Merge in turn — Rule 134, lane closures and joining a motorway

Two lanes, one closing, a mile of cones ahead — and two camps of drivers who each think the other is in the wrong. One queues in the open lane from the first sign. The other drives to the merge point and slots in. The Highway Code settles it in a single sentence, and the reason the argument never dies is that both camps are right, just about different roads. Rule 134 is the rule; Rules 288, 151, 268 and 259 fill in the corners.

You should follow the signs and road markings and get into the lane as directed. In congested road conditions do not change lanes unnecessarily. Merging in turn is recommended but only if safe and appropriate when vehicles are travelling at a very low speed, e.g. when approaching road works or a road traffic incident. It is not recommended at high speed.

Rule 134 is three instructions, not one

Read it as a list and the confusion disappears.

1. Follow the signs and road markings and get into the lane as directed. Where the lane allocation is signed or painted, the signs win. Nothing below overrides this.
2. In congested road conditions, do not change lanes unnecessarily. Hopping between lanes to gain two car lengths is what the Code tells you not to do.
3. Merging in turn is recommended — but only when vehicles are travelling at a very low speed, and the Code gives two examples: approaching road works, or a road traffic incident. It is not recommended at high speed.

That last clause is the whole argument. Merge in turn is a low-speed technique for a queue, not a licence to run the closing lane at speed and cut in at the cones.

Note the verb: Rule 134 says merging in turn is recommended. There is no MUST anywhere in it, and the Code is explicit about what that means.

Although failure to comply with the other rules of the Code will not, in itself, cause a person to be prosecuted, The Highway Code may be used in evidence in any court proceedings under the Traffic Acts (see The road user and the law) to establish liability. This includes rules which use advisory wording such as ‘should/should not’ or ‘do/do not’.

So failing to zip-merge is not in itself an offence, and neither is joining the open lane at the first sign. Advisory rules still carry weight — they can be used in evidence to establish liability — but nobody in that queue is committing a crime by choosing a lane.

Which behaviour the Code backs, situation by situation

Road works: Rule 288 backs the zip merge — and bans the run-up

The road works rule says both halves of this out loud, in the same list of bullets.

Where lanes are restricted due to road works, merge in turn (see Rule 134).

Do not switch lanes to overtake queuing traffic.

The two are only in tension if you read the second one as banning the closing lane. It does not. The distinction the Code is drawing is between staying and switching:

• You are already in the lane that closes, you stay in it, and you merge at the front. That is merging in turn.
• You are in the open lane, you pull out into the closing lane to get past the queue, then push back in. That is switching lanes to overtake queuing traffic, and Rule 288 tells you not to.

Rule 288 also carries the instructions that make the merge work at all: you MUST NOT exceed any temporary maximum speed limit, keep a safe distance from the vehicle in front, get into the correct lane for your vehicle in good time and as signs direct, and do not drive through an area marked off by traffic cones.

Slow-moving traffic: Rule 151 and the “undertaking” objection

Two rules do the work here, and neither says what the objection assumes.

Rule 151, headed “In slow-moving traffic”, lists what you should do in a crawling queue. One bullet is the one people reach for:

not change lanes to the left to overtake

It targets the lane change, not the position. If a queue in the right-hand lane is barely moving and your own lane is moving faster, you have not undertaken anyone by staying where you are.

Rule 268 says the same thing for motorways in plain terms: “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.” It closes with the limit that matters: “Do not weave in and out of lanes to overtake.”

So the answer to “isn’t using the closing lane just undertaking?” is no on two counts — you are not changing lanes to do it, and on a motorway the Code expressly permits passing traffic in the lane to your right in congested conditions.

Blocking the closing lane is not enforcement

Nothing in the Highway Code appoints a driver to police the queue by straddling both lanes or sitting alongside to stop others passing. Rule 147 asks the opposite of everyone involved: be careful of and considerate towards all types of road users, try to be understanding if other road users cause problems, and be patient — anyone can make a mistake.

Rule 133 sets the standard for the merge itself, from either side of it:

If you need to change lane, first use your mirrors and if necessary take a quick sideways glance to make sure you will not force another road user to change course or speed. When it is safe to do so, signal to indicate your intentions to other road users and when clear, move over.

“Will not force another road user to change course or speed” is the test, and it cuts both ways: it is breached by the driver who dives into a gap that is not there, and by the driver who swerves across to shut one. Driving without reasonable consideration for other persons using the road is a criminal offence under section 3 of the Road Traffic Act 1988 — our guide to lesser-known driving offences sets out the penalty that attaches to it.

Joining a motorway is a different rule entirely

Merge in turn does not apply on a slip road, and this is where the second recurring argument starts — the one about whether drivers in lane 1 are supposed to brake for joining traffic. Rule 259 puts the duty on the joining driver.

When you join the motorway you will normally approach it from a road on the left (a slip road) or from an adjoining motorway. You should give priority to traffic already on the motorway.

Four things follow from that.

• Priority sits with the carriageway. Traffic already on the motorway does not have to make room, and the Code never asks it to brake for a slip road.
• Match the flow, don’t aim for a number. The instruction is to match your speed to fit safely into the traffic in the left-hand lane. If lane 1 is doing 50 mph in heavy traffic, joining at 70 mph is wrong, not diligent.
• Where the slip road continues as an extra lane, stay in it. No merge is required at all.
• Do not cross the solid white lines that separate the slip road from the carriageway, and do not use the hard shoulder to gain a run-up.

A driver already in lane 1 who moves into lane 2 to leave space is making a lane change, so Rule 133 governs it — mirrors, blind spot, signal, and only when it forces nobody to change course or speed. It is a courtesy, not a duty the Code imposes — and Rule 264 still asks you to keep in the left lane unless you are overtaking.

Some slip roads spell the priority out on a sign rather than leaving it to Rule 259, and the signs that do keep priority with the main carriageway or set the order between the two lanes of the slip road itself. The information sign reading “Additional traffic joining from left ahead. Traffic on main carriageway has priority over joining traffic from right hand lane of slip road” and its counterpart, “Traffic in right hand lane of slip road joining the main carriageway has priority over left hand lane”, both appear in the official sign catalogue — see road signs. Where a sign like that is present, the sign decides, exactly as the first line of Rule 134 requires. The warning sign for “Traffic merging from left ahead” is in the same catalogue, and it is a warning that a merge is coming — not a statement about who gives way.

Learners should know these rules even though most will not practise them: motorways MUST NOT be used by provisional car licence holders unless they are accompanied by a DVSA Approved Driving Instructor in a dual-controlled car displaying red L plates (or D plates in Wales).

Common test questions and the answers

“Two lanes of traffic are merging into one at road works. What should you do?”

Merge in turn — but the answer only holds because the traffic is slow. Rule 134 recommends merging in turn when vehicles are travelling at very low speed, and names approaching road works as its example. Rule 288 repeats the instruction for road works and cross-refers to Rule 134.

“Is it illegal not to merge in turn?”

No. Rule 134 says merging in turn is recommended, which makes it advice rather than a legal requirement. What can bite is how you merge, not whether you did: forcing another road user to change course or speed breaches Rule 133, and driving without reasonable consideration is an offence under section 3 of the Road Traffic Act 1988.

“You are joining a motorway from a slip road. Who has priority?”

Traffic already on the motorway. Rule 259 tells you to give priority to it and to match your speed to fit safely into the flow in the left-hand lane.

“Traffic in your lane is moving faster than the queue in the lane to your right. Can you keep going?”

On a motorway in congested conditions, yes. Rule 268 permits you to keep up with the traffic in your lane even if that means passing traffic to your right. What you must not do is weave in and out of lanes to overtake, or, in slow-moving traffic generally, change lanes to the left to overtake (Rule 151).

“The lane you are in closes in 400 metres and the queue in the other lane is stationary. Do you have to pull in now?”

Only if signs or markings direct you into that lane. Otherwise Rule 134 supports staying in your lane to the merge point and merging in turn at low speed. Do not use the closed area beyond the cones to go any further.

Where this shows up in revision

Merging, lane discipline and motorway joining sit across the Rules of the road and Motorway rules revision topics, and the Highway Code is the first source DVSA names for revising the multiple-choice section. Work the 14 DVSA topics, read Rules 133, 134, 151, 259, 264, 267, 268 and 288 in the Highway Code, and sit a full mock theory test under the real timer. It is free to get started.

Sources

• GOV.UK — Highway Code: general rules, techniques and advice for all drivers and riders (Rules 133, 134, 147, 151)
• GOV.UK — Highway Code: road works, level crossings and tramways (Rule 288)
• GOV.UK — Highway Code: motorways (Rules 253, 259, 264, 267, 268)
• GOV.UK — Highway Code: introduction — wording of The Highway Code, MUST vs should
• GOV.UK — Highway Code: traffic signs — merging and slip-road priority signs
• legislation.gov.uk — Road Traffic Act 1988, section 3 (careless, and inconsiderate, driving)
• GOV.UK — Theory test: revision and practice

Highway Code excerpts are reproduced under the Open Government Licence v3.0.