Motorists travelling on the Newell Highway near Coonabarabran are being diverted following a two trush crash overnight.
The highway is closed in both directions, just past the Oxley Highway.
Traffic is being diverted to Gunnedah via the Oxley Highway and Kamilaroi Highway.
This diversion is suitable for all vehicles and adds around one hour extra travel time.
Emergency services and traffic crews are on site.