If you drive a truck with a gross vehicle weight of over 3 t, what's the maximum speed at which you can drive on a motorway?

The D-9 "motorway" signs visible in the picture indicate the type of road on which you are travelling. In accordance with the Road Traffic Law, the maximum permitted speed for a heavy goods vehicle with a maximum authorised mass exceeding 3.5 tonnes on a motorway is 80 km/h.