Yeah, that’s the big asterisk on the “zipper merging is more efficient” premise. It assumes that things are already bottlenecked. If you have the space to merge early without slowing down, you do that. People trying to force their way in at the last minute (when they didn’t have to) is one of the things that triggers the bottleneck in the first place.
K but people don’t tend to complain about those driving down the empty lane if there is no bottle neck.
Obviously if you’re racing down to cut someone off, that’s just as rude as any unsafe merge, but thats not unique to zipper merging, so is it relevant?
Zipper merge is always the most efficient if people dont prevent merges, regardless of road conditions. It means both open lanes are used to move cars forward until the last moment when they cannot. “Move over early” means less throughput in the system, no matter “how open” one lane is at some point.
By blocking merges, you causes braking, which is what causes traffic. You framing people driving efficiently to prevent traffic as “people trying to force their way in last minute” means its you creating traffic, not them.
You’re arguing from a sense of moral suppority, I.e “I got in line early, you should have to,” not from a sense of efficently moving cars down a road.
Agreed on never being the one blocking merges, but for the merging party, “if people don’t prevent merges” is such a huge caveat that I think attempting a zipper merge at a lane ending at any appreciable speed is impractical at best and downright dangerous at worst.
If everyone is traveling slow already, failing to merge quickly at the lane ending isn’t a huge threat to safety and just a slight hit to efficiency. Most merges I’ve experienced are probably in the 40 to 80 mph range though. In that case, you absolutely do want to take the first decent merging opportunity you can, because waiting to do it until the lane ending can have huge safety and/or efficiency consequences if another good merging opportunity doesn’t open up at speed.
Also, I’m pretty sure zipper merging was mentioned zero times in driving lessons and tests where I’m from, so you should basically just assume other drivers don’t even have it as a concept. If you’re from somewhere where more people practice it regularly, then I can see why you are more encouraged to enforce it as a baseline.
It’s rare, but I think they’re referring to when it’s open enough and running at optimal speeds. It happened the other day on a side street during an off hour, the free lane couldn’t cut to the front without going like 70mph in a 40mph zone.
And it shows exactly what I’m talking about. When people are more interested in filling lanes than merging efficiently when one is disappearing, they reduce the throughput of traffic over all.
I’ll merge early but also try to go a bit slower than the person in front of me to open a gap which allows me to absorb some of the traffic wave (where flow alternatively speeds up and slows down from people trying to get up to speed only to have to slam on the brakes because some car ahead wasn’t going fast enough to maintain that), as well as leave space for others to merge at speed.
Though I sometimes close the gap if I notice people pulling into the right lane to try to skip the line.
Depends. If there’s lots of traffic, yes. If it’s sparse enough that you can merge without slowing people down too much, just do it early.
Yeah, that’s the big asterisk on the “zipper merging is more efficient” premise. It assumes that things are already bottlenecked. If you have the space to merge early without slowing down, you do that. People trying to force their way in at the last minute (when they didn’t have to) is one of the things that triggers the bottleneck in the first place.
K but people don’t tend to complain about those driving down the empty lane if there is no bottle neck.
Obviously if you’re racing down to cut someone off, that’s just as rude as any unsafe merge, but thats not unique to zipper merging, so is it relevant?
Zipper merge is always the most efficient if people dont prevent merges, regardless of road conditions. It means both open lanes are used to move cars forward until the last moment when they cannot. “Move over early” means less throughput in the system, no matter “how open” one lane is at some point.
By blocking merges, you causes braking, which is what causes traffic. You framing people driving efficiently to prevent traffic as “people trying to force their way in last minute” means its you creating traffic, not them.
You’re arguing from a sense of moral suppority, I.e “I got in line early, you should have to,” not from a sense of efficently moving cars down a road.
Agreed on never being the one blocking merges, but for the merging party, “if people don’t prevent merges” is such a huge caveat that I think attempting a zipper merge at a lane ending at any appreciable speed is impractical at best and downright dangerous at worst.
If everyone is traveling slow already, failing to merge quickly at the lane ending isn’t a huge threat to safety and just a slight hit to efficiency. Most merges I’ve experienced are probably in the 40 to 80 mph range though. In that case, you absolutely do want to take the first decent merging opportunity you can, because waiting to do it until the lane ending can have huge safety and/or efficiency consequences if another good merging opportunity doesn’t open up at speed.
Also, I’m pretty sure zipper merging was mentioned zero times in driving lessons and tests where I’m from, so you should basically just assume other drivers don’t even have it as a concept. If you’re from somewhere where more people practice it regularly, then I can see why you are more encouraged to enforce it as a baseline.
This will only be done right by AI.
It’s rare, but I think they’re referring to when it’s open enough and running at optimal speeds. It happened the other day on a side street during an off hour, the free lane couldn’t cut to the front without going like 70mph in a 40mph zone.
Of course a muscle car did just that, but still.
No.
Throughput is determined by number of through-lanes and the speed at which traffic is moving. Period. Completely.
Filling the merge lane when traffic is already slow does nothing but drive density up, which slows traffic further.
Sure, YOU might save some time by passing a bunch of cars, but it DOES NOT IMPROVE THROUGHPUT.
Zipper merging is about NOT having an area of abrupt speed change. It is not about using up a lane that is going away. Period. Ever.
It’s the same as an on-ramp: If you’re speeding up just to slam on your brakes to merge, that’s not zipper merging!
Someone made a simulator for these scenarios where you can adjust on driver behaviour and see metrics in what is most efficient.
https://www.traffic-simulation.de/
And it shows exactly what I’m talking about. When people are more interested in filling lanes than merging efficiently when one is disappearing, they reduce the throughput of traffic over all.
I’ll merge early but also try to go a bit slower than the person in front of me to open a gap which allows me to absorb some of the traffic wave (where flow alternatively speeds up and slows down from people trying to get up to speed only to have to slam on the brakes because some car ahead wasn’t going fast enough to maintain that), as well as leave space for others to merge at speed.
Though I sometimes close the gap if I notice people pulling into the right lane to try to skip the line.
If it’s that sparse then the situation in the meme is a non-issue
…until people make it an issue by speeding up and cutting people off, causing it to bottleneck
Correct