What is a fundamental rule when driving on a dual carriageway?

Driving on a dual carriageway involves specific rules that are designed to ensure safety and facilitate smooth traffic flow. Keeping to the left lane unless overtaking is a fundamental rule because the left lane is generally reserved for regular traffic flow, while the right lane is intended for overtaking slower vehicles. This practice helps to maintain a consistent speed limit across lanes, reduces the likelihood of sudden lane changes, and minimizes the risk of accidents. Additionally, it allows for more efficient movement of vehicles, as faster vehicles can overtake on the right without disrupting the general traffic flow on the left.

Maintaining this lane discipline is crucial for the overall safety of all road users on a dual carriageway. It encourages orderly driving and helps prevent congestion and confusion among drivers.