"The only available route is through Paekakariki Hill which is only suitable for cars," Metlink said.
"We have bus replacements operating between Porirua and Plimmerton, however, we are offering no services between Plimmerton and Waikanae at this stage.
"Please find alternative transport if you are travelling north of Plimmerton."
The NZ Transport Agency asks motorists in the area to use Paekakariki Hill Rd as a detour route and said the route is not suitable for heavy vehicles.
The closure is the second time SH1 has been closed near Wellington following an earlier crash at the Mill Rd roundabout near Otaki about 5.30pm, which caused extensive delays.
