Radio transmitter to solve selfish merge

I have written before about the selfish merge which is a tricky problem to solve. One lane vanishes, and the merge brings everybody to a standstill. Selfish drivers zoom up the vanishing lane to the very end and are let in by other drivers there, causing the backup. The selfish strategy is the fastest way through the blockage, yet causes the blockage.

My thinking on Burning Man Exodus made me wonder if we might have a robot signal drivers not with lights but with radio. At the merge point we would place a computer with a radio transmitter, and detectors to measure the speed of traffic in each lane. If traffic flowed at a good speed, it would do nothing. If traffic slowed, signs would light up saying "Tune to and Obey AM 1610. $500 fine for lane changing without clearance."

The robot would be at the merge point, and also have traffic lights marked with lane numbers of names.

The radio robot would then move the lanes through the merge. The key is the robot can tell an entire lane to start moving slowly simultaneously, and to stop simultaneously, even over a longer distance. So it can command the left lane to start moving and the others to remain stopped and not to change lanes. When the left lane has emptied, it can command it to stop and the red light for that lane would go on (clearly visible at the merge point.) A camera could record anybody running the red light or changing lanes into that lane as it is emptying. As it is clearing, the radio voice can tell the next lane to prepare to move, and give it the green light and the verbal command to do so. Lower priority would be given to the lane that is vanishing and those stuck in it -- they were supposed to do a nice zipper merge a mile back, and are only stuck in it because they didn't do so. This means that zooming up in the vanishing lane becomes punished rather than rewarded, and as a result, this jam-clearing approach would be needed far less.

The system would have to be experimented with and tuned for the best results.

There is a problem that there has to be some point where the system starts, after which lane changes are forbidden. There is a risk that a jam could be created there rather than at the physical merge point, by people in the vanishing lane trying to get into to continuing lane. This is the parameter we would tune -- how much punishment can we give the people who wait too long in the vanishing lane before they start creating a jam a bit further up the road? Perhaps no punishment is needed, just equal treatment.

Of course there are two types of merges. Some are temporary, due to construction. Others are permanent. I am primarily aiming at the temporary ones here though it's possible that solutions could be found for permanent merge-jams. However, in permanent merges, drivers get to know the parameters and will try to game them. If we move where the merge is it's hard not to simply move the jam.

There is also the question of the very few cars without radios, and those who can't understand basic instructions in the languages given on the radio. (The instructions can be said in up to 3 languages, I would think.) Such drivers would have to just follow the other cars, which is doable, even if their reaction time will not be as quick. Drivers who can't read the signs already face the risk of violating traffic laws, of course.

I also don't know how much gain you get from everybody being able to stop and start at once on voice command. Obviously moving cars need wider spacing than stopped cars, so you can't actually start everybody at once like a train. Still, I think it should be possible to drain a blockage faster with the combination of coordinated starting and nobody else being allowed to merge into the lane during the period.

It's also possible the voice could tell cars in the vanishing lane to simultaneously enter the continuing lane once it has been cleared, but that requires a way to stop oncoming traffic from entering that lane during that process, and it's easier if all equipment can be placed at the merge point.


This is one of my pet peeves. The so called "selfish merge" is not selfish.

"Selfish" mergers use all of the available pavement until it is necessary to merge. Whether the merging occurs at the end of the useful pavement or 1/2 a mile earlier is irrelevant- it's the same volume of traffic squeezing through the reduced number of lanes.

Where selfish merging really helps traffic is when they take down the cones, signs, and other paraphenalia denoting a work area. The crews start at the front, where they are working, and work their way to the back picking this stuff up. The selfish merger who gets to the front may find the obstruction is already gone and has just helped everyone by removing himself from the traffic backlog.

One day I was on the Beltway around D.C where there were many signs proclaiming "Left lanes closed ahead- all traffic merge right". As a selfish merger, I moved to the far left lane and covered almost two miles at 60 mph while the lemmings in the right lanes were essentially parked. When I got to the construction site, they were done for the day and in the process of taking down the forward signs- both left lanes were 100% open.

Just move to a full smart car.

Do you really want to be talking on the cell phone, miss a sign, and take a $500 fine? Or would rather be chatting on the cell phone, surfing the web, and ignoring your car while it drives you?

I also merge this way and agree with the other comment that this is efficient by using all available pavement.

Also, when I do merge it is usually in front of a truck which is traveling slower than the rest of traffic, further using pavement more efficiently.

While true I make the trip of the people I "cut" possibly slower, I increase the speed of all the people behind me because I get past the jam faster.

Please take as friendly criticism, I like your other ideas and posts on traffic problems.

But there is no "extra pavement." Can you explain to me how, if the vanishing lane went for another 200 feet, your actions would improve the total flow of cars through the checkpoint more than if there weren't the 200 feet? In what way would you be using this "extra pavement" to increase flow out of the chokepoint?

The delay is NOT caused by people merging at the last minute. Cars move slower when they are packed more tightly together. They are packed more tightly together when confined to a single lane as opposed to two lanes. Therefore, the earlier cars merge, the greater distance they travel at a slower speed, and the longer the delay. If EVERYONE just waited until the actual merge point (where one lane ends) and then took turns, both lanes would move equally fast up to the merge point, and you wouldn't have all these peeved nitwits thinking someone in the other lane got ahead of them.

The true capacity of the road is the capacity of the single lane, but at speed. The more speed, the higher the capacity. Slow speeds, like stop and go are the worst capacity. In many cases with a merge, the resulting post-merge highway is not running at capacity. Cars are not packed as densely as they can safely be packed. That demonstrates the problem is not that capacity, but the capacity of the merge-point.

To maximize capacity at the merge point, you need people to merge at speed, not stopping and going.

"In many cases with a merge, the resulting post-merge highway is not running at capacity."

Yet when the single lane opens up again to two or three, it's smooth sailing. The problem is NOT the merge, because the problem persists AFTER the merge, and continues to persist exactly as long as the cause of the problem (greater density of vehicles) persists. The problem disappears immediately when the cause disappears.

Also, with less lanes (take the extreme of one lane), the speed of traffic is limited by the speed of the slowest vehicle. The shorter the one-lane segment, the less number of cars delayed by one slower vehicle.

Imagine you're driving on a three-lane highway, and you see a sign that reads "left and middle lanes closed 50 miles ahead". Now imagine the delays caused when everyone merges into the right lane at that point, and three lanes worth of traffic are compressed into one lane for the next fifty miles. Obviously, it's better to use the available open lanes, otherwise, why have them?


The "Late Merge" Concept
With work zone lane restrictions, it is possible that motorists will be encouraged to use both travel lanes up to the merge point. Known as the "late merge," this concept reduces time spent in a traffic jam.
In maintaining two lanes up to the merge point, there is less driver frustration, and therefore less road rage caused by other motorists who bypass the queue and "butt in line." The "late merge" helps to promote "safer, swifter, and smoother" operation of our highways.

I would like to see the deeper story behind it. They claim the reason is to avoid the road rage against selfish mergers, but I would have to hope they have some other reason.

When I say that the resulting road is not at capacity, I mean that after you pass the merge point, and are on a single lane road, you do not have a traffic jam there. You could put more cars in and still flow. Everybody knows this because they always look forward to getting past the chokepoint and getting an open highway again, even if narrower. The key is how many cars per second can enter the single lane, and that's faster at speed than stopped.

The counter argument would say that the stop and go chokepoint is able to feed the resulting lane at its full capacity. In that case, nothing you can do can make things better in terms of flow, you can only do things to make people happier or make things seem fair, which may be what they are talking about here.

If, on the other hand you are able to feed the resulting lane at more than its capacity, it will also jam up, and you need to choke the chokepoint more. My intuition is that this does not happen, but I would be interested in results.

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