What we did
- built new retaining walls on the Northland side in front of the two existing retaining (or wing) walls that are on either side of the tunnel entrance
- constructed a new reinforced concrete beam behind the top of both tunnel entrances which will help secure the portal to the underlying rock
- enlarged the two existing vertical buttresses on the Karori side and secured them to the hill with long steel rods called rock anchors
- cleared vegetation and built three new buttresses on the Karori side in front of the existing retaining wall to the right of the tunnel entrance
- drilled and installed 36 rock anchors
- repaired cracks, plastering and repainted the tunnel entrances
- planted the banks above the tunnel.
Background
The tunnel was built in 1927 and is listed as a heritage structure in our District Plan.