Damage to the road surface, a foreign object and a malfunctioning car are considered obstacles, but a car stopped because of a traffic jam is not.
Under the definitions in the Rules (clause 3), an obstacle is a stationary object in a lane that prevents you from continuing to drive, for example a malfunctioning car, damage to the road or a foreign object. A working vehicle stopped because of a traffic jam, unlike a damaged or malfunctioning one, will move off again with the flow, so it is not an obstacle.
Option 1. Damage to the road surface physically hinders traffic and is clearly defined as an obstacle.
Option 2. A foreign object on the roadway blocks the road and is classed as an obstacle.
Option 3. A malfunctioning or immobile vehicle blocks the lane and fits the definition of an obstacle.