Is undertaking illegal in the UK?

is undertaking illegal

Undertaking – where a vehicle on an inner lane passes one in an outer lane ‑ is not illegal in the UK, even if it is unwise.

Undertaking on motorways in the UK is NOT punishable by the law. You can happily pass another car while driving to the left of them on a motorway or dual carriageway and if the police spot you, they won’t necessarily fine you. However, it’s not recommended and there are times when it might be dangerous.

What does the Highway Code say about undertaking?

The rule of the road states: “Do not overtake on the left or move to a lane on your left to overtake.” However, it does say that it’s alright to overtake cars in lanes on your right in slow-moving traffic.

Even if that’s the case, you definitely shouldn’t weave in and out of traffic in order to ensure you’re constantly in the fastest moving lane.

Can I undertake a middle lane hogger?

According to Rule 264-269 of the Highway Code which cover overtaking, it states: “Keep in the left lane unless overtaking.” Middle lane hoggers – drivers who sit in the middle lane when the lane to the left is empty ‑ are clearly breaking that rule. Although not strictly illegal, you shouldn’t undertake them. It makes you no better at driving than they are!

But if it’s safer than moving from the left lane into the right lane to go past them before returning to the left lane, you might argue you have a good reason to do it.

is undertaking illegal. image showing busy smart motorway with speed limit at 40mph.
Average speed limits and smart motorways can make undertaking unavoidable

What is the penalty for undertaking in the UK?

Although not strictly against the law, the police might fine you for overtaking on the left. That will come in the shape of a fixed penalty notice for careless driving or driving without due care and attention. It could result in a £100 fine and three points on your licence. Or you may be sent on a driver education course.

In extreme cases, the police might charge you with dangerous driving. This will result in a court summons and can be up to nine points on your licence and a £5,000 fine. The above penalties are most likely for the drivers you see using undertaking as a way of speeding past other cars – as you might in a video game.

Yes, you can undertake on a smart motorway. There are often signs advising drivers to stay in their lane. This is because it can be difficult, dangerous and disruptive to change lanes.

In this case, it’s probably safer to undertake someone who’s travelling more slowly than you.

It’s also perfectly legal to undertake on a dual carriageway where a car might be turning right from the right-hand lane.

If you’re unsure, it’s safest to assume you shouldn’t undertake.

What about average speed limits?

With average speed limits, it’s a similar story to smart motorways. You can undertake a slower car without fear of being pulled.

Very often when there are average speed limits, you can’t help but drive faster than the vehicle(s) in the outer lanes. This is because it can be difficult, dangerous and disruptive to change lanes. And sometimes, in roadworks with average speed checks, there are signs telling you to stay in lane.

Some cars have cruise control and will stay at a constant average speed. This enables them to effectively control the speed of that lane. If another car on an inner lane has its cruise control set at 2mph higher, then traffic in that lane will have little choice than to pass the cars in the outer lane.

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