Truck drivers had been asked not to use the road and were instead asked to detour via SH12/SH14 through Dargaville.
A police spokesperson said they were anecdotally aware of heavy vehicles using the Cove Rd/Mangawhai detour despite previous warnings.
“Police continue to strongly urge heavy vehicles to avoid using Cove Road,” they said.
“This route is not suitable for heavy vehicles, and continued use will contribute to further damage and delays. For the safety of all road users, please use an alternative route.”
Waka Kotahi advised of delays on the route and advised people to delay their journey or consider travelling via SH12/14.