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Anti-traffic destroys traffic - how to alleviate traffic jam |
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Score
86%
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69 votes,
Feasibility
92%
Originality
92%
Humour
90% |
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Once upon a time, years ago, I was driving through a number of stop/go traffic waves on I-520 at rush hour in Seattle. I decided to try something. On a day when I immediately started hitting the usual 'waves' of stopped traffic, I decided to drive slow. Rather than repeatedly rushing ahead with everyone else, only to come to a halt, I decided to try to drive at the average speed of the traffic. I let a huge gap open up ahead of me, and timed things so I was arriving at the next 'stop-wave' just as the last red brakelights were turning off ahead of me. Sometimes I hit it just right, but sometimes I was too fast or slow. There were so many 'waves' that evening that I had many opportunities to improve my skill as I drove along.
I kept this up for maybe half an hour while approaching the city. Finally I happened to glance at my rearview mirror. There was an interesting sight.
'By driving at the average speed, my car had been "eating" traffic waves'
It was dusk, the headlights were on, and I was going down a long hill to the bridges. I had a view of miles of highway behind me. In the other lane I could see maybe five of the traffic stop-waves. But in the lane behind me, for miles, totally uniform distribution. hadn't realised it, but by driving at the average speed, my car had been 'eating' traffic waves. Everyone ahead of me was caught in the stop/go cycle, while everyone behind me was forced to go at a nice smooth 35mph or so. My single tiny car had erased miles and miles of stop-and-go traffic. Just one single 'lubricant atom' had a profound effect on the turbulent particle flow within the 'tube'.
It's always a good idea to drive without changing speed and without competing with other drivers for bits of headway. But I'd always assumed that the reasons were philosophical rather than practical (ie try to be a calm, nice person.) But my above experience shows differently. A single solitary driver, if they adopt the right driving habits, can actually wipe away some of the frustrating traffic patterns on a highway. That 'nice' non-competitive driver can erase traffic waves. I suspect that the opposite is also true: normal competitive behaviour creates the traffic waves. Suppose we push constantly ahead, change lanes to grab a bit of headway, and always eliminate our forward space in order to prevent other drivers from 'cutting us off'. If tiny traffic waves appear, we will rush ahead and then brake hard, leaving larger waves behind us. Repeated action causes the waves to grow. Ironic that the angry people who drive as fast as possible are unwittingly participating in 'amplifying' the very waves that they hate so much.
More experiments
I rarely commute on 520 where the good traffic waves appear. I started to miss having opportunities to cancel them. However, I soon realised that the same process could be used to affect small traffic jams too. Traffic waves are simply a series of small traffic jams with even spacing. Each little jam is destroyed when a large empty space approaches it from behind. If no new cars are feeding into the jam from behind, yet cars are leaving its front, then the jam is eroding away. If the jam is small enough, or if the empty space is large enough, then the jam can be annihilated entirely by a single car, as I had done with traffic waves.
'Just one single car, if it decelerates while approaching, can bite a massive chunk out of stopped traffic'
Now I remember something from years farther back. When leaving one of those 'rubbernecker slowdowns', I always tried to accelerate like mad. I figured that if everyone did this, then the slowdown would evaporate. Yet this did little good, because the car ahead of me would not accelerate. I could not force the cars ahead of me to stomp on the gas, so I could do nothing to aid the 'evaporation' of the traffic stoppage. Aha! I can control the people behind me if I slow down, but I cannot control the people in front of me when I speed up. Therefore, I can destroy a small traffic stoppage by slowing down as I approach it, but I can do nothing to aid the 'evaporation' at the downstream end of the jam. Accelerating out of the jam does nothing unless everyone would do the same, and there is no way to change everyone's behaviour. But just one single car, if it decelerates while approaching, can bite a massive chunk out of the region of stopped traffic.
On my commute south on I-5 from Everett there is always a right-lane traffic jam at one of the Lynnwood on-ramps. Close-packed cars must crawl along at 2mph for a very long time. Therefore I intentionally approached that jam in the right lane, and started letting a really huge empty space open up ahead of me. By the time I hit the jam, there was maybe 1000ft of empty road ahead of me. Sure enough, my big empty space allowed the front end of the jam to dissolve, while no new cars were feeding it from behind. By the time I arrived, the jam was about half the size it had been. Amazing. This wasn't any little traffic wave, yet just a single driver was able to take a huge bite out of it.
'The nasty, frustrating part of the 0mph jam was changed into a large fuzzy area of reduced speed'
Obviously my actions did more than just reduce the size of the jam. In order to create the empty space, I was temporarily driving about 10 mph below the speed of the heavy traffic. I did this for several minutes, and therefore I was causing a slowdown behind me. After I arrived at the jam, the jam was smaller. When all was said and done, part of the traffic jam had been removed, but it was changed into a mild slowdown and spread backwards upstream over several miles of traffic. Rather than driving at 60mph only to crawl along through a traffic jam for several minutes, everybody was now driving at 50mph for a few minutes before the jam, but then having a much smaller traffic jam to endure. The nasty, frustrating part of the 0mph jam was changed into a large 'fuzzy' area of reduced speed. If I had done it correctly, I could have erased the whole jam, transforming it into many minutes of slightly-slow driving for everyone behind me. (If I could have started 30 miles upstream of the jam, maybe I would have only needed to drive 3mph slower than traffic.)
'When my anti-traffic pulse collided with the traffic of the jam, the two annihilated each other'
Anti-traffic
Here's a general principle I take from the above. Anti-traffic destroys traffic. While I was slightly slowing down to allow a space to gradually open up before me, I was creating a pulse of 'anti-traffic'. When my anti-traffic pulse collided with the 'traffic' of the jam, the two annihilated each other like a positron meeting an electron. Non-linear soliton physics. The soliton waves destroy each other, leaving only a slight smudge behind.
My next thought: if I took several friends along on my experiment, we could have spaced our cars out over many miles. Each of us could have allowed a big blob of anti-traffic to appear, and then the successive impacts of the anti-traffic could have completely erased the traffic jam at the Lynnwood exit. When traffic is sparse, we cannot keep a large space ahead of us, since it is easy to pass a slightly-slow driver. But a number of separate drivers could bring smaller spaces along with them, and any traffic jam would succumb to the barrage of 'anti-traffic'.
Another lesson I learned: plan ahead. Plan way ahead. When stuck in traffic jams, I failed to affect them by 'peeling out' once I'd made my way through the jam. I hoped to make the far end of the jam dissolve. It never worked. But if I had planned way ahead and brought an empty space with me into the jam, I could be using that space to manipulate the jam. Once I get myself packed in with everyone else, I can do nothing. In order to have an effect, I must behave differently before the jam, not while trapped inside it, and not as I leave it.
Ooops! Damn!
While doing all of the above, I once caught myself behaving normally and creating a huge traffic wave. What a hypocrite! Bad habits die hard. Traffic was heavy and I was in the left lane. I had to merge across several lanes in order to get to my exit. I moved right once, but the next lane was packed solid (but moving, not jammed). Nobody would let me in. I drove like this for a long while, then started driving fairly slow in order to drift backwards along the lane. I found a slot and got in, but now I had to merge right once more. Many minutes had passed, and my exit was coming up. The right lane was packed solid, nobody was letting me in. I drove slower and slower, and in a panic I finally forced my way into a small gap, making the guy behind me jam on brakes. After a while I realised that I had just created a huge traffic wave with my behaviour. I had suddenly slowed way down, just like any rubbernecker. But I had an excuse, I had to get to my exit! To make matters worse, I had nearly come to a stop, and brought two lanes to a near-halt too. But it wasn't my fault! Yeah, suuuure.
In stewing about this I realised that everyone has this same problem: the inability to merge in dense traffic. The simple cure is to give up, not merge, and miss the exit. I shouldn't have forced the issue, I should have let my exit go past. But there is a bigger issue here. People should be able to merge. Why was traffic packed so tightly? One obvious reason: to punish the idiots who will jump into any little space. I had always done the same: never let a space appear ahead, or some other driver will immediately fill it in their quest to get a couple of feet of headway. But this sort of driving would also prevent any necessary merges at off-ramps (and at on-ramps too, of course.) By eliminating the space ahead of me, I become part of the impenetrable wall which screws up the traffic at highway ramps.
'A few car-lengths of space ahead of me lets people merge without slowing down and creating traffic waves'
So, if I keep a few car-lengths of space ahead of me, not only can I use it to help vaporise waves and jams, but it also takes away one of the major causes of waves and jams. It eliminates the 'solid wall' of traffic at merge areas, and lets people merge without slowing down and creating traffic waves. Ideally a merge area will act like gear teeth. But if everyone is defending themselves against opportunistic drivers by eliminating all gaps in traffic, then the valid merges cannot take place either, and a traffic jam is created. Sometimes the jam is the fault of people like me who panic at missing their exit. Sometimes the jam is the fault of the huge blinking arrow which blocks one lane of traffic during construction. But the traffic jam is always the fault of those who refuse to let anyone merge ahead of them.
Delusions of grandeur
Seattle suffers from many separate rush-hour traffic jams. Why stop with the Lynnwood I-5 jam? With enough people (maybe with cellphones and GPS units), we could intentionally erase all the traffic jams on all the main Seattle highways!
This is all fantasy at this point. It's probably illegal for several people to 'conspire' to mess with traffic patterns (would we be arrested under a drag-racing law?) And while it is possible for a single driver to have huge effects on traffic, some things can't be done by a few people. For example, suppose I want to eat the I-5 traffic jam south of the city. I would have to go all the way to Tacoma, then drive north. But if I tried driving slightly slow from Tacoma, a space would not open up ahead of me because nothing stops other drivers from passing me. In my experiments, 'anti-traffic' spaces were possible only because traffic was very heavy, and only a very few people had the ambition to leave their lane and move into the empty space.
'Put a row of State Trooper vehicles across the road and have them drive towards the jam at 55 or 50 rather than 70'
Rolling barriers made of State Troopers
OK, so here's how to dissolve a major interstate traffic jam. Start many miles upstream from the jam. Put a row of State Trooper vehicles across the road and have them drive towards the jam. They drive perhaps at 55 or 50 rather than 70 as everyone else had been driving. Nobody can get by them, and so all the traffic behind the State Troopers is moving at 55 or so. In front of them a vast space opens up. After many minutes, the traffic which had been feeding into the traffic jam simply stops arriving. The jam trickles away. Just as the last of it is gone, the row of State troopers arrives, and the jam has been transformed into miles and miles of slightly slow traffic upstream from the old location of the jam.
'This could prevent many fender-benders and road-rage incidents, and erase thousands of man-years of anger and frustration'
The situation is not so simple if extra traffic is entering from numerous on-ramps. The 'rolling barrier' can't affect these extra inputs, and if the major portion of the traffic is from on-ramps, then the 'rolling barrier' idea would be worthless. Ah, but what about 'rubbernecker slowdowns'? A rolling barrier could let the slowdown evaporate, and change it into a wide area of slightly-slow traffic a few miles upstream from the accident. Would the slowdown reform? Would rubberneckers hit the brakes and recreate the 'traffic standing wave'? I dunno. Sometimes 'rubbernecker slowdowns' persist for long after the accident has been cleared. This suggests that the slowdown is somewhat self-perpetuating. If so, then 'erasing' the slowdown might be worthwhile, because once it's erased, it will reform very slowly (or not at all). If the slowdown normally persists for several hours, yet it only takes a half hour to erase it, why not erase it? Over many trials this could prevent many fender-benders and road-rage incidents, and erase thousands of man-years of anger and frustration. Also, the average speed and traffic throughput on the highway might be improved by removing the region of stopped traffic. 'Removing' the jam just spreads it out and does not alter the average long term speed. But the resulting improvements in speed might be more than you'd expect. After all, things are not linear, since those who sit at 0mph for many minutes in a jam cannot compensate by driving at twice the speed limit afterwards. And once a jam is gone, the remaining region of slightly-slowed traffic might disperse fairly rapidly, whereas a traffic jam or stoppage is a different animal and can self-perpetuate once it has formed.
'Take lots of aerial timelapse sequences, to show that we are not just powerless molecules in the flow.'
And finally, it is a cool experiment with enormous and immediate results. Do it for its own sake, take lots of aerial timelapse sequences, use them to show everyone that we are not just powerless molecules in the flow. The behaviour of individual drivers can have vast effects on the highway patterns.
Bill Beaty (e-mail: billb@eskimo.com).
Adapted from William Beaty's web page at www.eskimo.com/~billb/amateur/traffic/trafexp.html
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