Tinui Slip Road Realignment
Masterton District Council
Masterton, New Zealand
The Masterton – Castlepoint road is the only route connecting Masterton to the Castlepoint Beach tourist destination. It’s also a strategic route providing access for the transportation of logs and stock to State Highway 2. The site, located near the Tinui Village, had suffered continual incremental slumps for many years with the slumps being re-filled following each event. This approach had been effective until a significant slump in 2008 raised the need for a long-term solution.
Calibre first developed a temporary option to keep the road open while geotechnical investigations and a topographical survey determined the cause of the slump. Our team then recommended a long-term solution, which involved a drainage layer and associated system to efficiently dispose ground and surface water prior to placing imported fill and reconstructing the road.
During the detailed design phase a key challenge was to balance horizontal and vertical alignments to minimise earthwork quantities, minimise trimming of existing batters and reduce encroachment into private land. A key challenge throughout the construction period was to maintain safe accessibility for tourist, logging and stock traffic.