SOME EMAIL ABOUT TRAFFIC JAMS CAUSED BY MERGING LANES Q: What makes you such an expert?! A: Nothing, I am not an expert. I'm just a guy who is fascinated by the "traffic physics" I see during my commutes. I have no reputation to defend, so I have no inhibitions about posting my observations and reasoning, flawed though it might be. All the material on this website is nothing but speculation and "crazy experiments" performed by a total amateur. For info from actual experts, try some of these links: http://www.eskimo.com/~billb/amateur/traffic/traffic1.html#links Date: Wed, 15 Oct 1998 From: Scott Washburn Subject: Entry to Guestbook I just stumbled across this web site, and I must admit, it evoked a number of reactions. First of all, it confirmed what those of us in the business have long contended--that anybody with a driver's license thinks they are a traffic expert. However, I was delighted to see a web site that provided a forum for people to discuss their opinions about traffic and their own personal driving behaviors. Unfortunately, though, I was disappointed to see a web site that was purporting to educate people on traffic flow behavior be based strictly on personal "theories" and absurd personal "experiments". This web site contains a lot of conjecture and opinions about traffic flow and ways to improve it. But, it is very obviously missing solid mathematical and engineering based theories on traffic flow. Now don't get me wrong, I do appreciate a forum for discussion on a topic that impacts many people's lives everyday. However, I am concerned that people that might not know better, which, unfortunately is a lot of the people that have replied to this site, are led to believe that your proposed driving behaviors are what should be adopted by everyone in order to eliminate or minimize traffic congestion. Your personal experiments with speed regulation and headway regulation make for interesting stories, but that is about all. To think that your driving behavior alone in these "experiments" had a significant impact upon the overall level of congestion or the travel time experienced by commuters in this area is ridiculous. Now, it is true that if you could get every driver on the road to employ the exact same rational driving model, traffic congestion would be lessened. But there is the problem, and where your analogy to fluid flow breaks down (which has been explored by several researchers in the past)--every water molecule (i.e., driver) in this case has a different brain, and thus, every driver employs a different driving model. While it would be nice to homogenize driving behaviour (e.g., a surrogate method like vehicle computer control), and thus realize a system optimal traffic flow model, the fact is that people act in their own best self interest, so even the "good samaritan" actions of a few in the traffic stream will be far overwhelmed by the individual self interest actions of the many. Anyway, the fundamental problem with traffic congestion is that there are too many vehicles trying to use the available capacity of the roadway at the same time. And there is very little to nothing your individual games of headway and speed regulation can do to prevent it. As I just mentioned, roadway CAPACITY is one of the fundamental concepts that needs to be understood...and I did not see that mentioned anywhere in your "monograph". When demand exceeds capacity, congestion occurs-- it's as simple as that. Thus, your hypothesis of the wall of state patrol cars pacesetting the traffic is totally absurd. Trust me, this will do nothing more than waste taxpayers' money. Now just think about it, since every possible entry onto the freeway is not controlled (e.g., metering system), it is not possible to prevent demand from exceeding capacity at any particular point along that freeway. Thus congestion could occur anywhere along the freeway where demand exceeds capacity, regardless of where the wall of patrol cars are and what speed they are going. As the demand increases in a freeway section (through increased on-ramp volumes, less smaller off-ramp volumes), people will naturally slow down because of their increased discomfort with decreasing headways as a result of the increasing demand filling in the available capacity of the roadway. Now, I will acknowledge that your attempt to explain a generally complex phenomenon (i.e., shock wave theory) to the lay person is admirable, but you should make sure you thoroughly understand it before trying explain it. Unfortunately this is not the case, as is evidenced by your trying to base your crazy personal traffic flow "theories" upon it. I apoligize if this commentary sounds critically harsh, but I just had to shed some factual light on this subject, based on real mathematical and engineering research. Let me just close by saying this--drive in a manner that you deem rational and leave it at that; no matter how many of your friends you get to drive like you, it just won't make a difference when it comes to changing levels of traffic flow and congestion. Sincerely, Scott Washburn Transportation Engineer Date: Thu, 9 Jul 1998 01:11:29 -0700 (PDT) From: "Michael S. Foster" Subject: Entry to Guestbook ------------------------------------------------------ Aw, c'mon Bill, say you're not serious with your "simple" cure for traffic jams. Surely you just posted this in order to invite people to poke holes in this preposterous piece of illogic. No doubt your head has become muddled while sitting still, frustrated in that jam on the I-5. My guess is that your scheme would result in traffic coming to a complete standstill, but that everyone would be able to change lanes as often as he wishes, as long as he willing to back up. Of course, this is just a guess, but then so are the results of your proposed scenario. Unless, of course, you have the results of an experiment where you have convinced thousands of people to behave in the manner you prescribe. Naturally, you don't have such experimental results, because the only way to modify the driving habits of this many people would be through the use of somewhat draconian coercion. One must always be suspicious of simple solutions to complex problems of human behavior, especially when it involves surrendering rational self-interest to "altruistic" methods whose results are doubtful. In reality, what we have here is a simplified model of capitalism versus socialism and I think the experimental results ar e fairly conclusive when it comes to these two systems. I therefore suggest you put the atruistic traffic on the left and the self-interest traffic on the right on your animated web page. Actually, there are a few experimentally proven methods of reducing traffic jams. I travel a certain section of the 405 freeway, sometimes several times a day, and I noticed a rather dramatic reduction in traffic jamming when they (are you waiting?) RAIS ED THE SPEED LIMIT! Of course, the speed limit was only increased to 65mph from 55, but the difference was and is quite noticeable. Dare I suggest that raising the speed limit to 75mph would really have a salutory effect? Now, I realize that raising speed limits isn't politically correct and won't give you that warm fuzzy altruistic socialist feeling, but it might actually work. This particular rant aside, Science Hobbyist is my very favorite web site and is an example of the internet at its best. I have spent countless hours reading practically everything here and following the endless trail of links leading away to an incredible array of knowledge and information previously unavailable to most people. THANKS, BILL! Michael S. Foster Los Angeles, CA USA - Thursday, July 09, 1998 at 01:11:28 (PDT) ------------------------------------------------------ Date: Thu, 9 Jul 1998 09:39:45 -0700 (PDT) From: William Beaty To: "Michael S. Foster" Subject: Re: Entry to Guestbook: traffic On Thu, 9 Jul 1998, Michael S. Foster wrote: > often as he wishes, as long as he willing to back up. Of course, this > is just a guess, but then so are the results of your proposed scenario. > Unless, of course, you have the results of an experiment where you have > convinced thousands of people to behave in the manner you prescribe. Guess what... I DO have experimental results. Not thousands of people, just one. It turns out that since traffic jams are single-lane events once they appear, therefor sometimes A SINGLE DRIVER can have massive effects on them. I personally have (temporarily) erased small and medium-sized traffic jams at merging-lane areas on numerous occasions. If EVERYONE maintained an extra space ahead of their car, then the merging-lane traffic-jam dynamics would be seriously fouled up, and they could not form. I see one problem in your reasoning. What CAUSES the jam? Is there one car far in the distance which is stopped, and therefor all cars behind it must stop? Nope. These traffic jams are a form of turbulence. Tiny actions by large collections of drivers cause them to appear. If the collections of drivers behave differently, then traffic jams will be affected. I've talked to one traffic dynamicist (see his link on my TRAFFIC WAVES page) and he confirms some of my suspicions. If we can discover which behaviors cause jams, then we can eliminate them simply by informing people about how to take personal action. No legislation is needed. > Naturally, you don't have such experimental results, because the only > way to modify the driving habits of this many people would be through > the use of somewhat draconian coercion. Or by an ad campaign, as was done with recycling and energy conservation in the last 20 years. > One must always be suspicious > of simple solutions to complex problems of human behaviour, especially > when it involves surrendering rational self-interest to "altruistic" > methods whose results are doubtful. Why the hostility? > In reality, what we have here is a > simplified model of capitalism versus socialism and I think the > experimental results are fairly conclusive when it comes to these two > systems. No, all we have is what we have: a suggestion that some types of traffic jams will be affected by small changes in driver behavior. I'm convinced that it only takes a small percentage of drivers to change behavior. I see that one thing is not clear on my webpage: it is not necessary for ALL drivers to adopt the "altruistic" style during merging-lane traffic jams. I've found that if only one driver does so (but maintains a 20-car-length space), then a jam can be reduced or sometimes even eliminated. Note that the "altruistic" style is not needed normally, it's main effect is to alter the traffic-jam physics during heavy traffic conditions where lanes of traffic are merging. After many years of using my car to poke at commuter traffic and considering the results, I have become convinced that only a small proportion of drivers need to adopt the "altruistic" style during a jam, yet it will have profound effects. You're right that no experiment has been done such as my page depicts, with 100% of drivers behaving in the abnormal way shown in the right-hand "gear-teeth merge" animatino. The actual experiment used one car out of about 100: me. > I therefore suggest you put the atruistic traffic on the left > and the self-interest traffic on the right on your animated web page. Why does this need to have ANYTHING to do with politics? Would you refuse to experiment with traffic-holes yourself since traffic-holes are obviously a despicable Socialist invention, while traffic jams are good American Capitalism and we must protect them against the Commies? :) Why instantly involve politics before even trying any experiments? But since you have lept to a political stance, this means that I should go and change my page to eliminate "altruist" and "self-interest", since it will probably make others leap into political-think and so refuse to actually TRY my suggestion. > Actually, there are a few experimentally proven methods of reducing > traffic jams. I travel a certain section of the 405 freeway, sometimes > several times a day, and I noticed a rather dramatic reduction in > traffic jamming when they (are you waiting?) RAISED THE SPEED LIMIT! Of > course, the speed limit was only increased to 65mph from 55, but the > difference was and is quite noticeable. Dare I suggest that raising the > speed limit to 75mph would really have a salutory effect? It may. Since traffic waves and stoppages are caused by collective behavior, then even tiny changes in the average behavior may have drastic effects on them. > Now, I > realize that raising speed limits isn't politically correct and won't > give you that warm fuzzy altruistic socialist feeling, but it might > actually work. Altruism is socialist? Only if it is forced by legislation. Actually, I think there should be no speed limits at all. Look at Europe and the Autobahn, it is experimental proof that such a thing is feasible. It has always amazed me that the "land of the free" has no Autobahn. If you can figure out a way to see traffic-holes as capitalistic (hey: tiny individuals who can beat the hell out of a collective?), then give them a try yourself. I've cancelled enormous numbers of "traffic waves" on 520 during rush hour. (Check out the email discussion on my TRAFFIC WAVES site.) Anyway, glad you like my stuff! ((((((((((((((((((((( ( ( ( ( (O) ) ) ) ) ))))))))))))))))))))) William J. Beaty SCIENCE HOBBYIST website billb@eskimo.com www.eskimo.com/~billb EE/programmer/sci-exhibits science projects, tesla, weird science Seattle, WA 206-762-3818 freenrg-L taoshum-L vortex-L webhead-L Subject: Re: TRAFFIC JAM CURE From: mac@mac.net (One Ton) Date: 1998/07/08 Newsgroups: seattle.general Buy a car with a rear view mirror and you might see things differently....... ;>) Mike Subject: Re: TRAFFIC JAM CURE From: billb@eskimo.com Date: 1998/07/09 Newsgroups: seattle.general > Buy a car with a rear view mirror and you might see things > differently....... ;>) Hmmm? What's your meaning? In my traffic diagrams, wide gaps allow a high-speed merge, while narrow gaps prevent merging and cause a traffic jam. If this idea is wrong, I'd like to hear the details. Actually, all attempts at "amateur traffic engineering" must be based on the fact that drivers have very little effect on the traffic ahead of them, yet they can exert significant control on the traffic which follows behind. If I were to "rubberneck" and completely halt my car for no reason, I could leave a long-term traffic jam behind me. On the other hand, if I approach a traffic jam at a slow speed, a large gap will open up ahead of me. The gap allows the traffic jam to trickle away but with no new cars piling up behind it, and when I finally arrive, part of the jam has been "eaten" and converted into a region of slower traffic behind me. In this way a single driver can take a bite out of a traffic stoppage. If the stoppage was small, then it might be erased entirely, and converted into a wide region of slightly slower traffic. Average speed does not stay the same: The stoppage was a nonlinear effect, and removing it causes increased overall speed. But the "road rage" people will punish me! I'd better buy armament! ((((((((((((((((((((( ( ( ( ( (O) ) ) ) ) ))))))))))))))))))))) William J. Beaty SCIENCE HOBBYIST website billb@eskimo.com http://www.eskimo.com/~billb EE/programmer/sci-exhibits science projects, tesla, weird science Seattle, WA 206-762-3818 freenrg-L taoshum-L vortex-L webhead-L From: bitbucket@wolfenet.com (Sonya) To: bbeaty@microscan.com Subject: Re: TRAFFIC JAM CURE Newsgroups: seattle.general In article <6o36e2$3ll$1@nnrp1.dejanews.com>, bbeaty@microscan.com wrote: > Actually, all attempts at "amateur traffic engineering" must be based on > the fact that drivers have very little effect on the traffic ahead of > them, yet they can exert significant control on the traffic which > follows behind. If I were to "rubberneck" and completely halt my car > for no reason, I could leave a long-term traffic jam behind me. On the > other hand, if I approach a traffic jam at a slow speed, then a large > gap will open up ahead of me. The gap allows the traffic jam to trickle > away but with no new cars piling up behind it, and when I finally > arrive, part of the jam has been "eaten" and converted into a region of > slower traffic behind me. In this way a single driver can take a bite > out of a traffic stoppage. If the stoppage was small, then it might be > erased entirely, and converted into a wide region of slightly slower > traffic. Average traffic speed does not stay the same: The stoppage was > a nonlinear effect, and removing it causes increased overall speed. This absolutely DOES work. In fact, I think you should buy the domain name "www.trafficwaves.com" and I will personally volunteer to create and post signs with the URL on every major freeway in the state. Since reading one of the earlier posts about traffic waves, I've been trying it out in traffic, and it's amazing. True, the hardest part is ignoring the irritation of drivers behind you, but I just tilt up my rear view mirror and think of something else. They seem to think that the two feet they gain by being right on your tail will get them there faster. Please keep posting this now and then - it should only take a small percentage of drivers to noticably change the traffic situation in this state. Sonya Please change "bitbucket" to "elysium" in my address to reply by e-mail. Subject: Re: TRAFFIC JAM CURE From: joearmy@wolfenet.com (Steven Spencer) Date: 1998/07/14 Newsgroups: seattle.general I've been doing the same thing and I've got to agree with the previous two posters. This method of 'curing' traffic waves is amazing!! And Sonya, just turn your music up extra loud to drown out the sounds of the idiots who tailgate you when the honk. That's what I do! And even more incredible is that my stress level while driving has dropped tremendously. A large part of my frustrations have been the rubber-neckers. Now I just don't worry about 'em as much. Date: Fri, 17 Jul 1998 09:14:43 -0500 From: Bob Liepa To: bbeaty@microscan.com Subject: Traffic Merges In cases where the number of lanes decreases, it is incorrect to state that drivers who wait until the last second to merge are "greedy". It is also incorrect to state that drivers who merge early show foresight and consideration. The optimal strategy for the entire group of drivers is to keep all the lanes filled and to merge at the single point where the disappearing lane actually ends. In fact, anyone who merges "early" is just contributing to the problem. There are probably two main reasons for merging early. One is that drivers (mistakenly) think they are being courteous or socially responsible. The other is that some drivers feel that if they wait to long to merge, they might not be let in. In fact, it's always possible to merge. If the disappearing lane is empty, one should therefore have no reservations about using it until the end. This is different, however, from "jumping the queue" by using an empty acceleration lane from an entry ramp. In that case, using that lane would require a driver to "unmerge" from traffic and then "re-merge" at a later time. This creates an extra merge and is therefore not optimal for the entire group of drivers. Of course, if the driver is legitimately entering the highway at that point, he or she should take advantage of that lane until it ends. It's a one-time privilege for newcomers to the traffic jam. Bob Liepa Senior Vice President Research Dimensions Ltd. 30 Soudan Avenue, 6th Floor Toronto, Ontario M4S 1V6 Tel: 416-486-6161 Fax: 416-486-6162 Date: Sat, 7 Aug 1999 11:25:08 -0700 (PDT) From: William Beaty To: Chad Spencer Subject: Re: Entry to Traffic Waves On Sat, 7 Aug 1999, Chad Spencer wrote: > Well you've solved the traffic problem in front of you, but you've > totally neglected the situation behind you. Consider this: You're on > the freeway, and you spot a traffic jam a mile or so up the road. You > slow down to create the huge space in front of you, and by the time you > get to the jam it is gone. BUT, while you were slowing down the traffic > behind you, more cars were entering from the on-ramps at a normal rate. You bring up a good point. I mention this problem in a couple of places, but I guess I have to state the solution more specifically. Yes, it is impossible for me to remove cars from the road. All I can do is transfer the patches of high-density traffic from one place to another. I can also take a small, dense region and spread it out into a large, less-dense region. In a highway with no entrances or exits, wouldn't this be pointless? No, not always, because I can erase "traffic waves" and "shock wave" stoppages. A traffic wave is nothing but patches of slowdown, and by moving them around, I can create totally smooth traffic. And a total stoppage can be changed into a large zone of slow traffic. There is a second place where I can have an impact. When a slowdown-zone becomes stuck at a merge-zone, a true bottleneck appears. My little animations depict this phenomeonon. If I can grab that slowdown and move it far upstream, so that cars at the merge zone can merge at high speed like "gear teeth" or a "zipper", then I have changed the capacity of the highway at that point. It is a nonlinear effect. If it wasn't, then there would be no good reason to mess with traffic there. Is it possible to make traffic worse? Certainly. I don't entirely understand your message, but I think you might be discussing a situation where there are a number of merge-zone traffic jams in a row. If I try to "cure" the last one in line (the most-forward downstream jam), then I make the jam worse at the upstream ones. Yes, this is correct. If most of the traffic is coming from entrance ramps, and not from the main highway, then one car can safely manipulate only the first jam, the most-upstream jam. If I try to cure the downstream ones, then I dump a slowdown into the upstream ones and make them worse (or possible trigger a new traffic jam.) Another way to say it: a row of small traffic jams will interact with each other. Each one is a nonlinear "switchable" phenomenon all on its own. Together, they are like a living thing and their actions will be very unpredictable. If I try to manipulate them, they might "explode" into a really horrible mess. In my commutes I've encountered big jams at single exit ramps, where there are no other exit ramps anywhere around. I fortunately don't drive in a place where those "living creature" collective multi-ramp jams exist, so I've never had to think about them. > I'll give you a big hand for effort, but in all of the thought you put > into eliminating the traffic in front of you, you completely forgot > about what was going on behind you. Of course not. It is impossible for me to affect the traffic ahead of me. All my thinking is based on this fact. I can only affect the traffic behind me, so that's the first thing I think about. See http://www.amasci.com/amateur/traffic/seatraf.html#three How can I manipulate the traffic behind me? Since I cannot drive faster in congested traffic, I can only drive slower. If I drive slower INSIDE a congested zone, then I make the traffic worse. Therefor I must create my "antitraffic" hole while I'm in a lightly congested zone, and not do this in the middle of a bunch of on-ramp merge zones! ((((((((((((((((((((( ( ( ( ( (O) ) ) ) ) ))))))))))))))))))))) William J. Beaty SCIENCE HOBBYIST website billb@eskimo.com http://www.amasci.com EE/programmer/sci-exhibits science projects, tesla, weird science Seattle, WA 206-762-3818 freenrg-L taoshum-L vortex-L webhead-L