From pedestrian subway boxes to multi-stacked jacked units forming bridge abutments and full sized highway jacked tunnel boxes – we’ve been involved in all aspects of tunnel jacking development and innovation.

Two concrete box structures slid into position form a rail underpass at Shortlands Junction on the UK’s Channel Tunnel Rail Link Often projects call for 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 developed instrumentation data collection and reporting tools to enable effective monitoring and control of ground movements to manage risk during construction.

Today jacked tunnelling is increasingly being used to form grade separated crossings for new highways under existing railways. Its major advantage is that railway services can be maintained while tunnel installation proceeds beneath.

Taipei’s Sungshan airport jacked tunnel passes through soft alluvial material under the runway We have extensive knowledge of the various jacking techniques appropriate for installing tunnels at a range of depths in different ground conditions. Special attention has to be given to ground treatment, application of jacking forces and control of the tunnel face along with vertical and lateral movement.

Mott MacDonald provided specialist construction advice and supervision on the Boston Central Artery jacked tunnels project in the USA – the largest and most complex of its kind in the world. The project involved jacking three full-size interstate highway tunnels, the largest well over 100m long each with sections weighing up to 30 000 tonnes, under an operating commuter railway in downtown Boston.

Our portfolio of jacked tunnels includes:

• Boston Central Artery highway tunnels (Contract 9A), USA
• Jacana Underpass highway tunnel, Australia
• A406 Stonebridge Park road tunnel, UK
• Newcastle Western Bypass highway tunnel, UK
• Jakarta Underpass highway tunnel, Indonesia
• Sungshan Airport highway tunnel, Taiwan
• Shortlands Junction, Channel Tunnel Rail Link, UK

We’ve been involved in all aspects of development and innovation in this special tunnelling technique – from scheme design, detailed design and design reviews to site supervision.