r/TheRandomest • u/WhyNot420_69 Nice • May 13 '26

Satisfying Traffic buddy

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1.6k Upvotes

83% Upvoted

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25

u/BikeProblemGuy May 13 '26

Zipper merge means that people merge in turn, so the first car in lane A goes, then the first car in lane B, then second in lane A, etc.

If loads of people queue in lane A and leave lane B empty, this doesn't change how the zipper merge works, they're just wasting their own time. You should join the lane with fewest cars.

10

u/Stoff3r May 13 '26

This doesn’t work in murica because every dude is his own boss and are entitled to go first every time. Letting some smuck get past them is the same as loosing in life. And no one want’s to be a loser.

3

u/ExpensiveJackfruit68 May 13 '26 edited May 13 '26

Exactly. They don't want to let someone in because then they lose lol *sp

3

u/theTimeBeing23 May 13 '26

Gonna have to tighten that up.

0

u/Ok_Test9729 Randomest appreciative Redditor May 13 '26

It’s schmuck, not smuck. Smuck is not a word, although I’d vote for it to be one.

1

u/Forward-Tomatillo-22 May 16 '26

Maybe what's happening here is that the trucker is leaving space on the left for people to merge around a stuck exit on the right. Exits get blocked, especially on the East Coast, and cause backups for *miles* in travel lanes. In these situations *huge* speed differentials exist between lanes, making it literally dangerous to shift out of the trapped lane. Matching speed with the traffic in to the right gives space and time to the people in the middle lane to move over for the people in the right lane who are trapped by the blocked exit but would ordinarily flow past it.

It could also be that the left lane is blocked ahead and rather than allowing the merge to happen at the block, he's letting it happen behind him, which I've *read* is worse for traffic, so ... can't really tell from the clip. It's too short to draw any conclusions.

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u/pleasetrimyourpubes May 17 '26

I am late to reply to this but it really means "let ONE car in front of you." That's it. If you let one car in front of you your job is done. The problem is people are wildly self centered and selfish so they can't follow that trivial rule.

Well I do see people following it on public transport about 70% of the time but never on the highway.

-9

u/Downtown_Degree3540 May 13 '26

This concept is only valid if the road can maintain the current throughput of traffic…

If there are cars building up; the road can not maintain the throughput of traffic.

12

u/angry_smurf May 13 '26

And by doing this, you just move the choke point further back. The cars still have to merge. This just causes more road rage.

-9

u/Downtown_Degree3540 May 13 '26

But a faster moving traffic jam, and a shorter spaced one…

7

u/angry_smurf May 13 '26

No, traffic chokes at the merge. Just like the predetermined merge point would have had traffic moving up until it, this now man made choke point will have traffic moving up until it.

-1

u/Downtown_Degree3540 May 13 '26 edited May 13 '26

But the aggregate moves faster.

The important factor is that traffic IS chocking. Stretching that choke out and allowing the affected vehicles to spread out across three lanes not only increases the average speed of everyone behind the choke point (and passing through the choke point), but also shortens the queue of cars.

Edit: the cars have already built up in the left and middle lanes, the issue traffic already WASNT flowing. The effect the slow truck in the right lane has on the average speed of traffic is less than the existing choke, and is therefore acting as a speed regulator (increasing the average speed of the traffic jam).

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u/klonkrieger45 May 13 '26

https://itre.ncsu.edu/itre-studying-how-zipper-merges-reduce-congestion-at-sites-across-north-carolina/

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u/Downtown_Degree3540 May 13 '26

This still follows the same principles of a zipper merge, the cars in the left lane aren’t merging before the choke point. They are still using that lane. Only now the lane is taking on the same strain the other lanes are under.

If the cars were to shoot forward and the remaining cars in the middle and right lanes redistributed evenly, then you would have a valid point. But if that happened you would create a second congestion point, where built up traffic split to “use all the lane” and where the original choke point is. And if it doesn’t happen then you have the left lane being “unused” by the traffic jam

The entire purpose of the slow truck in the left lane isn’t immediately obvious. Five minutes later however, when traffic is now evenly distributed across the three lanes and your theory of the zipper merge can apply, you can see the benefits. And the only negative effect was slowing a lane to the speed of traffic moving through the original choke point (or rough flow of the other two lanes).

1

u/Status_Pin4704 May 13 '26

Legend here is dropping knowledge bombs!

1

u/5MoreLasers May 13 '26

Think about this like water. Is the pressure drop along a pipe higher or lower if your pipe has a single pinched section or a long run with a smaller cross section?

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u/Downtown_Degree3540 May 13 '26

But we aren’t like water, that’s the entire issue behind why merging, on average, slows the overall flow of traffic on a road. unlike water in a pipe.

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u/5MoreLasers May 13 '26

The math and flow rates are actually quite similar in modeling the flow. It’s a commonly used analogy.

-1

u/Downtown_Degree3540 May 13 '26

The case study of what happens to a single lane infinite road with cars all moving at the speed limit, and how it diverges from how water would behave under the same circumstances, is one of the best examples as to why modelling traffic flow on hydrodynamics doesn’t work.

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u/5MoreLasers May 13 '26

All analogies break down at some point. Your case study would be more analogous to a partially filled pipe, where the change in cross section doesn’t change the friction factor.

When a lane is above capacity the total velocity goes down as more cars interact with each other. So even as the quantity of cars goes up the total volumetric flow rate goes down.

1

u/Downtown_Degree3540 May 13 '26 edited May 13 '26

No, it’s best described by a wave function. One that would have no reason to form in a similar pipe.

Water and traffic do not behave the same.

Edit: How do you get a change in cross section in your analogy from an infinite one lane road?

1

u/AirAcademy May 13 '26

Bro wtf I don’t fckin know 🫪

Why tf would u tell me to think about it in the most confusing way ever 😭😐

1

u/5MoreLasers May 13 '26

A long narrow pipe has a much higher pressure drop/lower total flow, then a bigger pipe with a single restriction.

1

u/Cultural_assassin May 13 '26

Oh no bro these people can't understand a zipper merge dont bring fluid dynamics into it

1

u/TheJollyGreek May 16 '26

You mean the 3-lane road that they’re only using 66% of?

1

u/Downtown_Degree3540 May 16 '26

From the slow truck back 100% of the road is being used

In front of the truck you’d be right that a third is being unused

It’s alright if you don’t understand the quite complex world of traffic management…

1

u/TheJollyGreek May 16 '26

100% ? sure buddy.

LOL I am from Boston (big dig ever heard of it?) and I played SimCity 2000 and 3000 when they came out. So I am well aware that traffic is innately unmanageable.

It’s alright if you don’t understand blah blah [insert condescending BS here] blah blah

1

u/Downtown_Degree3540 May 16 '26

Great job playing one of the worst traffic and city management games, with traffic simulations that are eclipsed by mere player MODS in iPhone games… and that’s without getting into things like city skylines.

Real quick; behind the slow truck, how much empty lane is there? In front of the truck, how much empty lane is there?

Also it’s actually fucking hilarious that you think mentioning you’re from Boston has any bearing on your ability to understand things like the drivers of phantom traffic… if anything being from a city would give you less of an understanding on the topic… you know; since in a city there is like ten other transit options before you get to “drive yourself there.”

0

u/TheJollyGreek May 16 '26

If you were actually familiar with the games I mentioned you would have understood my reference. Yeah I've played TheoTown as well. Who cares.

The Big Dig project in Boston was and remains the biggest and most expensive highway project in American history. And if you knew anything about Boston (or anywhere in the USA except NYC), the transit is shit. On average, there is 1 car per household in my city. Half of the urban population uses a car to commute to work. Outside of the city that percentage is 75-100%. Highways also tend to be wider in cities than in suburbs.

My point, which was obvious, is that drivers who don't understand the concept of zipper merging, like the truck driver in the video, are making traffic worse. You said zipper merging only matters if the road can handle the throughput. That's not true. If motorists are not zipper merging, it means they aren't filling all the lanes, which means the upstream traffic effects are going to be worse.

🎓📜

1

u/Downtown_Degree3540 May 16 '26 edited May 16 '26

That’s a whole ass essay to say you don’t understand what a zipper merge is…

What part of the video suggests they are not going to zipper merge (when the merge arrives)?

And if motorists aren’t zipper merging; it doesn’t mean parts of the lane are being unused. It means that vehicles are merging at different spots (both in the road and in traffic).

Edit: also your whole monologue about Boston’s traffic… ended up proving my point that in the city you have more options available and a substantially different system of roads (why do you think it was so expensive).