Why we did this work
We did this work because structural assessments showed that while the tunnel itself was likely to withstand a reasonably large earthquake, the adjacent hillside and old tunnel entrances could come down and block this important bus route.
The strengthening works reduced the risk to users and made it more likely the tunnel will be able to be used following an earthquake.
This work is part of the Council's ongoing programme to strengthen important transport routes and earthquake-prone structures.
The work included
- strengthening the bus tunnel portals by installing reinforcement structures – four new vertical buttresses on each side of both entrances – incorporating anchors drilled and secured to the hillside
- a new reinforced concrete horizontal beam at the top of each tunnel portal that attaches to the two vertical pillars either side of the portal face
- installation of rock protection: rock anchoring and rock-fall netting in the south-west corner (Hataitai end)
- some repair work to the portal façade, including filling cracks and painting, because the Hataitai bus tunnel is a heritage structure in our District Plan.