One lane of State Highway 4/Anzac Parade in Whanganui remains closed after last week's slip near Georgetti Rd.
Waka Kotahi/NZ Transport Agency says it is considering its options for the highway, including moving the road itself.
The majority of the debris blocking the road was cleared after the slip which occurred on Easter Monday, but that section of the busy route remains with one lane under traffic light control.
Waka Kotahi/NZTA could not provide a timeframe on how long the road would be reduced to one lane and said work to find a solution was ongoing.
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"We are continuing to explore a long-term solution for the Anzac Parade site. Options we are considering include retaining the hillside, which would involve further discussions with the property owner, and moving the road away from the hill," a spokesperson said.
"We will have a better idea about timeframes once we're able to decide on a preferred option. In the meantime, the road will remain down to one lane for safety."