At 10.04am on Friday (November 3), Northumbria Police received a report of an injured driver on the southbound carriageway of the A1 at Fawdon.
A police spokesman said: "It is understood that a metal object has fallen from a moving vehicle which has then gone through the windscreen of a van also travelling southbound."
The 61-year-old driver of the silver Citroen Berlingo was taken to hospital with serious head injuries.
One lane of the southbound carriageway was blocked for around one hour while the vehicle was recovered.
Police are now urging anyone who saw what happened in the moments leading up to the collision, particularly passing vehicles with any dash-cam footage, to get in touch so they can determine what has happened.
Officers would also like to speak to drivers of any vehicles carrying metal in the area at the time.
Anyone with information which could assist the investigation is asked to contact police on 101 quoting reference 259 02/11/18 or email the officer in charge at: [email protected]