Washington, Minnesota officially endorse a “safer, faster” traffic merge • Hacker News Board

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#161

Post by cdash » Fri, Jul 25, 2014, 6:54 AM UTC

tedsanders wrote: post #134

peeters wrote: post #76

Earlier quoted context omitted.

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.

Zipper merge is synonymous with late 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.

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.

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#162

Post by nhaehnle » Fri, Jul 25, 2014, 7:07 AM UTC

chrisseaton wrote: post #127

ericcumbee wrote: post #98

Earlier quoted context omitted.

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.

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#163

Post by cdash » Fri, Jul 25, 2014, 7:14 AM UTC

blahedo wrote: post #141

A lot of people and a lot of articles discuss resistance to this as a matter of misguided "politeness", and a LOT of the support for it carries a tone of smugness---there is definitely a weirdly emotional component to this. But here's the fairly objective thing I want to know: the people who have been (very negatively!) described as "early merge vigilantes" generally operate by staying in the lane that goes away but…

I think you are misunderstanding what is being called "early merge vigilantes". They are people who merge early and then don't let people who didn't merge early like them in because they are trying to punish them for "cheating".

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#164

Post by nhaehnle » Fri, Jul 25, 2014, 7:16 AM UTC

tedsanders wrote: post #110

dusing wrote: post #11

Earlier quoted context omitted.

I live in the Twin Cities and "Minnesota nice" means merging incredibly early when a lane is posted as closed. As a transplant I can always count on getting and extra 1/2 - 1 mile ahead by staying in the closed lane. It is getting better, but still 40% of the time the car at the end of the zipper merge is NOT happy to see you, and thinks they are letting you in. Signage is helping at the big construction areas.

The whole point of zipper merging is to minimize speed differences between lanes for maximum efficiency and maximum safety. The proper way to execute a late zipper merge is to match speeds and merge at the end. You are not correctly zipper merging if you are passing other cars before merging at the end.

dusing is probably talking about the (rather common in some places) situation where one lane has half a kilometer of slow-to-standing vehicles, while the other lane is entirely free.

In this situation, of course you're going to pass those other cars (please do so slowly and carefully if you pass them on the right). It would be ridiculous to slow to a standstill with half a kilometer of empty road ahead of you.

When zipper merging works correctly, you usually cannot pass cars in the other lane, because traffic automatically flows in the right way. So in a sense you are right that if you pass cars in the other lane, someone is doing the merging wrong. That someone are the people in the crowded lane, however, not the one of who is passing them in the empty lane.

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#165

Post by a_e_k » Fri, Jul 25, 2014, 7:20 AM UTC

DrewRWx wrote: post #156

a_e_k wrote: post #123

Earlier quoted context omitted.

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.

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#166

Post by TeMPOraL » Fri, Jul 25, 2014, 7:20 AM UTC

dubfan wrote: post #91

nardi wrote: post #77

Earlier quoted context omitted.

This is the commonly held belief that is false. It is false because traffic is caused by lack of capacity, not inefficient driving.

Road capacity and driver efficiency are related. Roads have a theoretical capacity that is rarely reached due to inefficiencies in driver's habits.

Exactly. Drivers as a class tend to think that they are smarter than everyone else, particularly the transportation departments, and think that e.g. speed limits are something you need to be above, otherwise you're an annoying driver. It's a huge cultural problem and one of the main reason I can't wait to see drivers displaced by self-driving cars.

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#167

Post by Cthulhu_ » Fri, Jul 25, 2014, 7:40 AM UTC

I've recently sold my car (a crappy Opel) and replaced it with a motorcycle, and my behavior in traffic has definitely changed re: merging. The other day there was a mile-long queue in front of a highway exit, traffic was up on the hard shoulder or whatever the term is. If I were still in my car, I would've been polite and just queued up - would probably cost me 15 minutes to get to the exit and further on.

Now though, I did full D-bag and just drove past most of the line. At the exit, the queue started breaking up, leaving plenty of room for me to merge into.

Actually if everyone took a motorcycle instead of their car, most of these problems would be gone. But that's probably a silly argument.

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#168

Post by tedsanders » Fri, Jul 25, 2014, 7:42 AM UTC

nhaehnle wrote: post #164

tedsanders wrote: post #110

Earlier quoted context omitted.

The whole point of zipper merging is to minimize speed differences between lanes for maximum efficiency and maximum safety. The proper way to execute a late zipper merge is to match speeds and merge at the end. You are not correctly zipper merging if you are passing other cars before merging at the end.

dusing is probably talking about the (rather common in some places) situation where one lane has half a kilometer of slow-to-standing vehicles, while the other lane is entirely free. In this situation, of course you're going to pass those other cars (please do so slowly and carefully if you pass them on the right). It would be ridiculous to slow to a standstill with half a kilometer of empty road ahead of you. When z…

Thank you for your charitable interpretation of my comment, but in fact I don't think it is ridiculous to drive slowly in the right lane. I really do think that's the correct strategy.

Even if the second lane is free, it's safer and more efficient to match speeds with the first lane. And shouldn't we take actions that maximize safety and efficiency? Note that there is no global gain from speeding down the right lane, since the bottleneck is what controls the flow.

I suspect many of you will disagree with me, so let me address some possible concerns.

Is it safer? Yes. Generally driving is safer when all vehicles are moving at similar speeds. Relative speeds being low mean that there's plenty of time to react to danger. It's also safer because other drivers are more predictable when going at a single speed.

Is it more efficient? Yes. The bottleneck is constraining the flow, so gains before the bottleneck end up being useless. The important thing is to make sure that traffic is entering the bottleneck at a fast, consistent speed. Predictable and uncontested merges are the best way to stop the traffic lane from slowing. Going at the speed of the left lane offers two benefits here. First, it's easier and more predictable to merge when you travel at the same speed as other traffic. Second, if you travel at the same speed as other drivers, they won't get annoyed at you and attempt block you out (to everyone's detriment).

Is it weird? Yes. Driving below the speed limit with space in front of you is an odd thing to do. But in this case, you're matching the speed of traffic and there's no global opportunity cost because the bottleneck ahead is the constraint, not your speed. It's weird, but it makes sense.

The reason that the zipper merge is recommended by so many travel departments is not because it's straight-up more efficient than other merging strategies - it's because it's more robust to defection.

But just because it is robust to defection, that doesn't mean the optimal strategy is to defect.

For those of you who disagree, why? Could you point out where you feel my logic fell short?

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#169

Post by aluhut » Fri, Jul 25, 2014, 7:52 AM UTC

molf wrote: post #9

I'm surprised this is written like zipper merging is some kind of recently discovered secret. Zipper merging (or weaving) has been standard practice in parts of Europe for 20 years (maybe longer – I can't really remember anything else). Since March 2014 it is even mandatory in Belgium, and anyone merging early may risk a €55 fine [1]. It has been repeatedly advocated and promoted by various governments in Europe [2]…

I wish it would work...they teach it since decades in Germany and you still see people not doing it right or worse: people complaining that you drive up to the end. People not letting you in at the end and so on...

I still try it every time because most of the times, it just saves me a lot of time.

I've never seen/heard of people being fined for not doing it or preventing people to merge.

Re: Washington, Minnesota officially endorse a “safer, faster” traffic merge

#170

Post by Titanbase » Fri, Jul 25, 2014, 8:12 AM UTC

notacoward wrote: post #27

Zipper merging works great as long as everyone on both sides is willing to alternate (or if strong enforcement requires them to do so). Otherwise, letting "late mergers" scream past fifty "early mergers" often creates a situation worse than simple early merge. There's plenty of blame to go around. * The vast majority of the people blasting down the late-merge lane clearly have no interest in alternating or merging in…

In reality, the early mergers are the problem.

They are screwing up the system by merging too early, then adding insult to injury, getting all bent out of shape about people who aren't 'early mergers'.

So first they create the problem, then they get upset when someone does it the right way. Classic!