Zipper merge: is it the legal way in MO and KS?

Transportation topics in KC
User avatar
supastudio
Western Auto Lofts
Western Auto Lofts
Posts: 540
Joined: Mon Jan 26, 2004 8:42 am
Location: 39.21°N 94.93°W

Zipper merge: is it the legal way in MO and KS?

Post by supastudio »

I'm a Northlander and all hell breaks loose when any bridge closes down :D In this case the Broadway Bridge. So there is even more traffic on the approach to the Bond Bridge at the Southbound I-29 and I-35 merge. Southbound I-29 near St. Pius X High School turns from two lanes into one. The majority of drivers merge immediately to the right lane as far down as the North Oak intersection.

I've learned from several sources, the correct, proper, and lawful way to merge from two lanes into a single lane is a "Zipper" merge. This is when you use BOTH lanes the entire length and merge at the very end like how the teeth of a zipper interlock. Left and right lane drivers take turns merging into one lane. It seems like it doesn't work this way in the KC Metro. Everyone gets into one lane while the other lane is completely empty. Then you get drivers who intentionally block the empty lane!

So is the Zipper Merge the correct and lawful way? I don't get the logic of people when they are in the slower lane and get upset at all the drivers passing. You were the one who intentional got in the the slower lane early.
brewcrew1000
Hotel President
Hotel President
Posts: 3102
Joined: Fri Feb 11, 2011 10:10 am
Location: Broadway/Gilham according to google maps

Re: Zipper merge: is it the legal way in MO and KS?

Post by brewcrew1000 »

I don't understand that either. My co-worker who I car pool with called my an ahole for going in that empty lane one time. It's like people don't know how to merge here. It seems like Metcalf turning onto 435 East is always empty on one side.
User avatar
beautyfromashes
One Park Place
One Park Place
Posts: 7137
Joined: Mon Mar 21, 2005 11:04 am

Re: Zipper merge: is it the legal way in MO and KS?

Post by beautyfromashes »

Grew up here and always taught that as soon as you see the lane you are in is closing ahead, to merge in. So, I understand the a-hole comment. It says, "My time is more important than yours." Now, it might be because we are a little more generous in our driving then other parts of the country. It's much more likely that someone will let you in where in other places this exchange would be done only when forced at the end of the merge.
AJoD
Valencia Place
Valencia Place
Posts: 1828
Joined: Mon Dec 04, 2006 4:24 pm
Contact:

Re: Zipper merge: is it the legal way in MO and KS?

Post by AJoD »

I don't understand the logic behind giving up that whole lane of extra capacity way before you need to, thought it's kind of nice that others are willing to give it up because it does make my wait time much shorter. Never knew it had a name.
User avatar
chaglang
Bryant Building
Bryant Building
Posts: 4132
Joined: Wed Jan 04, 2012 12:44 pm

Re: Zipper merge: is it the legal way in MO and KS?

Post by chaglang »

beautyfromashes wrote:Grew up here and always taught that as soon as you see the lane you are in is closing ahead, to merge in. So, I understand the a-hole comment. It says, "My time is more important than yours." Now, it might be because we are a little more generous in our driving then other parts of the country. It's much more likely that someone will let you in where in other places this exchange would be done only when forced at the end of the merge.
Ditto. I've never even heard of a zipper merge. I always thought those people were line jumping.

Technical question: what's the advantage of everyone waiting until the end of the lane to merge? Seems like it just moves the traffic jam 500' down the road.
brewcrew1000
Hotel President
Hotel President
Posts: 3102
Joined: Fri Feb 11, 2011 10:10 am
Location: Broadway/Gilham according to google maps

Re: Zipper merge: is it the legal way in MO and KS?

Post by brewcrew1000 »

beautyfromashes wrote:Grew up here and always taught that as soon as you see the lane you are in is closing ahead, to merge in. So, I understand the a-hole comment. It says, "My time is more important than yours." Now, it might be because we are a little more generous in our driving then other parts of the country. It's much more likely that someone will let you in where in other places this exchange would be done only when forced at the end of the merge.
If people aren't going to use that lane or learn how to properly merge, why even build it. A lot of the times I don't even have to wait for someone to let me in because there will be such a huge gap from a lot of the slower drivers in that lane. It also makes sense to use that lane if there is a semi in the other lane because you will always have time to merge.
brewcrew1000
Hotel President
Hotel President
Posts: 3102
Joined: Fri Feb 11, 2011 10:10 am
Location: Broadway/Gilham according to google maps

Re: Zipper merge: is it the legal way in MO and KS?

Post by brewcrew1000 »

Zipper Merging is encouraged in Minnesota and they are starting a new campaign so people know how to do it, even for road construction. It looks like it actually improves congestion

http://www.dot.state.mn.us/zippermerge/
User avatar
chaglang
Bryant Building
Bryant Building
Posts: 4132
Joined: Wed Jan 04, 2012 12:44 pm

Re: Zipper merge: is it the legal way in MO and KS?

Post by chaglang »

MoDOT website:
Your search - "zipper merge" - did not match any documents.
No pages were found containing ""zipper merge"".

Suggestions:
Make sure all words are spelled correctly.
Try different keywords.
Try more general keywords.
User avatar
beautyfromashes
One Park Place
One Park Place
Posts: 7137
Joined: Mon Mar 21, 2005 11:04 am

Re: Zipper merge: is it the legal way in MO and KS?

Post by beautyfromashes »

brewcrew1000 wrote:If people aren't going to use that lane or learn how to properly merge, why even build it. A lot of the times I don't even have to wait for someone to let me in because there will be such a huge gap from a lot of the slower drivers in that lane. It also makes sense to use that lane if there is a semi in the other lane because you will always have time to merge.
Of course, you get some idiot hit you at the 'zipper merge' and you've stalled the entire roadway.
AJoD
Valencia Place
Valencia Place
Posts: 1828
Joined: Mon Dec 04, 2006 4:24 pm
Contact:

Re: Zipper merge: is it the legal way in MO and KS?

Post by AJoD »

chaglang wrote:Technical question: what's the advantage of everyone waiting until the end of the lane to merge? Seems like it just moves the traffic jam 500' down the road.
I've been trying to think of this from a traffic engineering perspective as well, though I'm not an engineer. By maximizing the usage of two-lane driving, you're also shortening the length of the bottleneck. Does it slow down traffic more to have a two-lane road closed to one lane for 50 feet or 2 miles? My thinking is that the longer the closure, the longer the backup, because traffic flow is restricted for a longer line.

They other way of phrasing your scenario is...what's the advantage of moving the merge point up 500'? You're just making everyone go down to one lane for a longer period of time and artificially extending the length of the closure.

The response, I guess, is by encouraging earlier merging, you create a smoother or more efficient merge process. But I'm not really sure this is the case. brewcrew's observations about the natural gaps at the merge point match my experience also. Without having the actual point of lane closure as the merge point, I'm not really sure there's a standard way to tell people when to merge.

I don't think "when you first notice the lane is closed" would work...those signs are often posted a mile or two out. And it would be impossible to enforce, so then you would have "line jumpers." But the other thing that happens when you have people merging before they have to is that you have people in the closed lane slowing down to try to merge way before they need to.

I've given this issue probably an inordinate amount of thought over the past several years. I think I was raised with the line jumper mentality--not in any kind of official way, just seemed generally polite--but it always seemed weird to sit in line and observe the unused road capacity that should in theory, by being used, make the whole process go more quickly. So I started using the open lanes and have found my wait times much reduced, but also want to be a good citizen and make sure science supports my decision. I think it does.
flyingember
Mark Twain Tower
Mark Twain Tower
Posts: 9862
Joined: Tue Jul 17, 2012 7:54 am

Re: Zipper merge: is it the legal way in MO and KS?

Post by flyingember »

the extra length is to provide for a buffer. at 55mph you need to be merging already well before you hit the end of the road, not moving in at the last minute

what really needs to happen is they provide the extra length for emergencies but paint is as an area not to drive on.

in the end, it's less about location and more about speed. merge in to maintain the speed of the rest of the drivers. if you can do this near to last minute, fine. if you need to merge way earlier, do that. but don't force yourself in and create a slowdown for everyone.

zipper merges work in ideal conditions wonderfully add congestion and you get the people who get onto I-35 at Front St but who use the auxilary lane and don't merge in until way on the other side of the river. they're just being jerks.
AJoD
Valencia Place
Valencia Place
Posts: 1828
Joined: Mon Dec 04, 2006 4:24 pm
Contact:

Re: Zipper merge: is it the legal way in MO and KS?

Post by AJoD »

flyingember wrote:the extra length is to provide for a buffer. at 55mph you need to be merging already well before you hit the end of the road, not moving in at the last minute

what really needs to happen is they provide the extra length for emergencies but paint is as an area not to drive on.

in the end, it's less about location and more about speed. merge in to maintain the speed of the rest of the drivers. if you can do this near to last minute, fine. if you need to merge way earlier, do that. but don't force yourself in and create a slowdown for everyone.

zipper merges work in ideal conditions wonderfully add congestion and you get the people who get onto I-35 at Front St but who use the auxilary lane and don't merge in until way on the other side of the river. they're just being jerks.
Maybe we're talking about different things. I'm really thinking mostly about construction situations where one lane of a multilane street is cut off. If traffic is moving along at 55 mph, then there isn't too much of a problem anyway. Usually, things slow to a crawl at the bottleneck, or maybe 20-25 mph. They don't need to paint an area for emergencies, they can accomplish that (and presumably do) with the orange cones used to mark off where you can't drive.

Agree that it is largely about speed and flow--if everyone used both lanes up to the merge point, you wouldn't have a situation where people were zipping by at 50 mph in one lane and 5 mph in the other.
User avatar
supastudio
Western Auto Lofts
Western Auto Lofts
Posts: 540
Joined: Mon Jan 26, 2004 8:42 am
Location: 39.21°N 94.93°W

Re: Zipper merge: is it the legal way in MO and KS?

Post by supastudio »

User avatar
beautyfromashes
One Park Place
One Park Place
Posts: 7137
Joined: Mon Mar 21, 2005 11:04 am

Re: Zipper merge: is it the legal way in MO and KS?

Post by beautyfromashes »

I still think the difference is politeness of the driving community. If you put your turn signal on with an early merge, you will most likely be let in quickly and at full speed instead of waiting til the end and slowing/stopping traffic with a zipper merge. The goal shouldn't be to use the most road but to maintain momentum.
User avatar
beautyfromashes
One Park Place
One Park Place
Posts: 7137
Joined: Mon Mar 21, 2005 11:04 am

Re: Zipper merge: is it the legal way in MO and KS?

Post by beautyfromashes »

.
heatherkay
Alameda Tower
Alameda Tower
Posts: 1424
Joined: Tue Feb 14, 2006 10:39 am
Location: River Market and Rosedale

Re: Zipper merge: is it the legal way in MO and KS?

Post by heatherkay »

The problem is that everyone has to be doing it the same way. Bottlenecks and interruptions happen when someone is doing something that the other drivers don't predict.
loftguy
Bryant Building
Bryant Building
Posts: 3850
Joined: Fri Sep 16, 2005 12:12 pm

Re: Zipper merge: is it the legal way in MO and KS?

Post by loftguy »

beautyfromashes wrote:I still think the difference is politeness of the driving community. If you put your turn signal on with an early merge, you will most likely be let in quickly and at full speed instead of waiting til the end and slowing/stopping traffic with a zipper merge. The goal shouldn't be to use the most road but to maintain momentum.
Politeness, as in "do it my way and we'll be fine?" Politeness should be viewed from another vantage point. There seems to be a passive aggressive nature to drivers in KC. What is wrong with a driver anticipating that the car in the ending lane is going to merge with me and I can allow for that. Instead we seem to anticipate and make sure that the SOB doesn't get in front of us, especially at the last freaking minute!

The physics and mechanics of merging does seem to be especially difficult for Kansas Citians to embrace. The zipper (perfect term) works beautifully, where the populace understands the purpose and it's effectiveness. Drive the 405 in LA and you can see how it works. The folks there have perfected the art/science of communal driving. You maintain momentum AND make full use of the road.
User avatar
beautyfromashes
One Park Place
One Park Place
Posts: 7137
Joined: Mon Mar 21, 2005 11:04 am

Re: Zipper merge: is it the legal way in MO and KS?

Post by beautyfromashes »

Passive agressive? Perhaps. It probably doesn't really make a difference for me. If they would have put the stadiums downtown where they belong I probably would be able to completely opt out of Eisenhowers lovely highway system.
User avatar
GRID
City Hall
City Hall
Posts: 17068
Joined: Mon Sep 15, 2003 12:20 pm
Contact:

Re: Zipper merge: is it the legal way in MO and KS?

Post by GRID »

Zipper merging is how it should be done and how it's typically done in larger cities. The way KC people merge and the way KDOT and local cops want people to merge creates far more problems like aggressive driving, road rage, wasted capacity and dangerous situations of drastic speed differences between lanes.

Just use all the pavement and merge at the end, but in a city where nobody uses turn signals, everybody is on the phone and people can't even merge on to a freeway at a decent speed, the way people merge when lanes drop is par for the course.

I think it comes down to people "trying to be too friendly". Let's get over real early and do the right thing....

In reality they just need to drive and keep things moving smoothly. Using turn signals to change lanes and driving the correct speeds in the correct lanes (speeds being flow of traffic) is much more friendly if you ask me.
brewcrew1000
Hotel President
Hotel President
Posts: 3102
Joined: Fri Feb 11, 2011 10:10 am
Location: Broadway/Gilham according to google maps

Re: Zipper merge: is it the legal way in MO and KS?

Post by brewcrew1000 »

You ever notice Semi's or other drivers sometimes block that construction lane ending making impossible for anyone to merge
Post Reply