The zip merging debate: is it perfect sense or pushing in? We find out

zip merging

Are you driving in the closed lane on the left, or queuing patiently on the right? (Picture © Alamy)

The debate on how you merge into moving traffic when the lane you’re driving in closes is a fierce one. Do you stay in the closing lane to the very end, then merge in turn with the traffic in the open lane? Or do you move out of the closing lane as soon as you possibly can?

It’s a bit like whether you put cream on a scone before the jam or vice versa. Or perhaps even more fundamentally, whether you pronounce the word scone like ‘own’ or the other way. The law states that we should merge in turn, better known as zip merging. Yet only around a quarter of drivers (27 per cent) know this is the correct thing to do. Read on to find out why people who stay in the closing lane aren’t doing anything wrong.

What usually happens

You’re on a dual carriageway or motorway and you see signs warning that a lane is closing. Most of us – seven out of 10 according to a survey by Halfords – believe we should get into the lane that is staying open as quickly as we possibly can. This can result in hundreds of metres of perfectly usable carriageway lying empty. On top of that, 3 per cent of drivers actually think it’s OK to spread their car over two lanes to stop anyone else using the empty lane. That’s nearly three quarters of drivers (73 per cent) who’re wrong.

What the Highway Code says

Rule 134 of our road legislation states: “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.”

What does that mean in practice?

If you’re in the lane that’s closing, stay there. Drive in it for as long as you can, then flick on your turn indicator and when it’s safe to do so, merge with the traffic in the open lane. Ideally, each driver in the open lane should let one driver from the closing lane in.

zip merging

Do you know what to do if you see one of these?

Why don’t we do this?

If the law states merging in turn is what we should do, why don’t we do it? Candace Gerlach from Green Flag believes it could be down to our nationality. “As Brits, queuing is in our culture,” she says.

“We like to queue and we’ve been brought up to think that being polite is the way forwards. That’s great but it doesn’t mean we should abandon the lane that’s closing immediately. And it doesn’t mean that anyone who’s making use of that lane is being rude. Britain is a small country with relatively crowded roads and we need to make use of as much of any open carriageways as possible. Merging in turn when it’s safe to do so enables us to do exactly that.”

What’s the science behind it?

Traffic engineer Ken Johnson from Minnesota in the US has conducted research into the pros and cons of zip merging. He discovered three main benefits:

  1. With two full lanes of traffic, the speed differential between lanes is reduced. With all traffic travelling at roughly the same speed, making the move from closing to open lanes is easier and safer.
  2. As all the available road is being used, the length of the queue is reduced by up to a half (40 per cent is common, according to Johnson.)
  3. With both lanes moving slowly and at similar speeds, everyone is disadvantaged. Drivers may not be happy that they’re in a jam but they can see everyone is in the same boat. The result? They don’t get as angry with other drivers, reducing the number of road rage incidents.

It’s not a perfect scenario but it’s making the best of a bad job and crucially, people moving in from the closing lane aren’t delaying people in the open lane or stealing any secret benefit. Ken Johnson explains: “Our analysis has shown that the zipper system has no effect on travel time. And it produces a much safer merge situation, making the length of the overall queue much shorter.”

There you have it: zip merging doesn’t penalise anyone. As Candace Gerlach claims: “We are saying: ‘come on guys, let’s start a movement’. We want to try to change people’s behaviour to embrace zip merging rather than frown upon it.”

7 comments on “The zip merging debate: is it perfect sense or pushing in? We find out

  1. Vernon February 19, 2019 8:20 am

    Very sensible. It’s as it should be. Why so many drivers are so aggressive, racing around in a hurry getting nowhere, I will never understand. They should learn to ZIP IT.

  2. Eric Hayman February 19, 2019 9:38 am

    Merge in turn is common sense. It is not “pushing in”. It is lazy drivers who cannot be bothered to pay full attention to driving who think of it as pushing in. Currently on the A338 coming off the A31 and towards Bournemouth, Lane One is in use only for Christchurch and the airport. Lane Two only for Bournemouth. The Bournemouth lane is much more heavily used, but long before the signs indicating which lane to use, Lane One is empty. So the occasional driver overtakes the Lane Two vehicles and then needs to get into Lane Two. Is that driver wrong? I would say no.

    • Momfer Undersand February 25, 2019 7:12 pm

      It is “pushing in” when the the driver wanting to join, Indicates one blink and whacks it in there assuming I’ll brake for him. And then goes absolutely nuclear because he wasn’t let in.
      Indicate and wait for the space, I’m more then patient enough to give space.

      • Eric Hayman February 26, 2019 4:12 pm

        On the road I have mentioned, the A338 – known as the Spur Road, where traffic joins the normally two lanes each way dual carriageway at the airport/Christchurch junction – you get the ‘push in” drivers, noticeably when going home in the afternoon, and too impatient to wait to be let in across the entry slip give way line. But this is not the merge in turn the original article was about; just one of countless junctions where traffic joins a major road.

  3. Ray Stevens February 19, 2019 9:19 pm

    anyone driving in the closed lane is potentially putting other vehicles drivers and passengers in danger, its closed for a reason, possible emergency vehicles may get stuck in trying to get to a hazard, by continuing on up the closed lane all they are doing is jumping to the front at best, worst of all flaming annoying to other road users, especially me….Europe when they close a lane everyone gets out of that lane early as possible end result is traffic moves more freely less potential for further dangers ensuing ….and if you are caught Not getting out of the closed lane potential for a heavy fine payment on the spot….. they should fine these drivers over here in the UK

    • Eric Hayman February 20, 2019 11:53 am

      What closed lane? I was describing two open lanes, one eventually going to the left, one straight on. Only on nearing the divergence are there any signs to say which lane to take. It has nothing to do with blocking emergency vehicles. The only time I see UK drivers using closed lanes is on motorways, when the very clear red X is ignored. And on motorways when drivers are told by the matrix signs to merge, they are seen ignorantly using one lane only. By the way, the UK is part of Europe,

  4. Eric Hayman February 21, 2019 3:10 pm

    Thank you, John. I was simply giving an example of where lane changing is required because of what the local council is doing in connection with a new road scheme. Because Lane Two is much more heavily used than Lane One, it is inevitable that most of the movement will be into Lane Two. And not until the first warning sign is there any indication that each of the two lanes of the southbound carriageway will lead to a different destination.. “Merge in turn” is an official sign, used countrywide. What is the problem? Do non-mergers also disobey other road signs? Merging makes the best use of road space, and reduces long tailbacks. All it requires is politeness from the Great British Public.

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