When is a driver required to drive on the “hard shoulder” - where the “shoulder” is asphalt-paved and free of traffic - in order to allow another vehicle to overtake him?

When a driver of a motor vehicle is forced to drive very slowly due to the freight he’s carrying or to the steepness of the road, and he delays the traffic behind him.

When the vehicle drives very slowely for any reason.

Only when the vehicle is forced to drive slowly on a steep uphill climb, and disturbs the free traffic.

Never. It is prohibited to drive on the “hard shoulders”; hence, a vehicle that delays the traffic behind it should pull into the “hard shoulder” and stop, to allow the traffic congestion behind him to open up.