The Parapara (SH4) between Whanganui and Raetihi has reopened following the installation of roadside barriers at a high risk slip site two kilometres south of Fields Track.
It opened at 4pm on Wednesday.
NZTA Regional Transport Systems Manager Ross I'Anson said travel would be restricted to a single lane at the site while work was undertaken to remove unstable material above the road.
Stop-go traffic controls will in place.
The unstable material was identified during a regularly scheduled geotechnical inspection earlier this week and the road has been closed since 5pm on Monday while a more detailed inspection has been undertaken to determine how to safely remove the material.
