacDonald has gained extensive expertise in this specialist tunnelling technique over the last 20 years. Tunnel jacking was first used in the UK in the 1960’s as a development of pipe jacking, when increased circular pipe sections became too large to easily manoeuvre into thrust pits. The technique has evolved from moderately sized sections, jacked in modules to form bridge abutments, to monolithic rectangular tunnel sections to allow passage of three lane highways beneath railroads, highways, rivers and airport runways. Tunnel jacking often provides the only practical solution to achieving a shallow tunnel beneath a facility without significantly affecting its operation.

We've been involved in all aspects of development and innovation associated with tunnel jacking, undertaking projects from pedestrian subway boxes to multi-stacked jacked units forming bridge abutments and full sized highway jacked tunnel boxes. Often these projects have required tunnel installation beneath major facilities such as multi-track mainline railways, highways and airport runways. Tunnel jacking requires close co-ordination between designers and contractors, including careful monitoring of ground movement effects during installation. Mott MacDonald has also developed instrumentation data collection and reporting tools to enable effective monitoring and control of ground movements to manage risk during construction.

Thrust Pit, BostonThrust pit for ramp D jacked tunnel, Boston Central Artery ProjectMott MacDonald was appointed as the designer for three highway jacked tunnel structures passing beneath mainline tracks at Boston South Station. This work forms part of the $10.8 billion Boston Central Artery Project. The tunnels, at 11m high are up to 24m wide and 115m long, represent one of the largest and complex jacking installations ever undertaken. We are also project manager for the development of a highway tunnel to be jacked beneath the M1 motorway. This will be the first application of the technique of this scale under a major highway in the UK.

Examples of other jacked box projects include:

  • Jacked abutments to Poplars Railway Bridge, UK
  • Fawdon Railway Bridge, Newcastle, UK
  • Jacana Underpass, Melbourne, Australia
  • Sungshan Airport Highway Tunnel, Taiwan

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