The 15-metre long anchors are placed underneath the road and the 20-metre long sheet piles will stand vertically, back from the river's edge.
The road will remain open for the duration of the works, with a 50km per hour temporary speed limit in place.
Initial works involve site preparation and traffic management, as well as temporary widening of the road outside the Marae, followed by the creation of a platform along the river below the road.
Over summer, anchors will be installed and tested, followed by the installation of sheet piles.
While Waka Kotahi wants to minimise any disturbance to local residents, the works may generate some noise and vibration, the agency said.
Upon completion of the works, the area will be revegetated in association with local iwi.
The works are scheduled to be completed by late March 2021.