Rule 166 ↗
DO NOT overtake if there is any doubt, or where you cannot see far enough ahead to be sure it is safe. For example, when you are approaching
a corner or bend
a hump bridge
the brow of a hill.
Safety First : The Golden Rule of Overtaking
Last updated:
📜 Highway Code Regulation
🚘 Independent revision guide
🌐 Multi-Language Translation Support
📖 Rule 166 Full Regulations & Explanation
Text shown in the rule image
Safety First : The Golden Rule of Overtaking
The Core Mandate
The " If in Doubt " Rule
Rule 166 explicitly states : DO NOT overtake if there is any doubt about the safety of the maneuver .
The Visibility Standard
You must be able to see far enough ahead to be 100 % sure the path is clear before attempting to pass another vehicle .
Hazardous " Blind " Zones
Hump Bridges
The steep incline and sudden drop of a hump bridge create a vertical blind spot that masks traffic on the opposite side .
Corners or Bends
Curved roads restrict your line of sight , hiding oncoming vehicles until they are directly in your path .
Brow of a Hill
Approaching the top of a hill prevents you from seeing what is descending on the other side , making it a prohibited zone for overtaking .