What is undertaking and is it illegal UK?

What is undertaking?

Undertaking is the act in which a motorist passes a slower moving vehicle on its left-hand side (kerb side). Unfortunately, this is a common occurrence on roads with multiple lanes such as motorways. Undertaking is a dangerous practice which could increase the chances of a road accident. By law motorists should use right lanes to overtake slower vehicles, therefore undertaking on the left is unexpected and could result in multiple vehicles moving into the same gap at the same time.

Is undertaking illegal UK?

In the Highway Code, undertaking is strongly discouraged. It says, “Do not overtake on the left or move to a lane on your left to overtake.” That said, strictly speaking, undertaking is not illegal in the UK.

Also, rule 268 of the Highway Code, states,

“In congested conditions, where adjacent lanes of traffic are moving at similar speeds, traffic in left-hand lanes may sometimes be moving faster than traffic to the right. 

In these conditions you may keep up with the traffic in your lane even if this means passing traffic in the lane to your right. 

Do not weave in and out of lanes to overtake.”

This suggests undertaking is acceptable in congested conditions if your lane is moving faster than a lane on the right.

Is undertaking acceptable in any circumstances?

Although undertaking should be avoided where possible, there are some circumstances where it’s classed as acceptable to undertake. These are:

• Where average speed checks are in operation.
• If the vehicle in front of yours is turning right or U-turning, it is acceptable to undertake on the left. Of course, you need to ensure there’s enough space to safely undertake, otherwise it’s best to wait until the other vehicle moves.

Why do some drivers undertake?

As undertaking can be a dangerous act, it’s difficult to understand why so many drivers would undertake. However, several main reasons have been highlighted for this. These include:

• Particularly on motorways, motorists may become frustrated by middle-lane hogging and try to ‘prove a point’ by undertaking them.
• Some motorists do not understand what undertaking is and lane discipline on multi-lane roads.

Can cyclists undertake?

It isn't illegal for cyclists to undertake other vehicles; however, they should be cautious when doing so. Known as filtering, it’s common for cyclists to undertake and overtake other vehicles as a way to make faster progress. That said, ideally cyclists are advised to only filter traffic when the other vehicles are stationary such as waiting at a red light. Also, cyclists are advised against undertaking long vehicles like HGVs. Drivers of long vehicles are more likely to miss seeing you undertake, and this could result in a road accident.

In order to drive safely, all drivers should avoid undertaking another vehicle, where possible. Whether you’re driving on the motorway or in built-up areas, drivers should follow rule 267 of the Highway Code and “Overtake only on the right”. Always take care when overtaking, particularly at night or when visibility is poor. If you’ve found this GB Vehicle Leasing article interesting, visit our Facebook page for more tips and motoring advice. Also, view our related article - What is brake checking?