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Zipper merging is the optimal solution. People early merge because they think it is the optimal/moral/better/'done my part' solution. If everyone knew about zi

Zipper merging is the optimal solution. People early merge because they think it is the optimal/moral/better/'done my part' solution. If everyone knew about zipper merging there would be no early mergers (and 'late mergers' don't exist within the context of zipper merging).

Klinky 12y ago
In simulations zipper merging is an optimal solution. In reality, relying on thousands of drivers to properly follow specific directions and be completely aware of their surroundings is a flawed solution. Telling people how to do something efficiently doesn't mean they'll do it that way. People are extremely loose when it comes to following driving rules, e.g. speed, texting, minimum distances, merging, etc..
- ericHosick 12y ago
  I agree that telling anyone to do anything doesn't mean they will do it (change their habits). However, educating people does allow them to make better decisions. Rules themselves aren't always the best/optimal/safest solution either and being loose may be the best solution. For example, in one country in Asia if you are "in-front" of someone you have the right to merge/enter a roadway/get on a free way/change lanes over the person already in the lane. This is just cultural and is so much better than what we have in the west (like the USA). If someone changes lanes and "hits you", it is your fault (unless you were in-front of them). Makes it so much easier to get on the free way, change lanes, etc. as you only have to worry about what is in front of you. Not what is in front of you, behind you, next to you, etc. There are no "blind spots" etc.
justinpaulson 12y ago
Zipper merging is only optimal if traffic is already slowed down dramatically. If traffic is still moving at any kind of speed, then early merge when there is space available will clear congestion faster than everyone driving up to the merge point and hoping that it works out.
- ericHosick 12y ago
  > Zipper merging is only optimal if traffic is already slowed down dramatically. I agree. But note that the idea of Zipper merging is when traffic has already slowed down, not when it is still moving.
- peeters 12y ago
  No, it's provably optimal in flowing traffic as well. However, the "merge point" is variable depending on traffic speed. Obviously when you're going 100 km/h, the ideal merge point is significantly farther back than when it's stop and go. Nobody is saying you should wait until you're 20 feet from the barrier and then swerve into the other lane. But it's not like that's unique to this situation.
  - tedsanders 12y ago
    Zipper merge is synonymous with late merge: https://en.wikipedia.org/wiki/Zipper_merge https://en.wikipedia.org/wiki/Zipper_merge If you move the merge point back, then by definition it becomes an early merge, right? I don't understand your disagreement with what seems like a totally reasonable statement by Justin.
    - cdash 12y ago
      In an early merge there is no real merge point, people just merge wherever they can. As traffic backs up further and further people merge earlier and earlier.
    - peeters 12y ago
      My point is that what constitutes "late" is a function of the speed of traffic. If you define "late" as "the latest point at which you can safely merge without causing negative traffic reactions (e.g. by forcing someone to brake)" then zipper/late merging is better than "moving over as soon as you can", even in light traffic.
- nardi 12y ago
  This is the commonly held belief that is false. It is false because traffic is caused by lack of capacity, not inefficient driving.
slantyyz 12y ago
>> Zipper merging is the optimal solution. People early merge because they think it is the optimal/moral/better/'done my part' solution. It is optimal only when the local driving culture allows it to be. I live in an area where drivers are extremely selfish and the police don't seem to spend a lot of time ticketing bad drivers, so zipper merging typically doesn't work here.
- peeters 12y ago
  > It is optimal only when the local driving culture allows it to be. Yeah, which is why almost the entire article was about the campaigns to change the culture, not about justifying zipper merging as optimal.
  - slantyyz 12y ago
    Fair point, but it's easier to successfully campaign a low density region (i.e, a state with around 7M people like Washington) than a high density metro area (the metro area where I live in has 6M people, so traffic is already a daily nightmare). Those campaigns in Washington and Minnesota just wouldn't fly here. When our metro population was around <=3M, people still zipper merged (in the mid 90s and earlier).
- dionidium 12y ago
  I live in an area where drivers are extremely selfish...so zipper merging typically doesn't work here. This is backwards. Zipper merging doesn't work when drivers attempt to be unselfish by merging early, which results in vigilante lane blockage of those who weren't as considerate. In other words, I'm not being selfish when I block late mergers; I'm enacting justice on other people who were being selfish. The system works when all parties recognize that the best thing for everyone is to merge late.
  - slantyyz 12y ago
    People used to zipper merge where I live... in the 80s. But the metro region I live in is much more dense than it used to be, and combined with the fact that the police don't spend a lot of time enforcing traffic laws, and that the public transportation system has poor coverage, traffic problems have skyrocketed. One of the reasons why people early merge here is that many people don't let mergers in. And one of the reasons why people don't let mergers in is that they regularly get cut off by a second car after letting a merger in. It's a vicious circle. Back in "the day", zipper merging wasn't even an issue. A lot of people early merge here because they'd rather be the one letting people in than hoping to be let in.
MagicWishMonkey 12y ago
The problem is most people don't know how to properly zipper merge, so pretending that everything would be hunky dory as long as people play by a set of rules that you know they aren't likely to play by is an exercise in futility.
- adwf 12y ago
  Don't know why you're being downvoted; I've had too many people deliberately block my merge when I merge late, to ever try it at full speed in the UK :(
  - cdash 12y ago
    People block your merge because they think you cheated and should have merged earlier. If they were educated about zipper merge they would not have the same feeling.
  - danielweber 12y ago
    The solution is more late-mergers: if the other lane were already full, you wouldn't be "cheating" by passing all the cars who are "waiting patiently." You would just be waiting in a line the same as everyone else in your lane and the other lane. I may be overly optimistic, but I think a sign saying "use both lanes and zipper merge at end" would do a lot.
- zo1 12y ago
  Well, quite a lot of traffic is already regulated by people "playing by a set of rules", and that ends up being hunky dory for the most part. I think the reason why this one is the exception is that it's quite feasible for people to "fight back" to those they perceive as abusers. The real problem is accountability. There is none of it(as cops can't be everywhere, all the time) so people end up exercising what little power they do have in order to punish those they view as the abusers.

Klinky 12y ago

In simulations zipper merging is an optimal solution. In reality, relying on thousands of drivers to properly follow specific directions and be completely aware of their surroundings is a flawed solution. Telling people how to do something efficiently doesn't mean they'll do it that way. People are extremely loose when it comes to following driving rules, e.g. speed, texting, minimum distances, merging, etc..

ericHosick 12y ago
I agree that telling anyone to do anything doesn't mean they will do it (change their habits). However, educating people does allow them to make better decisions. Rules themselves aren't always the best/optimal/safest solution either and being loose may be the best solution. For example, in one country in Asia if you are "in-front" of someone you have the right to merge/enter a roadway/get on a free way/change lanes over the person already in the lane. This is just cultural and is so much better than what we have in the west (like the USA). If someone changes lanes and "hits you", it is your fault (unless you were in-front of them). Makes it so much easier to get on the free way, change lanes, etc. as you only have to worry about what is in front of you. Not what is in front of you, behind you, next to you, etc. There are no "blind spots" etc.

justinpaulson 12y ago

Zipper merging is only optimal if traffic is already slowed down dramatically. If traffic is still moving at any kind of speed, then early merge when there is space available will clear congestion faster than everyone driving up to the merge point and hoping that it works out.

ericHosick 12y ago
> Zipper merging is only optimal if traffic is already slowed down dramatically. I agree. But note that the idea of Zipper merging is when traffic has already slowed down, not when it is still moving.
peeters 12y ago
No, it's provably optimal in flowing traffic as well. However, the "merge point" is variable depending on traffic speed. Obviously when you're going 100 km/h, the ideal merge point is significantly farther back than when it's stop and go. Nobody is saying you should wait until you're 20 feet from the barrier and then swerve into the other lane. But it's not like that's unique to this situation.
- tedsanders 12y ago
  Zipper merge is synonymous with late merge: https://en.wikipedia.org/wiki/Zipper_merge https://en.wikipedia.org/wiki/Zipper_merge If you move the merge point back, then by definition it becomes an early merge, right? I don't understand your disagreement with what seems like a totally reasonable statement by Justin.
  - cdash 12y ago
    In an early merge there is no real merge point, people just merge wherever they can. As traffic backs up further and further people merge earlier and earlier.
  - peeters 12y ago
    My point is that what constitutes "late" is a function of the speed of traffic. If you define "late" as "the latest point at which you can safely merge without causing negative traffic reactions (e.g. by forcing someone to brake)" then zipper/late merging is better than "moving over as soon as you can", even in light traffic.
nardi 12y ago
This is the commonly held belief that is false. It is false because traffic is caused by lack of capacity, not inefficient driving.

slantyyz 12y ago

>> Zipper merging is the optimal solution. People early merge because they think it is the optimal/moral/better/'done my part' solution. It is optimal only when the local driving culture allows it to be. I live in an area where drivers are extremely selfish and the police don't seem to spend a lot of time ticketing bad drivers, so zipper merging typically doesn't work here.

peeters 12y ago
> It is optimal only when the local driving culture allows it to be. Yeah, which is why almost the entire article was about the campaigns to change the culture, not about justifying zipper merging as optimal.
- slantyyz 12y ago
  Fair point, but it's easier to successfully campaign a low density region (i.e, a state with around 7M people like Washington) than a high density metro area (the metro area where I live in has 6M people, so traffic is already a daily nightmare). Those campaigns in Washington and Minnesota just wouldn't fly here. When our metro population was around <=3M, people still zipper merged (in the mid 90s and earlier).
dionidium 12y ago
I live in an area where drivers are extremely selfish...so zipper merging typically doesn't work here. This is backwards. Zipper merging doesn't work when drivers attempt to be unselfish by merging early, which results in vigilante lane blockage of those who weren't as considerate. In other words, I'm not being selfish when I block late mergers; I'm enacting justice on other people who were being selfish. The system works when all parties recognize that the best thing for everyone is to merge late.
- slantyyz 12y ago
  People used to zipper merge where I live... in the 80s. But the metro region I live in is much more dense than it used to be, and combined with the fact that the police don't spend a lot of time enforcing traffic laws, and that the public transportation system has poor coverage, traffic problems have skyrocketed. One of the reasons why people early merge here is that many people don't let mergers in. And one of the reasons why people don't let mergers in is that they regularly get cut off by a second car after letting a merger in. It's a vicious circle. Back in "the day", zipper merging wasn't even an issue. A lot of people early merge here because they'd rather be the one letting people in than hoping to be let in.

MagicWishMonkey 12y ago

The problem is most people don't know how to properly zipper merge, so pretending that everything would be hunky dory as long as people play by a set of rules that you know they aren't likely to play by is an exercise in futility.

adwf 12y ago
Don't know why you're being downvoted; I've had too many people deliberately block my merge when I merge late, to ever try it at full speed in the UK :(
- cdash 12y ago
  People block your merge because they think you cheated and should have merged earlier. If they were educated about zipper merge they would not have the same feeling.
- danielweber 12y ago
  The solution is more late-mergers: if the other lane were already full, you wouldn't be "cheating" by passing all the cars who are "waiting patiently." You would just be waiting in a line the same as everyone else in your lane and the other lane. I may be overly optimistic, but I think a sign saying "use both lanes and zipper merge at end" would do a lot.
zo1 12y ago
Well, quite a lot of traffic is already regulated by people "playing by a set of rules", and that ends up being hunky dory for the most part. I think the reason why this one is the exception is that it's quite feasible for people to "fight back" to those they perceive as abusers. The real problem is accountability. There is none of it(as cops can't be everywhere, all the time) so people end up exercising what little power they do have in order to punish those they view as the abusers.