ABSTRACT
The City Rail Link (CRL) in Auckland, New Zealand is the largest transport infrastructure project ever to be undertaken in New Zealand with a project cost of up to NZ$5.5B. The CRL is a 3.45 km twin-tunnel underground rail tunnel underneath Auckland’s city centre, between Waitematā Station (Britomart) and Maungawhau Station to better connect the Auckland rail network. The 3.2 km bored tunnels were constructed using an earth pressure balance Tunnel Boring Machine (TBM).
The CRL project is characterized by geometric, environmental and geological challenges due to its designation boundaries and project setting. Tunnelling in this setting required due consideration of geometrical restraints, ground conditions and sensitive receivers. This paper describes the lessons learned from the novel features of precast concrete segmental lining design and construction to achieve a high quality permanent segmental lining. The key challenges of design and construction of precast concrete segmental lining include tight alignment curves down to 141 m radius, adopting two different segment lengths, crossing under a major motorway junction, ram pad configuration, as built lining details, tolerances, tunnel construction and performance. Practical aspects of trapezoidal universal segment configuration, hybrid segments, guiding rod longitudinal joints and gaskets are also discussed.
