The Johnsonville line cuts up through the Ngaio gorge through 5 tunnels. Over the past 15 years, Abseil Access has helped Kiwirail reduce rockfall on various sections of the line and over the tunnel portals.
In 2019 AA conducted the 6th such project, installing active mesh and anchors between tunnels 1 & 2. The netting was installed first to reduce the chances of rockfall during the drilling phase. The team then use an A-frame drill rig to drill and install 32mm and 25mm diameter GRP anchors.