The Transport Agency says it fears the damage to bridges in the Manawatu Gorge is likely to be serious.
State Highway Three through the gorge has been closed for nine months by a landslip.
The agency says soil has been removed from the slip at the rate of 3000 cubic metres per day and the last debris should be gone within two weeks.
Engineers expect to be able to fully assess bridge damage next week, but they say preliminary checks indicate a possible significant collapse along one section of a bridge at the Woodville end of the slip.
NZTA says it will have a better idea of when the road will be reopened after further inspections.