A police officer has clarified the only rare circumstances in which undertaking is permitted on roads, warning that it is generally dangerous and discouraged.
Sergeant explains when undertaking is allowed
Sergeant Owen Messenger from Devon and Cornwall Police’s Roads Policing Unit highlighted when undertaking can be permissible – and it isn’t often. He explained: “You can’t undertake on the motorway. The only time you can undertake is when your lane is genuinely moving more slowly than the other lanes. That’s generally when you’re going through roadworks, or it’s heavy traffic, or something like that.”
He added that it’s discouraged because “people aren’t expecting you” – and as drivers often move back to the left lane, their “default position on the motorway”, it can lead to serious crashes. Rounding off the video, he urged motorists: “Please don’t undertake on the motorway, it’s really really dangerous.”
What the Highway Code says
The Highway Code is clear that overtaking should usually be done on the right, and that passing on the left isn’t recommended in normal, free-flowing traffic. However, Rule 268 provides exceptions for slow-moving queues: motorists may pass slower vehicles on either side, depending on how traffic is flowing, provided they stay in their lane and don’t weave in and out.
The same rule also reminds drivers to keep left unless they’re overtaking – and ignoring that advice can be extremely dangerous. If you suddenly appear on another driver’s left, they may not expect you to be there, leaving them less time and space to react if they drift or change lanes. At motorway speeds, even a small mistake can have serious consequences.
Ultimately, patience and safe driving protect you – and everyone else on the road.
