Introduction
HB Tunnelling was engaged as part of the A4010 Risborough Road works in Aylesbury, a key element of the wider High Speed Two (HS2) programme. Working under principal contractor EKFB and subcontractor OCU, our goal was to deliver critical enabling works to support a Thames Water diversion. The scope included constructing a 5.5m x 5.3m launch pit and a 4m x 4m reception pit, each 6m deep, to facilitate trenchless guided auger boring and pipe jacking. This approach enabled new utilities to be installed safely beneath existing infrastructure, meeting HS2 standards while minimising disruption and maximising efficiency.
Augerboring Front Steer
Objective
The Risborough Road utility diversion required the installation of new pipe beneath a temporary bridge abutment without compromising HS2 programme requirements. Trial holes were undertaken to assess the stiff clay ground conditions and identify the most cost-effective, least disruptive installation technique. Following detailed assessment, including borehole investigations, it was agreed that guided auger boring and pipe jacking would provide the best balance of cost efficiency, accuracy, and minimal disruption.
The operation was planned to take ten weeks using a Bohrtec BM400 LS rig. Two sheet-piled shafts, a launch pit and a reception pit, situated approximately 80m apart on either side of the bridge were constructed using the push-and-dig method, both shafts were fully braced.
The Challenge
From these shafts, two tunnels were augured. Both drives were 600mm in diameter and 78m in length, with concrete pipes jacked into position.
The project was successfully completed on time and within budget and even a mock emergency rescue was carried out in record time. Throughout the works, HB Tunnelling met all HS2 quality, safety and environmental standards while minimising disruption to the local community and protecting existing infrastructure.
“This was quite a challenging project & HB Tunnelling whom we have worked with numerous times before in the past were as usual extremely helpful and efficient in the design and build process. They were very professional & well organised and we will definitely be looking at using this type of innovative trenchless technology on schemes in the future.”
- Caldwell Construction
For any trenchless installation enquiries, please contact a member of the HBT team 0845 388 3325.
