The A1 southbound between Junction 47 and 48 near Knaresborough has now re-opened.
The road closed shortly after 6.25am due to an incident involving a single vehicle.
Officers are appealing for anyone who saw a Black VW estate car with hazard lights on and was stationary, on the southbound carriageway between 5am and 6.30am, to come forward. Officers also request that anyone with any dashcam footage from the area at that time gets in touch.
Dial 101, press 2 and ask for Traffic Constable 174 David Minto. Alternatively you can email David.firstname.lastname@example.org
Please use reference number 12210091937 when passing on any information.