The main problem with zipper merges in practice are selfish people who rush to zipper and cause even more congestion because of their erratic attempt to merge. Like traffic circles they work great when everyone is doing it right and they cam get really messed up when people do it wrong.
It would be great if zipper merging was taught as part of getting a license. Or they actually required someone to learn how to zipper merge as part of their license renewal.
Do you mean “rush to zipper” as in “using an open lane to move forward and then zipper merge into the remaining lane when that one closes?” That is precisely what you should do.
The problem is the selfish people who refuse to let those people actually zipper merge, like OP.
@Nougat
It’s hard to discuss zipper merging because people use to justify all sorts of dick behavior. Zipping through an empty left turn only lane to skip to the head of a right turn only lane for example. That’s not an example of zipper merging but there’s tons of people who I’ve seen argue that’s acceptable behavior.
The issue is, at the end of the day, that nobody ever seems to know how to keep a decent distance away from the car in front of them. It doesn’t matter how slow traffic is, leave some space in front of you. It gives you room to slow down in case something happens, and it gives everyone else room to merge.
Zipper merging requires matching speed with the lane you are merging into so that drivers can make gradual changes in speed to make an opening for the person merging. That avoids sending a wave of brake slams that results from sudden unexpected lane changes. If you’re passing a bunch of people, you’re probably not doing a zipper merge.
You’re also much less likely to end up with someone not letting you over if they see you matching speed instead of speeding up to the merge point.
If you’re passing a bunch of people, you are using the open lane to travel. By the time the lane you are in comes to an end, you then modulate your speed to match traffic in the slower lane, and merge. Because cars have brakes.
You need to start matching speed at the start of the signage for the merge. At that point it’s no longer just a lane, it is a lane with restrictions.
You’re not actually increasing total throughput by speeding ahead, you’re only changing the order. The total throughput is determined by the flow of traffic after the constriction point. That flow is smoothest when drivers match speed.
What you’re missing is that the “closing lane” is often designed to be utilized to prevent traffic from backing up into another traffic control device.
While you’re “matching speed” with the open lane that’s hardly moving- traffic has now backed up into an intersection and caused gridlock on cross streets for miles behind you.
So while “total throughput” on YOUR journey has remained the same you may be causing chaos to the roads around you.
Your best bet is to just assume the traffic engineers who designed the closure know better than you.
The middle and last scenario both have people merging in at the end, but only the scenario with matching speed has smooth high throughput flow that alleviates congestion.
The lane hardly moving is usually because of uneven merging at the closure point. If everyone matches speed then both lanes are filled equally. That’s what the traffic engineers say is best.
There’s a problematic entry ramp that I used to drive every day on my commute. Traffic would back up around it every day in rush hour. When I matched speed and zippered in at the end, the congestion actually started to clear a little as the lane being merged into started moving substantially faster without people cutting in out of turn.
This does not address my point at all. I agreed that your suggestion would not necessarily negatively impact the total throughput on your route.
My point was that your route does not exist in a vacuum and the utility of the open lane may not be obvious without having the same information available as the traffic engineers who designed the closure.
Matching speed does a better job of filling both lanes evenly and reduces the amount of backed up traffic. The slow lane is what backs up to prior intersections. Matching speed is what allows the slow lane to clear up and prevent affecting upstream intersections. You’re point isn’t actually relevant to what I’ve described because the lane is fully utilized in a proper zipper merge with speed matching.
So I’m not ignoring the purpose of the merge lane, and I’m not advocating early merging. I’m describing the key aspect of zipper merging that the cruise ahead people are missing.
I mean speeding at a far higher speed than the other plane and then suddenly slamming on the brakes and forcing themselves into the other lane. Rushing to merge, not just zipper merging at a similar speed.
If the lane being used is still open for forward traffic, that is a completely legitimate zipper merge, although it would be safer to match speed more gradually and, of course, wait for an appropriate space to merge into. As a hypothetical, that’s a borderline case, and it’s certainly possible to adjust the details of the hypothetical to make the merging driver into the dick. But I’m not sure that’s a useful pursuit.
How is matching speeds to merge and finding a space an edge case? That is how merging works.
Not matching speeds is how people going slower than the flow of traffic when merging from on ramps causes issues. Matching speeds when merging is crucial.
I am not calling it rushing because they are passing, but because they are going a significantly higher speed when starting to merge, requiring them to slam on the brakes and cause the same issues that merging too early causes.
Like going 20+ mph over the posted speed, not just going the speed limit in the open lane.
People who stay in the open lane and don’t pass in the no passing zone and just zipper merge at the end are not the people I am talking about when I say rushing.
You can either work with human nature, or try to work against it. But if you choose the latter, you’re gonna have a bad time.
As someone with a background in traffic engineering, I care about what actually works. Making yourself feel good by passing judgement on drivers doesn’t actually do anything to solve the problem.
Because it is stupid to blame early merging people instead of just assuming the speeders are the same people that speed and do shitty sudden lane changes in normal traffic.
No, it fucking doesn’t because we don’t live in a perfect world and entitled/dumbasses fill the road. If I’m in the right lane and some chucklefuck is matching my speed in the on-ramp next to me and doesn’t either speed the fuck up or slow the fuck down in the 2 whole minutes they have in that lane, they’re gonna end up slamming their brakes at the end. All it would take is a modicum of awareness to get over and stop this awkward bullshit. That’s just ONE example.
This isn’t a traffic jam. This isn’t the middle of Delhi. We’re talking about normal everyday traffic.
It’s 2 cars in a 4 lane highway, and the dumbass can’t even merge.
And no, it’s not my responsibility to make sure they get over. I’m not hand holding idiots.
Point is, we don’t live in a fucking vacuum and all it takes is opening your eyes and judging the situation in front of you accordingly.
I am generally a nice-ish person. I’ll try to slow down a little to give them more room. And then they just slow down too because they don’t know how to drive without matching speed with a car next to them. And, fortunately, they aren’t looking at me so I can’t even wave them in. So it is just a waiting game of “Are they going to speed up and cut me off so that I have to slam on the brakes, or are they going to slam on the brakes at the last second and stop their lane until my lane stops to let them in?”
Nobody is saying to force your way in to the merge lane five miles ahead of the closure. If traffic is moving along, move along. But if you see an opening and know the lanes are going to merge? Merge then and there.
We’re talking about two different things then. Open road, light fast-moving traffic, lane ending - the “merge zone” lengthens with that speed and space.
Heavy slow-moving traffic, lane ending, use the lanes which are available and zipper merge at the end. Merging too soon in this situation does create congestion.
In a vacuum it creates congestion, in reality things can be different, usually shitty drivers
For example: I drove a large truck most of last year and people simply will not let you in if you attempt to zipper mete properly in a vehicle deemed slow or cumbersome. They will literally close in as tight as they can on each other knowing that should you hit them you’ll be found at fault
This can even result in the people in the lane behind said vehicle to start zippering at the point behind the vehicle, essentially moving the zipper a car length down the highway. These people also frequently close in and box out that cumbersome vehicle as well.
This technically keeps traffic flowing, but massively breaks flow when the vehicle finally managed to edge enough into the lane to force a merge or someone gives them room to actually get in
I always defer to commercial vehicles on the road, no matter what. Those people are at work; I’m not. It’s not a perfect analogy, but I also don’t go into retail stores and get in the way of employees, either.
Theory: Everyone down voting you has never driven outside the US.
We don’t teach the proper way to zipper merge, so people block those doing it for cutting in line. It’s a different culture that should be changed for efficiency, just like middle lane squatting, but it’s just not important enough to address.
I mean. The UK (particularly Northern Ireland) are gods of zipper merging. It is like all of the queuing is to train them for exactly that. Every single time I felt like an asshole because I slowed down even a km/h or two to “let someone in” when they knew exactly how much space they needed and had it under control.
Germany… I am honestly gobsmacked at how bad Berlin and Frankfurt were at zipper merging. It felt like if I suddenly discovered that nobody in mainland China could make rice without a rice cooker. Like… I think the US might somehow actually be better. And we are HORRIBLE at zipper merges. At least New England, if not Chicagoland.
If I am traveling internationally and driving? The bare minimum is that I’ll ask the person at the rental counter if there are any “gotchas” to be aware of. And if I have any friends in the area, I’ll chat with them on a hangouts/discord call before I fly over.
Hell, I SHOULD do the same when driving domestically but at this point I can handle NYC, LA, Boston, Chicago, and all the stupidity in between so… fuck it and sorry if I cut you off.
But also…
Theory: People think speaking in absolutes based on driver’s ed manuals is stupid? And you actually have to understand “the rule of the road” and how to drive defensively.
It’s not just Berlin and Frankfurt, the autobahn is known for two things in the countries surrounding Germany; no speed limit and people completely skipping the acceleration lane.
In traffic circles, even if someone messes up, the problem is usually resolved and the circle is back to normal operation within a minute or so. Unless someone is literally camped in the middle of the circle, life finds a way.
The number of people I’ve seen use the inner lane to turn out of the circle pisses me off. Change lane to outer circle, then exit the circle. The number of times I’ve nearly been hit because some asshat in a giant truck decided they own all the lanes is too high to count.
My favorite is when they are in the right lane, merge to the middle and back out when going straight so they don’t have to actually slow down and go in the round outside lane, defeating the point of the roundabout.
You mean they just cut through the circle like it’s a straight-away? There’s a circle near me that has 1 entrance-exit pair that happens all the time. And an entrance b/t the two is really hard to see when entering and has nearly zero visibility to that left entering lane. I’ve nearly been creamed by people doing 30mph through there like that.
It’s a shittily designed roundabout but they need some traffic calmers there.
Yes. I have noticed that newer circles discourage this by having tighter entrances and exits that limit the ability to do so, but a lot of older ones were gradual enough that you could go through it without even turning the wheel.
The main problem with zipper merges in practice are selfish people who rush to zipper and cause even more congestion because of their erratic attempt to merge. Like traffic circles they work great when everyone is doing it right and they cam get really messed up when people do it wrong.
It would be great if zipper merging was taught as part of getting a license. Or they actually required someone to learn how to zipper merge as part of their license renewal.
Do you mean “rush to zipper” as in “using an open lane to move forward and then zipper merge into the remaining lane when that one closes?” That is precisely what you should do.
The problem is the selfish people who refuse to let those people actually zipper merge, like OP.
@Nougat
It’s hard to discuss zipper merging because people use to justify all sorts of dick behavior. Zipping through an empty left turn only lane to skip to the head of a right turn only lane for example. That’s not an example of zipper merging but there’s tons of people who I’ve seen argue that’s acceptable behavior.
Those people are assholes.
We agree that that’s not what we’re talking about, and those people are wrong. That wasn’t hard at all.
The issue is, at the end of the day, that nobody ever seems to know how to keep a decent distance away from the car in front of them. It doesn’t matter how slow traffic is, leave some space in front of you. It gives you room to slow down in case something happens, and it gives everyone else room to merge.
Zipper merging requires matching speed with the lane you are merging into so that drivers can make gradual changes in speed to make an opening for the person merging. That avoids sending a wave of brake slams that results from sudden unexpected lane changes. If you’re passing a bunch of people, you’re probably not doing a zipper merge.
You’re also much less likely to end up with someone not letting you over if they see you matching speed instead of speeding up to the merge point.
If you’re passing a bunch of people, you are using the open lane to travel. By the time the lane you are in comes to an end, you then modulate your speed to match traffic in the slower lane, and merge. Because cars have brakes.
You need to start matching speed at the start of the signage for the merge. At that point it’s no longer just a lane, it is a lane with restrictions.
You’re not actually increasing total throughput by speeding ahead, you’re only changing the order. The total throughput is determined by the flow of traffic after the constriction point. That flow is smoothest when drivers match speed.
What you’re missing is that the “closing lane” is often designed to be utilized to prevent traffic from backing up into another traffic control device.
While you’re “matching speed” with the open lane that’s hardly moving- traffic has now backed up into an intersection and caused gridlock on cross streets for miles behind you.
So while “total throughput” on YOUR journey has remained the same you may be causing chaos to the roads around you.
Your best bet is to just assume the traffic engineers who designed the closure know better than you.
youtube.com/watch?v=cX0I8OdK7Tk
The middle and last scenario both have people merging in at the end, but only the scenario with matching speed has smooth high throughput flow that alleviates congestion.
The lane hardly moving is usually because of uneven merging at the closure point. If everyone matches speed then both lanes are filled equally. That’s what the traffic engineers say is best.
There’s a problematic entry ramp that I used to drive every day on my commute. Traffic would back up around it every day in rush hour. When I matched speed and zippered in at the end, the congestion actually started to clear a little as the lane being merged into started moving substantially faster without people cutting in out of turn.
This does not address my point at all. I agreed that your suggestion would not necessarily negatively impact the total throughput on your route.
My point was that your route does not exist in a vacuum and the utility of the open lane may not be obvious without having the same information available as the traffic engineers who designed the closure.
Matching speed does a better job of filling both lanes evenly and reduces the amount of backed up traffic. The slow lane is what backs up to prior intersections. Matching speed is what allows the slow lane to clear up and prevent affecting upstream intersections. You’re point isn’t actually relevant to what I’ve described because the lane is fully utilized in a proper zipper merge with speed matching.
So I’m not ignoring the purpose of the merge lane, and I’m not advocating early merging. I’m describing the key aspect of zipper merging that the cruise ahead people are missing.
I mean speeding at a far higher speed than the other plane and then suddenly slamming on the brakes and forcing themselves into the other lane. Rushing to merge, not just zipper merging at a similar speed.
If the lane being used is still open for forward traffic, that is a completely legitimate zipper merge, although it would be safer to match speed more gradually and, of course, wait for an appropriate space to merge into. As a hypothetical, that’s a borderline case, and it’s certainly possible to adjust the details of the hypothetical to make the merging driver into the dick. But I’m not sure that’s a useful pursuit.
How is matching speeds to merge and finding a space an edge case? That is how merging works.
Not matching speeds is how people going slower than the flow of traffic when merging from on ramps causes issues. Matching speeds when merging is crucial.
Or just do what they do in Ontario, drive on the shoulder and zipper merge onto the 1 actual lane.
No, the problem is the people who incorrectly merge early, making “rushing” possible.
I am not calling it rushing because they are passing, but because they are going a significantly higher speed when starting to merge, requiring them to slam on the brakes and cause the same issues that merging too early causes.
Like going 20+ mph over the posted speed, not just going the speed limit in the open lane.
People who stay in the open lane and don’t pass in the no passing zone and just zipper merge at the end are not the people I am talking about when I say rushing.
Right, and the real fault lies with the early mergers who cause the open lane to exist in the first place, not the opportunistic drivers who fill it.
Early mergers don’t make people speed in the open lane and abruptly merge in an unsafe manner.
You can either work with human nature, or try to work against it. But if you choose the latter, you’re gonna have a bad time.
As someone with a background in traffic engineering, I care about what actually works. Making yourself feel good by passing judgement on drivers doesn’t actually do anything to solve the problem.
Are you saying that human nature is to speed in the open lane if other people merge early?
Yeah, it sure seems that way. Why, do you doubt it?
Because it is stupid to blame early merging people instead of just assuming the speeders are the same people that speed and do shitty sudden lane changes in normal traffic.
The other issue is people who have no spatial awareness of their vehicle and need like eight car lengths to merge over.
Done with a modicum of competence: Zipper merges are efficient and you should only merge near the end
In reality? If you see an opening, merge over sooner than later to prevent disruptions to traffic
This actually creates disruptions in traffic. Use all lanes, zipper merge at the end.
No, it fucking doesn’t because we don’t live in a perfect world and entitled/dumbasses fill the road. If I’m in the right lane and some chucklefuck is matching my speed in the on-ramp next to me and doesn’t either speed the fuck up or slow the fuck down in the 2 whole minutes they have in that lane, they’re gonna end up slamming their brakes at the end. All it would take is a modicum of awareness to get over and stop this awkward bullshit. That’s just ONE example.
This isn’t a traffic jam. This isn’t the middle of Delhi. We’re talking about normal everyday traffic. It’s 2 cars in a 4 lane highway, and the dumbass can’t even merge.
And no, it’s not my responsibility to make sure they get over. I’m not hand holding idiots.
Point is, we don’t live in a fucking vacuum and all it takes is opening your eyes and judging the situation in front of you accordingly.
God yes.
I am generally a nice-ish person. I’ll try to slow down a little to give them more room. And then they just slow down too because they don’t know how to drive without matching speed with a car next to them. And, fortunately, they aren’t looking at me so I can’t even wave them in. So it is just a waiting game of “Are they going to speed up and cut me off so that I have to slam on the brakes, or are they going to slam on the brakes at the last second and stop their lane until my lane stops to let them in?”
Nobody is saying to force your way in to the merge lane five miles ahead of the closure. If traffic is moving along, move along. But if you see an opening and know the lanes are going to merge? Merge then and there.
I was taught to move left in that case - it eliminates any potential confusion and moves you completely out of the interaction.
We’re talking about two different things then. Open road, light fast-moving traffic, lane ending - the “merge zone” lengthens with that speed and space.
Heavy slow-moving traffic, lane ending, use the lanes which are available and zipper merge at the end. Merging too soon in this situation does create congestion.
In a vacuum it creates congestion, in reality things can be different, usually shitty drivers
For example: I drove a large truck most of last year and people simply will not let you in if you attempt to zipper mete properly in a vehicle deemed slow or cumbersome. They will literally close in as tight as they can on each other knowing that should you hit them you’ll be found at fault
This can even result in the people in the lane behind said vehicle to start zippering at the point behind the vehicle, essentially moving the zipper a car length down the highway. These people also frequently close in and box out that cumbersome vehicle as well.
This technically keeps traffic flowing, but massively breaks flow when the vehicle finally managed to edge enough into the lane to force a merge or someone gives them room to actually get in
Shitty drivers create congestion, yes.
I always defer to commercial vehicles on the road, no matter what. Those people are at work; I’m not. It’s not a perfect analogy, but I also don’t go into retail stores and get in the way of employees, either.
Theory: Everyone down voting you has never driven outside the US.
We don’t teach the proper way to zipper merge, so people block those doing it for cutting in line. It’s a different culture that should be changed for efficiency, just like middle lane squatting, but it’s just not important enough to address.
I mean. The UK (particularly Northern Ireland) are gods of zipper merging. It is like all of the queuing is to train them for exactly that. Every single time I felt like an asshole because I slowed down even a km/h or two to “let someone in” when they knew exactly how much space they needed and had it under control.
Germany… I am honestly gobsmacked at how bad Berlin and Frankfurt were at zipper merging. It felt like if I suddenly discovered that nobody in mainland China could make rice without a rice cooker. Like… I think the US might somehow actually be better. And we are HORRIBLE at zipper merges. At least New England, if not Chicagoland.
If I am traveling internationally and driving? The bare minimum is that I’ll ask the person at the rental counter if there are any “gotchas” to be aware of. And if I have any friends in the area, I’ll chat with them on a hangouts/discord call before I fly over.
Hell, I SHOULD do the same when driving domestically but at this point I can handle NYC, LA, Boston, Chicago, and all the stupidity in between so… fuck it and sorry if I cut you off.
But also…
Theory: People think speaking in absolutes based on driver’s ed manuals is stupid? And you actually have to understand “the rule of the road” and how to drive defensively.
It’s not just Berlin and Frankfurt, the autobahn is known for two things in the countries surrounding Germany; no speed limit and people completely skipping the acceleration lane.
The United States has a strong general culture of “I got mine, fuck you.” That is certainly playing a part in this thread.
In traffic circles, even if someone messes up, the problem is usually resolved and the circle is back to normal operation within a minute or so. Unless someone is literally camped in the middle of the circle, life finds a way.
The number of people I’ve seen use the inner lane to turn out of the circle pisses me off. Change lane to outer circle, then exit the circle. The number of times I’ve nearly been hit because some asshat in a giant truck decided they own all the lanes is too high to count.
My favorite is when they are in the right lane, merge to the middle and back out when going straight so they don’t have to actually slow down and go in the round outside lane, defeating the point of the roundabout.
You mean they just cut through the circle like it’s a straight-away? There’s a circle near me that has 1 entrance-exit pair that happens all the time. And an entrance b/t the two is really hard to see when entering and has nearly zero visibility to that left entering lane. I’ve nearly been creamed by people doing 30mph through there like that.
It’s a shittily designed roundabout but they need some traffic calmers there.
Yes. I have noticed that newer circles discourage this by having tighter entrances and exits that limit the ability to do so, but a lot of older ones were gradual enough that you could go through it without even turning the wheel.
Renewal? Wht is stranger thing.
A thing that existed in the long, long ago in the last millennium.
Seriously, I think I had one license renewal in the late 90s where I had to take a written test and since then I just have to prove I still exist.