A body representing trucking companies fears a section of the main highway into Taranaki from the King Country is on the verge of collapse.
The Road Transport Association says poor drainage on State Highway 3 at Stockman's Hill near Mahoenui has left a 100m portion of road waterlogged, causing sections to break away.
Executive officer Tom Cloke says 700 trucks use the road each day, and he does not want it to collapse like it did in the 1990s.
Mr Cloke says there is only one route in and out of Taranaki, and it is very vulnerable.
The Transport Agency is awaiting an engineering report on the road.
But its state highway manager, Kaye Clark, says she does not believe there is any immediate risk.