The northbound lanes of the Waikato Expressway and State Highway 57 near Palmerston North have reopened following separate crashes.
A truck crashed into railings on the Waikato Expressway near Mangaharakeke Rd shortly after 10am, blocking the expressway's northbound lanes.
The truck was towed and the road has since reopened.
Three people were injured on SH57 south of Palmerston North in a serious crash involving two cars about 10.40am.
Police said they were all taken to hospital in a moderate condition.
The cause of the crash was being investigated.