Tunnel 21






November 2021



CMT Group was subcontracted to HEB Construction on the re-alignment of the rail line, bypassing the Tar Barrel Tunnel (the oldest on this rail line), for over 1 year. The rail diversion is bypassing the oldest tunnel on the northern line between Christchurch and Blenheim to reduce the train slowing at this point. It will give rail and road a good upgrade that is long overdue.

Our teams of civil construction contractors, qualified drainlayers and digger operators are installing drainage and forming sides to the new diversion.

Civil Construction of Tunnel 21
Civil Construction of Tunnel 21
CMT Group was engaged by the main contractor, HEB Construction, to undertake various civil and drainage works on this project.

Our scope of works included:
Drainage (excavation and installation of new drainage lines and systems for the new rail tunnel being constructed)
Install all sumps, manholes, inspection joints, etc.
Excavate new rail tunnel
Construct all concrete and rock formations on site
Road construction and compaction control
A particular challenge of this job was the high requirement for accuracy, with very little room for error. Safety is also a major concern, as we were working next to an active rail line. Through the careful application of health and safety practices, we have managed to avoid any incidents so far.

One particularly demanding aspect was that we had to install three culverts in a 36-hour period where rail traffic was stopped, working under scrutiny of both HEB and KiwiRail. To ensure that we made this absolute timeline, which could not be moved, we planned our methodology beforehand, so that everyone knew what had to be done every hour. We worked around the clock and delivered all three culverts successfully within the given time.

The large scale of this project serves to provide assurance that CMT Group can successfully deliver complex and demanding civil construction work for KiwiRail.
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