The lorry landed upside down and the driver escaped from the wreckage with only bruising and shock after the accident at Skyreburn, about two miles west of the town.
The driver, who has not been named, was treated at the scene for cuts and bruises as well as shock but was not hospitalised.
Police Scotland has warned of delays and says there is slow traffic in both directions with the road partially blocked.
A spokesman said: “Work is going on at the scene but the vehicle has had to be made safe before work can start.
“The driver has had a lucky escape by all reports and suffered only minor injuries.”
No other vehicle was involved in the accident which happened just before 10am.
