Merging on a Highway

[jalapeno_pretzel]

Near where I live, we have two lanes that drop down to one, soon after an overpass for the highway. The right lane drops, and the left lane proceeds. The whole road is backed up at rush hour, both before that bottleneck and after it. Where the road crosses the highway, two lanes open up to make a left turn on the highway. During busy times of day, there are more people wanting to go left than can be accommodated by those two left turn lanes, so the left through lane (which is also the one that will proceed on after the right lane drops) gets backed up with cars not only wanting to go straight and proceed on, but with cars that want to get off the road and onto the highway.

Now, according to the zipper merge idea, cars continuing on past the highway should be using both left and right lanes - even though they know the right lane will soon drop - and merge by taking turns right at the merge point. In addition to making the merge go more smoothly, it keeps cars out of the left lane which would then be adding to the congestion of all the cars that want to move from the left through lane to the left turn lane for the highway.

According to the anti-zippers, every car that wants to proceed onward should get into the left lane as soon as they know that's what they'll be doing. (Which, I might be driving on the section of road with 2 lanes for 5 miles before the lane drops). Why should I get in the left lane that early and be backed up by the traffic that wants to turn left at the highway intersection when there is an open lane beside me? There are 2 lanes for a reason, and they are both intended to be used.

Early merging is entirely appropriate and efficient in light / moderate traffic situations, but when it's heavy traffic, zipper merging is more efficient. Luckily most people around here seem to understand that and are perfectly capable of taking turns at the merge point. I think of it as if there were two lines formed that were going to one bank teller. Once you get up to the head of the line, you take turns with the other line with who goes up.

 

[RedHead0186]

Early merging is entirely appropriate and efficient in light / moderate traffic situations, but when it's heavy traffic, zipper merging is more efficient.

This 100%. If there's no traffic backed up and everything is moving smoothly, then you can merge early and everything keeps moving smoothly. It's when traffic is moving slowly/backed up that zipper merge comes into play, because then you use both lanes of traffic (so backups are shorter than if everyone was backed up in one lane) and people slowly alternate going through the merge point (instead of most people being in one lane and other zooming past the line and cutting in at the last second, which causes people to slam on their brakes and the progression of cars stops.

 

[jalapeno_pretzel]

I think of it as if there were two lines formed that were going to one bank teller. Once you get up to the head of the line, you take turns with the other line with who goes up.

The anti-zippers in this scenario would insist that people should only get in one line, even though two lines had been established, and then try to prevent the other line from taking their turn.

 

[gmi3804]

There's a two-lane intersection near me where the right lane opens after a stretch of parked cars on the right. No one every gets into the right lane, and they line up like cattle to the slaughter to wait to get through the intersection. Those in the know just zip into the right lane and get through the light in practically no time.

I wish more people knew how to drive, and didn't drive like they think they should drive.

Don't even get me started on people in front of me who just about come to a stop on a street when they're turning right into a parking lot.

 

[Moliphino]

I always try to stay aware of the other people driving on the road with me. In the situation the OP describes I would definitely have adjusted my speed or changed lanes. The person trying to merge into my lane almost always has a short pathway to manage that merge. It can be dangerous to drive as if you can pretend that your rights mean you can drive as if no one exists on the road except you.

I think the OP is asking for honest feedback because perhaps s/he is a fairly new driver and doesn't yet understand some of the nuances of driving safely and courteously. It is a kindness to be aware that merging into flowing traffic can be difficult, and working together makes things flow more easily. It can also prevent a really ugly accident. We're all going to be the merge-er and the merge-ee throughout a week of driving. Sometimes you're the windshield, but nobody wants to be the bug.

No, I've been driving this same commute every morning for 10 years now. I'm very familiar. The other person had a very long time to merge, which is why I was surprised to find them right next to me honking when we were reaching the end of the merge lane. There should have been nothing difficult at all about merging in this area in the traffic there was this morning.

 

[gmi3804]

No, I've been driving this same commute every morning for 10 years now. I'm very familiar. The other person had a very long time to merge, which is why I was surprised to find them right next to me honking when we were reaching the end of the merge lane. There should have been nothing difficult at all about merging in this area in the traffic there was this morning.

A highway entrance lane is also an acceleration lane, and should be treated as such, and the driver trying to enter can use the entire lane and merge when it's safe. If they have to decelerate just a bit to let a highway car pass (like they should have done for you), then it's theirs to do.

 

[sam_gordon]

The anti-zippers in this scenario would insist that people should only get in one line, even though two lines had been established, and then try to prevent the other line from taking their turn.

Well, let's be honest, as soon as EVERYONE is the "through" lane (assuming no traffic lights, stop signs, etc), the traffic can move at whatever pace. It doesn't matter whether that happens at the "must merge" point, or a mile+ before.

All the zippering really accomplishes is to line cars up in both lanes, so the distance of the backup is shorter (say 25 cars in two lanes instead of 50 cars in one).

 

[dioxide45]

BTW, in regards to merging for a lane closure, the "traffic science" for that is settled - zipper merging is always best for flow,

It only settles the fact that the length of the backup is shooter. Meaning say one mile vs one and a half miles. It doesn't change the number of cars that need to get through the bottleneck and that is ultimately what will determine how fast cars get through.

 

[gmi3804]

Well, let's be honest, as soon as EVERYONE is the "through" lane (assuming no traffic lights, stop signs, etc), the traffic can move at whatever pace. It doesn't matter whether that happens at the "must merge" point, or a mile+ before.

All the zippering really accomplishes is to line cars up in both lanes, so the distance of the backup is shorter (say 25 cars in two lanes instead of 50 cars in one).

You're not taking into account the distance between cars, and the time it takes for cars to start moving when the car in front starts, and the long line of cars in one lane that potentially affects previous intersections, and.... Well, you get the idea.

 

[sam_gordon]

It only settles the fact that the length of the backup is shooter. Meaning say one mile vs one and a half miles. It doesn't change the number of cars that need to get through the bottleneck and that is ultimately what will determine how fast cars get through.

Just thinking... is zippering "better" because it reduces the amount of time for a given driver?

 

[sam_gordon]

You're not taking into account the distance between cars, and the time it takes for cars to start moving when the car in front starts, and the long line of cars in one lane that potentially affects previous intersections, and.... Well, you get the idea.

But isn't that the case with zippering too? If you have four cars in each lane, Left1 doesn't have to stop. Right1 has to stop while Left1 proceeds. Then L2 has to stop to let R1 proceed. R2 has to stop while L2 proceeds, etc. That's a basic "zipper". So the time it takes for cars to start moving is a wash?

 

[gmi3804]

But isn't that the case with zippering too? If you have four cars in each lane, Left1 doesn't have to stop. Right1 has to stop while Left1 proceeds. Then L2 has to stop to let R1 proceed. R2 has to stop while L2 proceeds, etc. That's a basic "zipper". So the time it takes for cars to start moving is a wash?

This has Universe of Energy vibes:

 

[robinb]

Well, let's be honest, as soon as EVERYONE is the "through" lane (assuming no traffic lights, stop signs, etc), the traffic can move at whatever pace. It doesn't matter whether that happens at the "must merge" point, or a mile+ before.

All the zippering really accomplishes is to line cars up in both lanes, so the distance of the backup is shorter (say 25 cars in two lanes instead of 50 cars in one).

Except the closed lane will eventually zipper anyway and the people who merge early causes them to wait longer. In your instance all 50 people would be in the through lane and some other folks will come along while you're waiting for your turn and zipper anyway. All zipper people will wait for 50 cars and "standard" merging people will either only wait for a car or two (in the closed lane) or more than 50 people in the open lane. PLUS, people don't just put themselves at the END of the line when merging early. Even if they do merge early, they are still budging in front of someone who is already waiting.

 

[sam_gordon]

This has Universe of Energy vibes:

"If they just did the zipper merge, that line wouldn't be so long." Agreed. That's the main "advantage" of the zipper merge IMO.

 

[sam_gordon]

Except the closed lane will eventually zipper anyway and the people who merge early causes them to wait longer. In your instance all 50 people would be in the through lane and some other folks will come along while you're waiting for your turn and zipper anyway. All zipper people will wait for 50 cars and "standard" merging people will either only wait for a car or two (in the closed lane) or more than 50 people in the open lane. PLUS, people don't just put themselves at the END of the line when merging early. Even if they do merge early, they are still budging in front of someone who is already waiting.

Which again, is the human factor. I agree, on paper, in theory, whatever you want to call it, zipper is better. It's when you throw humans (the real world) in that I'm not convinced.

 

[gmi3804]

Which again, is the human factor. I agree, on paper, in theory, whatever you want to call it, zipper is better. It's when you throw humans (the real world) in that I'm not convinced.

Those are the humans who are lining up for a half mile. Let them wait if they want.

 

[Genie+]

Headin out to the highway I got nothin to lose at all
Gonna do it my way take the chance before I fall

 

[georgina]

Since moving to the DC area I have seen a lot of crazy drivers. Reading comments above - zipper merging, yes, absolutely. If you are leaving an open lane, people will take it and move up. Makes sense. I have even adopted the DC way of not getting in a 3 mile long traffic jam in an exit lane at rush hour, there is always someone farther up who is leaving a big space to cut in. And there is always someone (not me) who goes all the way to the exit and just moves over. The other factor (someone mentioned road rage) is that the other driver who gets mad could pull out a gun and shoot you. It happens. Something else I think about especially in certain areas and at night.

 

[ohiomom28]

I always get over into the left lane when approaching an on ramp with cars exiting. If I can't for some reason, I try to speed up so they can merge easier. It's not fun to get to the end of the ramp and nobody will let you in. You can't just stop, so you just hope someone is feeling nice that day or you just kinda force your way in.

 

[Minniesgal]

You technically had right of way

But I would have pulled out to let him in then pulled back in