LYTTELTON TUNNEL DRIPSHIELDS

The Lyttelton tunnel is the oldest operational tunnel in New Zealand, with a length of 2.6km, most of which is unlined. It has always had water egress, but the scale of egression increased following the Christchurch earthquake sequence. The water was causing corrosion to the rail head and degrading the sleepers prematurely.

Rock Control were engaged early in this project to discuss options of how to divert the water away from the rail head and sleepers, any solution required a 100 year design life. The design chosen was Kwila batons installed to the tunnel roof with plastic sheeting fixed to the batons.

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Accessing the work area was done by use of a KiwiRail HRV with a certified scaffold attached to the deck, this gave us a large work platform so we could efficiently install batons and sheets with a crew of up to four people. Clearances were carefully checked during installation and work planned so that nothing was left “half done” so that the rail operations could commence immediately after each shift. We worked collaboratively with KiwiRail on this project, KiwiRail provided the site protection, HRV’s, and driver which let us concentrate on installation.