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Comment by malandrew | Hacker News Reader

That video explanation made no sense to me. Basically the "interface" presented to the drivers has not changed, so why would drivers deviate from how they currently merge? Because the government said so? I don't see this working.

However there are two solutions that could promote zipper merging:

(1) Force both lanes to the center before moving that center lane to the side that is available ahead:

    ____________________________________________
                          \________/
    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ________
                           ____________/
    ______________________/_____________________

(2) Present a long-barrier between both lanes well before the merge that only permit late merging, so that those in the continuing lane feel morally obligated to let those queued up in.

    ____________________________________________
                         
    _ _ _ _____________     ____________________
                           /
    ______________________/_____________________

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In New Zealand we just have signs like this all over the place:

http://i.imgur.com/AtaDOGX.jpg

Its pedantic, but I think this is sublty different than what is being dicussed here. All over the US, there are situations where 2 lanes converge to 1 and drivers "take turns" merging. But I think the scenario that is being discussed is a little different, where there is 1 "working" lane and one "closed" lane, the thought process of drivers in the lane that they know is 'closed' up ahead is to merge early.

I wonder if cultures where queueing (like, in the grocery store) is not as common as in the US have this problem? I suspect not.

We have temporary merge like a zip signs as well for road works, I just didn't see one on Google Image Search. They only tend to put those out for fairly large multi-week road works I've noticed though.

I live in the Netherlands, but drive through Belgium when driving home from work.

There is one area where a permanent two-lane road merges into a single lane. The funny thing is that (mostly) Belgians never use the second (left) lane that eventually merges into the single right lane.

This always seems stupid to me, because it increases the length of the traffic jam so much, that the traffic jam goes all the way over a roundabout, causing stops for all drivers, even the ones not going in the same direction as us.

The worst thing is, whenever I use the left lane - which I do all the time (and in return, pass 60 cars waiting in line), people sometimes get so angry that I've had two trucks in the past few months hitting the gas and blocking the left lane so no one can pass anymore.

Crazy people...

Last month a new sign was installed along the road "Please use both lanes, drive all the way to the front and THEN start merging". Even now, people still choose to wait in line at the right lane. It is as if people feel guilty when they see a whole lane being empty and available to drive on.

This is what it's like in Scotland!! People here get SO angry, thinking that you have "skipped" all the other patiently waiting people... And then they don't let you merge! And it makes absolutely no sense to me, because they cause one reallllyyyy long traffic jam then...

The two lanes in the picture merge into one "center" lane. I've never seen that here in the states. Typically it is one lane merging into another lane. I'd wager the "merge into the shared center lane" makes the zipper protocol more obvious.

I think you misinterpreted the picture - the left lane ends and merges with the right, as when joining a motorway (we drive on the left). You can see the real thing in the photo above the closest two cars.

The zip system is used ubiquitously here - I didn't even know there were other systems, so I was curious to see what new thing the article was about. From what I understood, the alternative is not really a "system"?

To my understanding in intensive traffic it's more about uniform and predictable behaviour.

First option will not improve since (at least in Europe) it just changes lane priority. In linked article's merge case priority traffic is in left lane, since right one merges. In your center merge case priority traffic is on the right (when doing simultaneous merges to center lane, one on the right has priority over the one on the left). So it probably won't change anything.

Barrier option is much better, but it has challanges and restrictions of their own.

Edit: Oh, and I forgot to mention that over here in Latvia I see people starting to respect zip merging. It's all in our head. Not because government said, but because everybody follows simple rule and everybody gets home faster and with less stress :)

Option 2 physically walls off the Late Mergers in addition to mentally (in the minds of the Free Laners), making them easier to ignore.

I like option 1 because it forces everyone to move.

Yeah, option 2 would lead to someone hestitating/stopping in that lower lane. Then that whole lane is stopped because the front driver is too afraid to merge into moving traffic, and the moving traffic is going too fast to stop and let a lower lane driver in.

Good thinking. Apparently your option 2 was implemented (and considered an innovation) around where I live. Here's a picture from 2007: http://www.strassen.nrw.de/_down/pi-070322-03.jpg I don't know if they're still doing it. (Late merging has long been the default in Europe and is taught in driver's ed. However people seem to do it more reliably when reminded of the practice.)

I wonder if there's an option 3, install a mobile traffic light that allows one lane only at one time, in sequences of one minute or so each, i.e Alternating red and green lights, so that there is no need for merging. This way there's no slowdown caused by the merging, I feel that this method may actually make it faster overall.

    ____________________________________________
                      Green   
    _ _ _ _ _ _ _ _ _ _     ____________________
                      Red  /
    ______________________/_____________________


    ____________________________________________

                     Red    
    _ _ _ _ _ _ _ _ _ _     ____________________
                    Green  /
    ______________________/_____________________

Temporary traffic lights is definitely an interesting idea. It would however require a long barrier, otherwise, what is to stop people at the end of the stopped lane from trying to merge into the moving lane.

Another idea is a temporary speed bump in the lane that is not ending.

Except that red means "stop", so presumably that whole "you don't have to stop" thing wouldn't work.

I was driving in Atlanta a few weeks ago and was in a situation where two two lane roads converged to a single two lane road. Each side had this exact thing and it actually worked really well. Not the same as a construction zone but I think would be a helpful tool.

The picture Negitivefrags posted shows a similar setup currently in use in New Zealand (although it's a permanent merge instead of temporary construction)

http://i.imgur.com/AtaDOGX.jpg

Hey, I'm from Minnesota. Here is a merge spot that I take pretty often: https://www.google.com/maps/@45.008271,-93.203054,3a,75y,63....

Unfortunately, this spot still has lots of early merging. Some high traffic areas have special lanes for zipper merging, but I think the emphasis is on changing drivers' habits through public service announcements rather than redoing the lane structure.

Option 1 leads to "no, after you" behavior, steers two cars directly at each other, and probably would be a disaster.

Speaking about educating drivers, I wish we could just kill that mentality once and for all. It drives me crazy when someone obviously beats me to a stop sign, then waves me through as though they're doing me a favor. No my friend, you're just making it slower for both of us by not following the established rules of the road.

Thankfully my city is replacing as many stop signs as possible with traffic circles, where you'd have to be a complete idiot to yield to someone who got there after you.

> Thankfully my city is replacing as many stop signs as possible with traffic circles, where you'd have to be a complete idiot to yield to someone who got there after you.

In Seattle, we have traffic circles in many of our residential neighborhoods. People still do this here. Another common thing is people taking lefts by just driving on the left side of the circle (I've had people honk at me for taking lefts the correct way)

we have a couple around here near campus. The problem is shockingly few people know how to behave in a traffic circle.

"few people know how to behave in a traffic circle"

Tell them this: imagine a big circular road. Then imagine other roads joining it with T junctions. Then imagine the road is one-way. Finally just shrink the road in your head.

That's all it is!

There's one more rule: traffic on the circular road has priority.

That rule already applies. It's no different on a circular road or roundabout; traffic already on a road has priority over traffic turning onto it.

"Traffic already on a road" is a concept that does not apply in this scenario, as all traffic is already on a road in all cases. There is no a priori way to distinguish between the circular road and the roads leading towards it.

In countries where you drive on the right, I believe the typical default rule is that traffic coming from the right has priority. In roundabouts, this would mean that traffic on the roundabout must wait for those joining it. However, the rule is reversed for roundabouts. (This definitely applies to Germany, and I suspect that it applies in most other countries as well.)

I guess that depends where you live. That thing is intersection like any other and the one on the right has a priority. So, unless there is a sign, the car about to enter the circular road should go first. And yes, all roundabouts have signs in here.

I live in Australia, but I've also driven in the UK and parts of Europe. Any roundabout I've used has worked in the same way -- as you approach the roundabout, you must give way to vehicles already on the roundabout.

Relevant to the circular road with T-intersection analogy, I'm reading the Wikipedia page[0] on T-intersections and I must admit the concept that "vehicles on the right always have the right-of-way" makes absolutely no sense whatsoever. But I suppose that weird rule would screw up the circular road metaphor.

[0] https://en.wikipedia.org/wiki/Three-way_junction#Right-of-wa...

There's one more rule: traffic on the circular road has priority.

This is how it would work in a sane system, but they don't always work this way. I can think of several examples in New Jersey, particularly around Flemington, where the circle manages the intersection of two roads having different importance. In these cases, the important road is given the right-of-way all the way through the circle, and those coming around the circle from the lesser road are required to yield.

They have signs that say "Yield to Traffic in Circle" at each entry point. I agree it is a simple concept yet people seem to struggle with it around here.

They're trivial to learn. I don't see how people can use that as an excuse. Imagine someone saying "I don't understand traffic lights, they're so confusing."

We have the same problem. Unfortunately, it's compounded by the fact that the local municipality here likes creating very small traffic circles with a small bump in the middle. The end result is that people end up treating them like 4-way stops and yield as such.

I've sometimes waited at those circles. Many of those neighborhoods you mention also have streets just wide enough for one vehicle at a time to get through. I'd rather wait at the circle for an oncoming vehicle than have to worry about who will yield to whom and whether there's a sufficient gap in the parked cars to do so.

This can be seen in miniature on my university campus. Thankfully some new surface markings make it slightly more obvious that they are going the wrong way.

Out of curiosity, is your traffic circle configured in a way where taking that left requires no turning while the proper right actually takes effort?

Pretty much. Most of the ones that I've seen here in Seattle are basically small landscaped areas with a curb in the middle of the intersection. Probably not much more than six feet in diameter or so. (At the one nearest my house the sidewalk corners aren't even rounded any to accomodate them.) These really aren't true roundabouts.

But yes, turning left instead of going around them should take no more effort than a typical left turn between small streets, while doing it the proper way requires a fairly tight turn. They seem mainly designed to force cars to slow down.

> you'd have to be a complete idiot to yield to someone who got there after you.

You'd be surprised. Or else the vast majority of drivers around here are complete idiots. They basically treat traffic circles like a confusing 4-way stop sign. It's infuriating.

This is the worst when you're on a bike -- the car tries to be nice and let you go, but you can't assume that they're not going to zip out and kill you if you do, so everyone just fucking sits and waits, when you could have just zipped through behind them. It's insane.

I reckon you could do the following to fix this issue:

(1) add the barrier from option 2 to option 1, so that all the merging happens at the front.

(2) Keep the "make both parties move structure" from option 1, but don't make it 100% symmetrical. Instead, nudge the top lane down just enough so they are forced to slow down and somewhat zipper in with the bottom lane.

I like the idea of #1. But it seems from my experience in the U.S. and Canada, that there is a tendency towards unambiguous right-of-way. That tends to rule out collaborative scenarios where there's no clear "winner" when two cars are competing for the same resource. Which is a shame, because making this collaborative is exactly what will change the mentality (i.e. you can't ignore the drivers trying to merge, because you're trying to merge too).

Even with zipper merging the right-of-way is going to be on the person who is staying in their own lane.

I'm not sure if my experience is regional, or even imagined, nor do I know the reason...I'd imagine it makes assigning blame in an accident much easier, but that's a really crappy basis for traffic rules.

#1 is what happens in Fremont,CA when cops are running a DUI check, works fairly well.

> so that those in the continuing lane feel morally obligated to let those queued up in.

I'm pretty well convinced that we'd never hit critical mass of drivers that feel morally obligated to even moderately inconvenience themselves to benefit the merging of others. That merge pattern is a recipe for stalled traffic in the right hand lane.

First one seems workable, though.

Yes! #1 is what I was thinking too. Remove the dominance/subordination from the merging and it's obvious what one is supposed to do -- zipper right in one at a time.

I like option one, but I don't think it works if there are more than two lanes

Option 1 sounds great in theory, but given that most merges are the result of temporary lane closures, completely impractical (since road work usually goes one lane at a time)

How is it any more impractical than how temporary lane closures are currently done? It can still be done with cones or barrels and the end result is exactly the same.

The point is, suppose they are repaving the road one lane at a time. (Or, repaving half of a 2-lane road)

You simply move up the half-merge of each lane to suit. It's rather clearly explained in the diagram, where you can see it does end in one and only one lane actively in use. You'd do the "merge half of each lane" part while the road still supports two lanes, just as you already have to account for with current temporary traffic control devices.

Ah. I see; I am not a very good ASCII art interpreter, is the problem.

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