If traffic engineers aren’t the experts on traffic, who is? Genuinely curious.
This is sarcasm right? Engineers get the worst rap out of any profession and you should know this by now. Well I suppose next to meteorologists but I digress.
There’s gotta be a full moon tonight
So who would you consider the traffic experts? B-man and I are eagerly awaiting your response
B-man is right… to a point. If you believe merging early is the cause of a backup, let’s rewrite the math.
If 5lbs of potatoes can only fit into a 5lb bag, does that mean the bag needs to be the same shape? If enough distance is available, you can fit the same capacity into the “thinner” packaging. High traffic areas that have entry/exit ramps every 1/2mi – 1mi will likely kill any plan to prevent backups, but long stretches of road that have 5-10mi between ramps carry this opportunity. Consider 5 cars, all traveling in a loose pack. Sign states a point of merge, 1/2mi, road is clear ahead and entry into the work zone is free of any backup or slowing. 3 are in the lane to remain open, 2 are in the lane coming to an end. Depending on the spacing between the cars on the right, where do the left cars fit in? The 3 cars on the right intend to maintain their position, for they’re in the “proper lane” for traversing the construction area. The 2 on the left can accelerate or decelerate and get in line, there is time. But if nobody changes these ingredients before the point of merge, are they or are they not going to impede their flow, and who’s at fault? By the time they adjust and resume travel, the traffic behind them might have caught up to them and also been forced to slow. A backup has now begun. Was it preventable? It wasn’t a capacity issue so I would say, yes, it was preventable. But who is at fault here?
I’d say… everyone. Measures could have been taken to protect the flow, but none were taken before a capacity issue was created for the limited area remaining for adjustment. As a CDL driver, I see this all the time, where there was space behind me, but they had to be ahead of me, and in the squeeze play, I have had to back out or brake, and then the gap behind me fills in, and it takes a bit for me to get back to speed, allowing even more people to catch the train.
Other things can create backups too, like slower motorists, or people slowing inside the work zone and causing an accordion effect that can affect the influx of traffic. Work areas poorly designed for “turning trucks” are also a backup source. Anything slowing the flow inside the work zone will negatively effect any and all efforts to maintain flow. Merging early and tailgating… will lead to an accordion backup. Waiting until the end and insisting on your turn when there was a 4-car gap between bumpers 1/4mi back, but now there’s a string of three vehicles crowding each other not leaving the room you had seconds ago… will cause a backup. It’s not always one thing or “that driver,” it can be many things so just breathe, and try to do what you can to keep the flow moving. If you get into a backup, zipper. There’s nothing left, regardless of reason. Just like the stoplight example, zipper method clears the area faster. The only time a single lane prevails is if the traffic flow is never impeded in the first place, but that condition is almost always guaranteed to be temporary and strongly absent during certain times of the day.
So who would you consider the traffic experts? B-man and I are eagerly awaiting your response
I dont think there really are any. Yeah, its their job, but they dont do it very well. Case in point. Civil engineers are responsible for designing roadways correct? Well in their infinite wisdom they redesigned Hwy 15 (actually completed it) through St Cloud and managed to put a dozen stop lights on it vs doing overpasses, etc. This was done decades ago, but its an absolute mess. They havent solved the Hwy 23 through St Cloud issue either and it would be simple. Re-route it onto 94 on the West and connect it back on the East Side of St Cloud with a new route. For some dumb reason they are insistent about running these roads through town. Makes zero sense.
Stillakid2
In lighter traffic where one lane can support ALL of the vehicles on the road, merging early will not cause backups.
Picture a garden hose coming off your house and running to the curb. Now picture your next door neighbor’s house with the same.
You both have your valves open and are running at maximum capacity, going full speed pushing out 15 gallons per minute.
Like two lanes of a freeway clipping along with a good amount of cars on the road, combined you’re both dumping 30 gallons per minute down the gutter.
Now you and your next door neighbor have to help water the neighbor across the streets lawn. You find that the two of you only have one hose left, so you and your next door neighbor put a wye on the ends of your hoses and connect them to just one hose to reach across the street.
Some people would think that the end of the single hose should now be able to put out 30 gallons per minute, but it doesn’t work that way…
Each single hose was already near max capacity putting out 15gpm, combining two of them together into a single hose still results in 15gpm across the street. Your house is now letting out 7.5gpm and water is “backing up”.
You and your next door neighbor can try every possibly combination of throttling valves, opening them, closing them, etc, but there’s nothing you can do to get more water across the street other than running a second separate hose.
Now compare it to traffic.
The problem arises when the freeway gets busier. If both lanes are clipping along at 70+ mph with 3-4-5 second following distances and now you expect everyone to come together (doesn’t matter if it’s early or late), now your following distances are down to 1.5-2-2.5 seconds.
Naturally everyone tries to get back to their comfortable level of 3-4-5 seconds. Yes, the traffic will keep flowing, but in order to allow that to happen everyone has let off the gas to let the gaps increase back to normal.
Now the main flow of traffic is going 50-65mph with the majority of people in the lane that isn’t ending, with some “assholes” zipping by in the lane that’s ending a mile or two up the road.
Those people going 50-65mph feel good about merging early and think they did the right thing. You give yourself a pat on the back and curse those who didn’t merge yet.
Little do they know, just behind them the people going 70+ are having to slow down too and are already stacking up. Brake lights are coming on and the accordion effect has started without them even knowing.
Now the open lane has stop-and-go traffic (by their own doing), is solid cars for two miles, and the left lane is clipping along full of “assholes” catching up to the now stop and go traffic at the start of the lane closure.
The zipper merge is the fastest way to keep traffic moving until the volume decreases back to a level where one lane can support all of the traffic at or above posted speeds.
Again, there is nothing anyone can do to prevent traffic in bottlenecks.
It’s no different in nature. Ever see footage of a herd of caribou or buffalo at a river crossing??
Do they slow down and line up single file for 10 miles of stop and go, or stack up at the crossing and zipper merge?
Nature has the most efficient way figured out, why can’t most humans? LOL
Love the example sign were it specifies that zippers are for “during backups”.
Love the example sign were it specifies that zippers are for “during backups”.
That’s what it’s for. If one lane is slowing down (slowing down equates to backing up) compared to the normal flow of traffic, they want you to use both lanes and fill the real estate to begin zipper merging (because it’s more efficient). Two shorter lines are better than one longer line.
There’s no need to zipper merge in free-flowing traffic. You’re just changing lanes whenever you have an opening. It could be two miles before the lane ends, right at the end, or anywhere in-between. Doesn’t matter, doesn’t affect traffic, doesn’t make anyone change speeds.
Love the example sign were it specifies that zippers are for “during backups”.
That’s exactly where all the misunderstanding disagreement entertainment is coming from in this thread.
<div class=”d4p-bbt-quote-title”>Riverrat wrote:</div>
Love the example sign were it specifies that zippers are for “during backups”.That’s exactly where all the
misunderstandingdisagreemententertainment is coming from in this thread.
Exactly. Some people must have never been in real traffic before. 
Love the example sign were it specifies that zippers are for “during backups”.
Now that’s funny.
this thread has removed all the hope I had that the masses will ever figure out the zipper merge
this thread has removed all the hope I had that the masses will ever figure out the zipper merge
There was never a chance that would ever happen. People cant figure out roundabouts and IMO those are simpler to execute than this because there is typically far less traffic.
Well, it is a very complicated process. 
So we all agree that zipper merges will not be necessary on our trip to Red Lake to buy legal reefer unless there is traffic in the specified merge zones. Let’s go.
I explain round abouts like this… when approaching, treat as if you came to a 4 way stop and you can see for a half mile in all directions and there is no vehicles.. just keep rolling along. If there is a vehicle at your left or right, you need to stop until you can safely merge with them. (uh oh… merge again)
If there is a vehicle at your left or right, you need to stop until you can safely merge with them.
All the roundabouts I’ve encountered go from left to right. So you only need to look left for an incoming car. If not, then you enter the roundabout. If there are cars to your right, they yield to you before entering.
The roundabouts here cars can be entering in a multitude of different directions. Some are 2 lanes while others are only 1. I was in the right lane literally the week after I got my truck and some chick in the left lane decided that while we were in the roundabout she was going to just move over. She about crapped her pants when I laid on the horn. No idea WTF she was thinking. I was alongside her.
Shut up!
Now we’re going into roundabout etiquette?
I love IDO.
stillakid2 and B-man are writing SAT questions. People are backing up before doing a zipper merge. Gummi thought there was some type of hope left for the masses and legal reefer is preparing to doom the roundabout. I think I’m starting to follow this.
stillakid2 and B-man are writing SAT questions. People are backing up before doing a zipper merge. Gummi thought there was some type of hope left for the masses and legal reefer is preparing to doom the roundabout. I think I’m starting to follow this.
Sounds like a typical thread on IDO we cover the masses.
<div class=”d4p-bbt-quote-title”>big_g wrote:</div>
If there is a vehicle at your left or right, you need to stop until you can safely merge with them.All the roundabouts I’ve encountered go from left to right. So you only need to look left for an incoming car. If not, then you enter the roundabout. If there are cars to your right, they yield to you before entering.
I only say merge with the vehicle on the right, because “speed matters”… somebody entering in front of you at a snails pace, may have been there first, but you will overtake them at a normal pace
Simple solution is the open lane should not slow down, just keep doing 70mph. 
So we all agree that zipper merges will not be necessary on our trip to Red Lake to buy legal reefer unless there is traffic in the specified merge zones. Let’s go.
Still confused on where else you use the zipper merge unless in a bottle neck due to lane closures. Your theory isn’t making much sense. So that’s why I’m asking.
Shut up!
Now we’re going into roundabout etiquette?I love IDO.
Lol was thinking the same thing!! 
Now it makes sense. No wonder all us fish heads are whacked here lately.
B-man…
I’m done man… LOL! Next thing you know we’ll be entering an analogy competition! LOL
Years ago, Georgia did this thing of taking a 1mi merge warning clear out to a 5mi merge warning, using the last two miles to issue tickets to those who hadn’t fallen in line yet. Mid-rush hour, we floated through the work zones without any slowdowns one day, and the next it would be FUBAR again… mostly because the trooper had someone pulled over. I wouldn’t be surprised if that’s what killed it because in more recent years, I haven’t seen it set up that way. They took the capacity and “lengthened the hose” which opened up the necessary volume. Now, if people don’t behave, can’t help that. I just remember that the lack of backup and easy flowing through the work zone was nice.
They also set up the work zone to be more flow friendly with exit lanes for trucks and extra space for both workers and motorists.
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