this post was submitted on 09 Apr 2024
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Traffic (the book) says most Americans merge into traffic wrong when lanes reduce (from say 3 lanes to 2 lanes for example.)
The right way is waiting until you are at the very end of the lane that's reducing. When that happens up to 60% more cars per hour get through the bottle neck in heavy traffic and accidents resulting in killed or serious injury are reduced by up to 80%.
Bottom line having multiple entry points in a queue with multiple slow down points due to the multiple entry points is the cause of the reduced performance with the way most Americans do it.
But, if I merge as soon as there's space for me I don't have to stress and panic about not having room to get into the other lane or keep driving forward. What do you do if you get to the end of the lane and people aren't letting you in?
The studies were done on highly congested areas. So there wouldn't be an easy way to fit in like I imagine you mean. If it's not congested then I bet it doesn't matter.
As for people not letting you in the study didn't say but I've not found that to be the case. People realize you are at the end of the road and just let you in overall. Not that I've driven everywhere mind you or that a sample size of whatever my experiences are is statistically significant. If it doesn't freak you out too much maybe give it a shot?
Come to NewJersey. It's hit-and-miss, moreso if you duck.
π€£
let yourself in
And you tell other Americans this and they think you're rude. "No, you need to merge as soon as you can, that's rude to drive all the way to the end!"
If traffic is free flowing and an opportunity presents itself then itβs still better to merge earlier.
I'll bet though that when you merge, it is actually slightly disrupting flow as the person behind backs off, and then everyone else slightly adjusts. Now multiply this by more cars merging wherever they damn well feel like? If traffic is flowing and enough gaps exist so nobody has to adjust at all, then the merging literally doesn't matter and it's not the same argument.
Because as the lane is ending, the entire distance from wherever you are to wherever the lane ends is an opportunity to merge without disturbing other traffic. When the lane ends, that moment is now forced, leading to a higher likelihood of the driver(s) behind having to brake more abruptly and/or to an even lower speed.
Both drivers knew the merge end was coming. Unless they're morons. People are morons. That's why this is an argument.
Exactly... Now I'm armed with some data. I look forward to the next interaction.
Does the book mention that the Zipper merge is inherently flawed as it relies on drivers to be far more cooperative than they are?
Yeah. So, like communism, the entire theory breaks down when humans are actually involved.
Yes
Sadly, there are many places in Canada with the same problem. I blame Americans for that, too.
They mostly solved for that with our HOV lanes in Colorado. Some places you can't enter or exit, some places you can enter but not exit, and others you can exit but not enter. Also merging with slow lanes instead of fast lanes. And all monitored by the people who charge for HOV lanes. Adherence looks to be pretty good overall.
I got into a debate about this with about four people a number of years ago. I was unable to convince them that merging at the merge point was more efficient. We all looked at each other like *wtf is wrong with your brain, how do you not understand this? * It's one of those things that so obvious to me but I don't know why - it's just the definition of 'chaos v. efficiency' in my head.
But if we look at the bottle neck point - the point where traffic must be 1 lane - as long as that is moving at the same rate what is the difference if cars merge sooner or later? We're still getting the same number of cars per minute through the 1 lane section of road.
If there is an alternate turnoff that is being blocked by the traffic then yes I can see it. Otherwise I don't see how it makes any difference.
Not riding peoples ass and leaving room would make it smoother too.
Agreed! Though the book says multiple studies find people who leave 2 seconds or more are more likely to rear end someone. While the studies didn't identify why it was hypothesized people who most often leave 2 seconds practice distracted driving. I know the last time I was rear ended my rear dash cam clearly showed he has 200+ feet and didn't look up from his phone until right before he hit me.
At driver school we were taught to leave 3-4 seconds of space and not to look at our fucking toys while we drive.
It's a winning combo. Add in some convictions with loads of embarrassing community service and we change the world a dickhead at a time.
It could also be that the impatient people on the road keep cutting them off, leaving them with less than two seconds between them and an ignorant driver who you will have to prove cut you off or you're at fault for the accident. Of course, that doesn't happen if there's no space in front of you for someone to cut in. So there's my hypothesis.
That's a fair point, when driving my wife's EV it has the fancy cruise control that leaves a good sized gap and people are always taking advantage of that.
Thats probably more of a correlation though. Like, the drivers that leave that much space are probably doing so only because they know they arent paying attention. If they were paying attention, a 2s distance would be safer.
Probably
The people who drive up the shoulder around everyone and then cut in past the end are the real problem.
It's okay to say BMW drivers.
But this is how the Zipper dies, every fucking time.
I mean they aren't increasing the KSI rate, so I disagree with that position. They may be assholes, or maybe they have a loved one dying in the hospital and are trying to get there before they die?
Nah, they just think their time is more valuable then everyone else's. It's the same people who, when a road divides, cruise up the less popular side and then cut across solid lines to get into the more popular side just before the end.
Edit to add - my son's way of not getting frustrated with those people is to assume that they're rushing home to poop.
Is there an illustration of how Americanβs merge? Or how the roads are designed for this?
I read this wrong... Let me see if I can find one.
This gives you an idea. Nothing special about the lane, it's like a lane anywhere else. We just overall merge early and at random distances causing chaos.
The pictures are correct, but they don't show how traffic can back up for miles before the merge point with everybody sitting in just one lane, and some guy who has taken it upon himself to police everyone else's "manners" swerving to block anyone who dares to the the open lane and "cut in line."
I try to be a patient and understanding person, and I hope that person stubs their toe, and right as it's about to heal they stub it again, and on and on until death.
I think there's an assumption in the illustrations.
The merge point can be singular, but not at the very last moment. If the giant flashing light sign that is visible long before the cutoff was considered the merge point, all of the benefits of the premise still hold.
In addition, in the real world the unused lane space is a buffer zone to help the merge to happen without completely stopping, reducing overall traffic.
Where both concepts fall apart is with the "me first" people that use the space to get ahead and cut in, forcing everybody to hit brakes and creates more traffic as nobody is moving, prompting more "me first" to not want to wait and cut in at the end.
one of those being from INDOT (indiana) is funny. That example would break a state traffic law^1 that says you must merge as soon as you pass the lane ends sign
That's interesting.
Ahh okay. Thanks for sharing
If you wait until the very end, there is no guarantee that someone will let you in.
See how deeply entrenched scarcity mentality is in every aspect of our lives.
Zip merging isnβt it?
I didn't know that term until this post
I can see this being accurate. I've seen it where cars are jammed up before the road narrows and free flowing by the time the road actually narrows. The largest road block (pun intended) to this that I see is driver competency, and people letting them in.
I always hear this statistic on how proper zipper merging increases traffic flow rate over no strategy at all, and I simply do not understand how it helps.
They keep pointing to how much of the upstream second lane is "wasted". But like, from a strict perspective of flow rate, is it really?
The bottleneck restricting flow is the reduced speed single lane. Put a vehicle counter on it. Assuming no one wastes time getting through whatever funnel point there is, this flow is consistent. The same number of cars passing at the same speed are getting through regardless of whether the zipper point was a few cars back or ten kilometers back. Unless I can hear an explanation on how zipper merging changes this I remain unconvinced.
Zipper merging still has unquestionable advantages that are obvious to glean, of course.
Putting the merge point as close to the blockage as possible minimizes the time spent in the shared lane. Flow is the same, but the overall time spent in the jam is averaged over all drivers.
That "wasted lane" does not, as far as I can tell, improve flow. But it does improve storage. If cars are piling up at the choke point, utilizing the full extra lane keeps the pilup from backing up as far down the road, reducing potential domino effects through the road system.
Zipper merging is fairer to all vehicles by promoting a FIFO processing order. No one in the closed lane gets screwed, everyone gets through in roughly the order they showed up.
It has lots of advantages, and is clearly the winner, but I fail to see how increased flow is one of them.
Of course, I'm making a lot of assumptions about perfect behavior of drivers, while this statistic is supposedly real-world empirical data. That suggests there are significant inefficiencies in real-world human driving, and that the zipper merge addresses them somehow. But I can't fathom what those are or why zipper merging is relevant to them.