Police are investigating a serious single-vehicle truck crash that occurred about 5am this morning on the Tasman Highway between Falmouth and Scamander.

A 54-year-old man from New Norfolk was taken to the Royal Hobart Hospital in a serious condition by helicopter.

The Tasman Highway will remain closed for a number of hours while the truck is righted and towed from the scene.

Road diversions are in place, with traffic being diverted between Scamander and St Marys via Upper Scamander Road, Semmens Road, and German Town Road.

Investigations into the crash are continuing and police would like to speak with anyone who was travelling in the area at the time of the crash.

Anyone with information or dashcam footage is asked to contact St Helens Police on 131 444 or Crime Stoppers Tasmania on 1800 333 000 or at crimestopperstas.com.au. Information can be provided anonymously.