The Transport Agency is attempting to keep State Highway 8 into the Otago town of Cromwell open overnight, although the slope above the road remains unstable.
The highway, near the intersection with State Highway 8B at the Deadman's Point Bridge, has been reduced to one lane for much of the day due to a slip.
Two helicopter crews have spent hours sluicing and will continue to do so as long as weather and light allows.
The agency says floodlights will be used overnight, and motorists should expect delays.
Slip on the move at Cromwell, Deadmans Point, SH8 down to one lane, possibility of an overnight closure https://t.co/xdrReVfO9J— Waka Kotahi NZ Transport Agency news (@WakaKotahi_news) July 14, 2020
Transport Agency spokesperson Mark Stewart said crews were closely monitoring the potentially significant slip.
Stewart said those travelling between Clyde or Alexandra and Cromwell needed to leave early today to avoid an overnight closure.
The highway, which has no detours, may be closed from 5pm.
The next update is expected tomorrow morning following further geotechnical inspection.