Supercomputers Used to Study Urban Traffic 113
itachi writes "This is a great article in the [Washington] Post about using supercomputers at Los Alamos and physics modeling to study traffic jams. The basic notion is that light traffic is a fluid state, with cars instead of particles, and traffic jams are sort of equivalent to a change of state to a solid. There is even talk of trying to simulate traffic along the east coast from DC to Boston, using a computer along the lines of Blue Mountain. "
Mathematics of traffic flow: URLs and demos (Score:4)
To give you an idea of the scale of the modelling problem itself, there are commercial companies selling software in the $500-1500 range (and up, no doubt) for analyzing these problems. Here's an example: http://www.trafficware.com [trafficware.com]. In addition to demos (sadly, only for Windoze) it also contains many links and information on the mathematics behind traffic modelling.
All I can say is that I modified my driving habits after reading these sites, not out of any altruistic desire to improve traffic flow, but because it was fascinating to experiment with the theory that even a single car in a large traffic jam can act as an "antiparticle" and singlehandedly improve flow in two or three lanes. The improvement in traffic flow behind me (and my reduced blood pressure as a driver) was just a happy side effect.
Re:How much of this is really necessary? (Score:2)
I agree that the bad driver factor is an important consideration. Take I-280 between San Francisco and San Jose. Running primarly though the 'green belt', it is usually lightly travelled.
The average speed in the left lane is usually 75-80 MPH, that is except for the people who just feel like driving 60-65 MPH. Nobody really wants to slow down for these people, so they swerve right a couple lanes to get around the back up.
To make matters worse, there seems to be a large portion of the population that can't turn on their turn signal without hitting their brakes, leading tailgating drivers to slam on their brakes harder. People start cutting other people off and acting generally stupid just to try to get past the one or two retards blocking traffic.
Pretty soon, traffic speed is down to about 45 MPH - same amount of traffic, just one or two blockages thrown in.
(Note, most Americans might think it wierd to bitch that you can't drive 75 MPH all the time, but that's California.)
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One more thing: merging onto freeways (Score:2)
Another big problem, especially here in Portland, Oregon, has to do both with driver skill/courtesy and street/highway design. There are a lot of places where a right lane begins for no apparent reason, and then ends abruptly, usually on the far side of a signaled intersection. A certain percentage of rather discourteous people will attempt to drive in this lane as far as they physically can, and then swerve into traffic at the last second, causing everyone else to hit their brakes.
Most cases of this could be eliminated by only terminating right lanes into right turn only lanes, preferably with a cement barrier to prevent people from illegally going straight through the intersection.
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Re:How much of this is really necessary? (Score:1)
Bufferers (Score:2)
I occassionally drive north on US101 to San Francisco during afternoon rush hour. Traffic is usually very heavy between the San Mateo bridge and I380 a few miles north. At that point, enough people get off the 101 that traffic opens up until you to San Francisco.
The traffic bufferers are fine in the heavy traffic. Less stop and go, and as has been noted, they 'plug' up the lanes so people stay put.
However, when traffic opens up and people should be driving the speed limit, the "bufferer" guy is always the one who sits in the left lane and forgets to get up to 65. By the time his buffering algorythm has informed his brain that he can speed up, several people have already made dangerous lane changes to get around him.
So, while a theoretical approach might make sense, without practical observations on traffic condition in particular locations, it just makes you look like a bad driver and gets others frustrated enough to do stupid things which could endanger you.
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Re:Commuting. (Score:1)
Cars cost more then Gas. They cost insurance and maintanence. Which does add up to a LOT more then $50 a month in the long run, especially if you do something dumb like lease a car.
Sadly, the dollar value isn't enough to get ppl off the roads and on the busses. Because there's more to life then just commuting.
Books on this subject? (Score:1)
I've culled all the URLs I can from the posts above, but I'm looking for some good texts, too.
Please, suggest a few!
God I LOVE passing on the right! (Score:1)
Yeah! Fsck you you slowpoke! SLOWER TRAFFIC KEEP RIGHT! The PASSING lane is for PASSING you moron!
Then there's tolls.
It tends to be in states (like Florida) where there's no state income tax - DAMN, $1.50, for one lousy toll? (of course this road is like a ghost town, because nobody can afford to drive on it - it's the hwy just east of Orlando).
Then there are states like California, where there is an obnoxious state income tax, and NO toll roads (yea! I'm for that - on some of these roads the booth slows you down so much that you don't really save any time over the sidestreets).
Then there are states like Illinois, which just SUCK, because the state income tax is high, and they still bend you over at toll booths.
"The number of suckers born each minute doubles every 18 months."
-jafac's law
Re:I can't beleive this hasn't been done before. (Score:1)
This sort of micro modelling was starting to come about over five years ago in Scotland.
dave
they've got it backward (Score:1)
Re:This sounds really cool (Score:1)
Part of the problem is that if you reduce the congestion, by building a new road or whatever, you make it less painful to drive--therefore more people will, bringing you back to the same problem.
Re:we could use that out here / different variable (Score:1)
Everybody's LOST, because every frickin street is named Peachtree.
"The number of suckers born each minute doubles every 18 months."
-jafac's law
Re:FASTLANE = blow through tolls at 15MPH? (Score:1)
Re:Traffic Simulation Software (Score:1)
Here are the names of some: TranPlan, TransCAD, EMME/2, TModel/2, TranNetSim, and QRS/2.
Their prices range from (US) $70 - $25,000 per computer license."
Obviously, these aren't doing any good.
"The number of suckers born each minute doubles every 18 months."
-jafac's law
Re:Urban sprawl hurts too (Score:1)
Re:Oddity: Traffic lights *CAN* speed up traffic? (Score:1)
"The number of suckers born each minute doubles every 18 months."
-jafac's law
Re:Traffic musings (Score:1)
I remember it being more relaxing to drive this way, but this works in the "fluid" state, not in the "jello" state, 'cause that's when people jumping in front of you causes a problem.
Re:Traffic musings (Score:1)
As to your second point, check out the web sites that other people have posted. One of them has the observation that even though some people will cut into your buffer, they cars that don't cut in front of you form a "plug" of patient drivers who don't change lanes, and that "plug" holds the lane-changers behind you.
- John
Big Huge SimCity (Score:1)
Re:Traffic musings (Score:1)
Re:Traffic musings (Score:1)
- People waiting too long to move when traffic in front moves (with slow-moving trucks failing to keep right greatly exacerbating the problem);
- People not merging before lanes close, forcing traffic to stop to let them in;
- Opaque vehicles, such as semis, panel trucks and SUV's, not allowing any visibility past them and increasing the necessary following distance (this reduces the carrying capacity of the road). And every time one of them moves between two cars, the usable pavement decreases again.
I have never understood the people who drive that way. I watch the traffic several vehicles ahead, and I can often manage just fine by "driving" the cruise control while the driver right in front of me has to hit the brakes. It's not hard to guess how I have 82,000 miles on the original brake pads. It only takes one. A single driver who reacts to a near-miss by stopping to recover from the scare will do it.We could get rid of a lot of these problems by having tighter qualifications for drivers, and eliminating things like cell-phone use while in motion (vehicle-integrated cellphones could easily be made to refuse to dial or answer if the driver was alone and the car was moving). The problem is, we lack the will.
Oddity: Traffic lights *CAN* speed up traffic? (Score:1)
A traffic light can speed up traffic throughput (!).
Reasoning:
Drivers don't monitor the distance between themselves and the car infront. They monitor speed. Front car slows down, they slow down, etc. This leads to: if one car brakes, the next will brake, etc. etc., leading to braking "waves". This most often happens near narrowing entrances (eg bridges, tunnels).
An arbitary stoplight placed a distance back from this narrowing can be used to stop the multiple brake waves into one larger brake-and-go (more fuel efficient, too, I guess) that gets stopped at other already present traffic lights before.
Oddly enough, throughput increased from 8000 cars/hr to 12,000 cars/hr.
This was a few years back when i heard it, so I can be completely off, too
Urban sprawl hurts too (Score:1)
It's easy to say, "people would ride public transit if it worked". But the simple fact is that "modern" urban developments, like what is now San Jose, are incredibly hostile towards working transit systems. Consider:
- Residents don't want busses going down residential streets, but major streets are far enough apart that it can be at least a 15-20 minute walk to the nearest bus stop.
- San Jose can be reasonably neatly divided into two pieces along route 280. South of the freeway, the city is primarily residential, but all of the jobs are north of it. This means that, in a north-south transit system, everybody will get on at the south end and get off at the north end, meaning you need higher capacity than if people were continuously getting on and getting off.
- People are already quite attached to their cars, and I'd suspect the automotive and petroleum industries have quite a bit more political clout than the nonexistent mass transit industry. So funding is more likely to go to big road projects than to big transit projects.
- And without funding, public transit is stuck at the same level it is now: busses that run on extremely sparse routes every half hour at most, and sometimes just don't show up.
All of this means that public transit systems have to fight a hard uphill battle to keep the minimal level of service they have now. And this level of service isn't encouraging; when it takes six times as long to take the bus as it is to drive, anybody with a car will prefer to use it at almost any cost.Old hat, I'm afraid (Score:1)
Re:This sounds really cool (Score:1)
Re:FASTLANE = blow through tolls at 15MPH? (Score:1)
I don't know what size the american transponders are, the kind we use in Norway is about the size of two long fingers and is usually hidden behind the rearview mirror. The system has been tested up to at least 250 km/h (156 miles/h) which is way above the speed limits.
It is meant to work at any speed, but athorities tend to set a 60 km/h (37 miles/h) limit anyway because there are always some who have to stop and pay with coins and they don't want a mix of high and low speed traffic.
Re:Oddity: Traffic lights *CAN* speed up traffic? (Score:1)
This makes a road largely self-regulating. You can put in more and more cars, traffic slows down but throughput increase enough to accomodate them. Unfortunately this breaks down as distance between cars approach zero. Cars aren't zero-length.
Re:Some thoughts on stoplight timing (Score:1)
Everybody on motorcycles! They use less space.
Re:My other theory of drivers (Score:1)
You answered your own question, Alan.
Applying it to real life (Score:1)
Unfortunately, the way it is enforced is rather scary. They have electronic cameras placed at intervals along the road. The cameras do OCR on each car's numberplate as it passes, and if your average speed exceeds the limit, you get a fine+points through the post a few days later. Being digital, the cameras never run out of film, and as they track your average speed, the normal trick of slowing down when you see a camera and speeding up inbetween does not work.
Apparantly the caught 4300 speeders on the first day the system went live. And of course, tracking cars all over London via their numberplate isn't an infringment of civil liberties. Honest.
Re:Books on this subject? (Score:1)
Search Amazon or Barnsandnoble with the keywords "Transportation Planning" or "Intelligent Transportation Systems" for texts.
Finally, because this is a simulation, the lessons taught by: Simulation Modeling and Analysis by Law & Kelton (ISBN 0070366985) must be observed. TranSIMs perhaps needs a refresher in the basic statistics that control all simulations.
Re:Some thoughts on stoplight timing (Score:1)
btw, some terminology - the diamonds you refer to are called 'loops'. They are literally loops of wire in the road surface that senses when a large piece of metal passes over them. When a traffic controller is using detectors (loops or otherwise) it is said to be actuated.
aj
Re:we could use that out here / different variable (Score:1)
Seriously, I wonder if these folks have taken into account the possibilities of sporadically placed street signs.
Shock Wave (Score:2)
I have the solution based on this analogy! (Score:1)
This sounds really cool (Score:1)
That they can put this kind of effort in is really interesting, and the practical applications like variably-timed onramp traffic signals and wireless traffic co-ordinaters sound useful, is it really worth all the effort? Why not just telecommute or encourage people to use mass-transit?
Who am I?
Why am here?
Where is the chocolate?
How much of this is really necessary? (Score:1)
around where you live, it's pretty clear that
most of them arn't particularly designed well.
An ideal road system would minimize the number
of stops neeeded to go somewhere, as this would
both reduce waste of fuel (F=MA), wear on
the brakes, and reduce time spent behind
stoplights (or otherwise waiting for other cars
to act). IMO, tossing a supercomputer at the
problem is a bit silly when the problems are
obvious.
Maxis might actually be of some help here (Score:2)
Jeff
not quite... (Score:1)
Heating isn't exactly what makes a solid into a liquid. More precisely, it is the _exciting_ of the molecules. So instead of heating the cars in a jam, we just need to get them excited! I don't know about cars, but what works for me is a little fender bumping, some hood rubbing, flashing headlights, etc.
Scientific American Frontiers (Score:1)
Re: The Vacation Factor (Score:1)
Tucson is the opposide, Winter time is the worst (all the vacationers come home.)
*Carlos: Exit Stage Right*
"Geeks, Where would you be without them?"
Re:This sounds really cool (Score:1)
Of course it is worth all of the effort. How often do you sit at a light, not waiting for the opposite traffic that has long since passed, but instead just waiting for the light. A smart system would be able to adjust accordingly and let you go on your merry way more quickly. In the mean time, you are saving time, your car is saving gas, and the environment gets a little break.
The only thing that will ever "encourage" people, at least in the states, to be more efficient when driving is $10/gallon gas. I'm not even sure that will do it. A new car already costs half a years income for most people and it doesn't stop them. Going on your own schedule is just too convenient for Americans to be troubled with cost and environmental issues.
Re:I have the solution based on this analogy! (Score:1)
The Important Questions (Score:1)
Is it possible for Quantum Tunnelling in this model? Or is this strictly a classical model with no Quantum bias?
Is there a method for sublimation? (Transition from Solid to Gas (ie. Carbon Dioxide.))
If traffic gets too "pressurized" (like in the center of a star) will the result of Gridlock be a black hole?
*Carlos: Exit Stage Right*
"Geeks, Where would you be without them?"
Re:How much of this is really necessary? (Score:1)
Much like saying that spending time researching and developing new drugs is a bit silly when it's obvious that cancer kills becuase of rapidly dividing cells!
The model of traffic could really help figure out HOW to make this ideal traffic system. Which would make me VERY happy... my commutes recently have all been part of the "Park on the Highway Festival" that thousands of people have involuntarily joined.
Telecommute? I wish. Maybe soon.
Interesting! (Score:1)
I hope they take weather into their equasions: I know a lot of people who look out the window before they decide to take public transit or jump in their car (or skate to work, or whatever).
Re:This sounds really cool (Score:2)
Oo!oo!I know this one! There has to be a $6/gallon tax (putting gas at about $6.75, I suppose) for drivers to take into account all the consequences of driving: pollution, increased death rates, The Gulf War, etc. This according to some study I read for work in July. Can't remember the source, though.
Re:This sounds really cool (Score:2)
Oo!oo!I know this one! There has to be a $6/gallon tax (putting gas at about $6.75, I suppose) for drivers to take into account all the consequences of driving: pollution, increased death rates, The Gulf War, etc. This according to some study I read for work in July. Can't remember the source, though.
Re:How much of this is really necessary? (Score:1)
Yeah todays roads tend to be poorly designed for todays traffic. But a lot of that is caused by a carry-over effect. The road started as wide as a horse and buggy. People built houses. Now the road can't get any wider, without the destruction of people's property, which everyone will yell and scream about.
The problem may be obvious but the solution is definetely not. So the scientists are modeling the problems (including unlikely things like people riding their brakes a 1/2 second too long), so they can find solutions.
-cpd
maybe... (Score:1)
Some thoughts on stoplight timing (Score:1)
I think one of the areas where city planners can improve things out there is with stoplight design.
For example, the "diamond" stoplights (stoplights that detect cars at the light, and change accordingly) are an excellent design when traffic is extremely light, such as the middle of the night. It is a terrible design when traffic is moderate to heavy.
What happens when traffic is moderate with diamond stoplights is this: they slow down traffic. Since the lights are controlled by traffic, which is essentially random, the chance of a given stoplight being green is simply a flip of the coin. This makes "liquid" traffic "solid" traffic.
The ideal design once traffic hits the "liquid" state is to have the stoplights be timed lights. In other words, If one is going down the road at 40mph, all of the lights are timed to be green at the time one drives throught them.
Once traffic gets really heavy and enters a "solid" state, all bets are off. The only options traffic lights have are to either be timed at a slower driving pace (10mph or whatever the traffic can handle). One also needs to keep the main artery intersections green for as long as possible.
- Sam
Interesting results. (Score:1)
The team in Germany has determined that the best way to keep a traffic flow fluid is to stagger the traffic merging onto the highway in a random manner. They initially tried a regular pacing of cars onto the freeway, but this turned out to be worse that just letting people come on whenever they got there.
Their work seems to be focused on maintaining what they call "synchronized flow" in the article, or the intermitent state of driving at a fair speed in dense traffic, and usually signals the onset of a jam somewhere around the next on ramp.
If anyone is interested further, send me some mail and I'll give you some other related articles, if I can find them.
Re:Urban sprawl hurts too (Score:1)
I enjoyed riding the train to work when it didn't require a transfer to a bus, and parking cost $140 a month. The business I work for recently moved to a less transit friendly location, where parking is free. This move added about 30 minutes (one way) to the commute time by transit, due to the time waiting for a bus and the time required for a bus to travel.
Portland is nice in that major streets are fairly close together, so it's usually a short hop to a bus location. In addition, we have many park and ride locations along the light rail line.
Don't get me wrong. I'll use transit. But there's only so much inconvience I can take.
As far as funding, the feds seem to be fairly free with their transit funds. Both Portland and Eugene, Oregon have recently received several million dollars in transit funds to expand their local bus systems.
Russ
Re:This sounds really cool (Score:1)
As for encouraging people to use mass-transit, although it is a good idea, most of the techniques used today aren't working. The most effective technique is to almost abandon the idea of getting the baby-boomers off of the road, they have been so used to having their own car and using it for everything that they won't give it up. Instead, market the Gen-X'ers and younger to ride it before they become too used to the regular pattern of driving. This doesn't happen because it requires a lot of resources to get it started and keep it going while there aren't very many riders.
I have talked to people who have set up bus systems in towns and have agreed that this is the way to go.
Re:not quite... (Score:1)
1. Unleaded 93 octane fuel
2. Mobil One synthetic 10w30 and a good oil filter
3. Goodyear racing Eagles
4. A hand applied wax job.
5. A cute redhead as my owner and primary driver.
Re:Some thoughts on stoplight timing (Score:1)
It seems that after 9 or 10pm the lights stop working with each other and go on their own schedule to advoid the really long delays that the timing system can introduce. I like that feature.
As far as "waves" of traffic go - It's kind of fun to watch a bunch of cars stopped at the light finally get to go through - then a dead space for about 2 minutes - and then halfway through the next wave the light goes red. hehe.
Re: The Vacation Factor (Score:1)
Most interesting of all, is that I live in Florida. I know we get lots of tourists here for the beach, but it's summer! I didn't know anyone came to Florida in the summer. However, for some strange reason, it's actually cooler down here (90-95 F) than up north (95-100 F).
Re:One more thing: merging onto freeways (Score:1)
Personally I like to be going about 10MPH Faster to give myself some leeway. I can't stand the morons in their minivans (note that not all minivan drivers are morons; just that the minivan is the vehicle of choice for the average moron) who poke along down the acceleration ramp and merge into 75MPH traffic at 50MPH. And then they wonder why I wave to them as I'm passing.
thanks (Score:1)
Re:Traffic musings (Score:1)
Don in Seattle.
Vaprorize them ... envelope calculations : (Score:1)
Let us consider this :
a mirror roughly 6000 meters squared ( cross section to the sun and not hte actual surface area of the mirror without accounting for angle of incidence , of course ) would bring enough energy in one second to vaporize approximately 28 tons of iron . ballpark estimate ; 1 ton per vehicle ( for simplicities sake we will assume that the majority of the mass is an iron derivative and discount aluminum engines --- not to mention fieros ) that would remove a traffic jam in Chicago's loop every hour .
I will be fine as I have several layers of mylar lying around here somewhere and can get up to a 95% reflectance . It should , at the worst cook the Mylar and let me scramble out of the new oven that I was driving
your Squire
suqireson
My other theory of drivers (Score:1)
signed,
drivers
Personal Rapid Transit (Score:2)
Some optimizations are not very obvious (Score:2)
Or the traffic sensors are overly sensitive.
Or the traffic designers put in some light changes to keep that light synchronized with the rest of the traffic flow.
Or you simply did not see the car which hit the sensor, turned right on red, and vanished from sight before you came along and got the red light.
Re:Interesting results. (Score:1)
LinCity might actually be of some help here (Score:2)
Re:This is more useful without drivers (Score:2)
The advantage of computer-controlled cars is they could chat and agree to do things such as alter spacing and balance between lanes, and cars would not jump ahead in the line to the detriment of everyone behind them.
Re:This sounds really cool (Score:1)
but if you ask me, they forgot to include global warming, which would probably put the cost of gasoline at a MUCH MUCH higher price, once all life on Earth is eradicated.
"The number of suckers born each minute doubles every 18 months."
-jafac's law
Re:How much of this is really necessary? (Score:1)
Make the driving test so difficult, that only competent drivers can pass it. Remove the idiots from the road, and voila! less cars=less traffic congestion.
Methinks that the Oil Company lobby has something to do with why it's so easy to pass driving tests. More drivers=more consumption.
And as far as the I-94 goes, I used to live in Chicago, and man, it's bad there, but I tell ya, there are MUCH worse places in the country to drive, and most of them are in the northeast. Boston in particular is very unforgiving, crazy narrow streets winding around aimlessly, going from one-way to two-way, back to one-way for no reason. But Illinois' number one problem will always be the Illinois Department of Transportation, who's slogan should be:
IDOT: We can't even spell "Idiot" right!
"The number of suckers born each minute doubles every 18 months."
-jafac's law
Re:Traffic musings (Score:1)
Unfortunately, the guy in front of you apparently has hemmorhoids.
"The number of suckers born each minute doubles every 18 months."
-jafac's law
Re:One more thing: merging onto freeways (Score:1)
ALWAYS accellerate into a lane change. If you do not, you will effectively be moving BACKWARDS, relative to the traffic around you. Ask yourself: is that safe? If you're constantly moving FASTER than the traffic around you, relative to them, you're moving forwards - not backwards, backwards is bad. Backwards is unsafe. Unless you have eyes in the back of your head, or can take your eyes off the road long enough to turn your head around, or use your mirrors.
Also, signalling for a lange change would be nice, but, that's probably too much to ask for for most people.
"The number of suckers born each minute doubles every 18 months."
-jafac's law
Java Traffic Light Simulator (Score:2)
Traffic musings (Score:1)
A hypothetical driver comes up on stopped traffic on a freeway, and is forced to stop. A few seconds or so later, traffic restarts.
"Ah", he says, "Moving again.", and start to drive at the speed of the car in front of him, leaving a car length or two maybe. A few seconds later, the car in front of him puts on his brakes, lighting his brake lights.
Now they teach you in driver's ed that you're supposed to leave one car length for every 10 miles per hour, and you're supposed to start braking the instant you see the car in front of you put on his brakelights, both to reduce speed, and to warn the car behind you to start braking also, but hardly anyone seems to do that. Instead, the typical action seems to be to coast as long as possible, then brake to avoid collision.
The result is that our hypothetical driver has to break harder and faster then the car in front of him because of his delay.
If a dozen or so people do this in a row, it will naturally cause the traffic to stop and go in a ripple pattern.
Just watch the brakelight patterns next time you're in heavy traffic on a curve. The lights move backward in waves; the speed of the wave is a combination of the drivers' individual reaction times, and the drivers' wishful thinking time.
If you can figure out the average speed, and move at that exact speed, and force yourself to leave an appropriate interval between yourself and the car in front of you, you can break the stop & go pattern for yourself and the cars behind you. In other words, when the car in front of you zooms ahead, go at a constant speed, and let a gap open up in front of you. Then, continue at that constant speed, so that you catch up to the car in front of you in the same amount of time he has braked, stopped, and started again.
The result is that you move at maybe 15 mph, as opposed to 0, 25, 0, 25
Of course, you lose a little because people cut into your buffer space, but the sort of people who will change lanes to take your buffer space will change right back when the other lane moves again, so it appears to average out over time.
I have no idea whether this helps anyone but myself, or whether I'm just being annoying as hell, as my wife claims
I'd love to see a sim-traffic game.
Interesting.. (Score:1)
putting makeup on while driving == erractic
talking on cell-phone while driving == faster/slower than normal
screaming at the kid(s) in the waaaay back of the friggin min-van to "shut the hell up!" or "Do not touch him/her/them AGAIN!"
eating sloppy junk food while driving == crashes
smoking and dropping cigarette in lap == 20 car pile-up
etc.......
BTW, LANL must be the coolest place to work.
Re:Traffic musings (Score:1)
-freeknw
It's a solution... (Score:1)
Some years back I noticed that different regions have distinct driving styles, and that someone (like me) from a different region with a different style could be in, or cause, trouble - like a foreign particle acting as a seed crystal or a cavitation site.
Then there are places - like California - where waves of immigration from different regions have produced a wild mix of different driving styles.
And lots of unforseen consequences of government intervention. For instance: The 55 MPH speed limit changed freeway behavior nationally - from mutual repulsion (for safety) to clumping (forming a herd to make it harder for the blue-coated peredator to pick out a victim).
Re:Traffic musings (Score:1)
I remember my mom teaching me to "buffer" ~15 yrs ago. She was from Los Angeles and San Diego and was used to looong freeway commutes. Apparently, this was what folks learned to do, hence the infamous "bumper-to-bumper at 65 MPH" style often associated w/ L.A.
I now live in Seattle and do the same thing. It keeps me occupied, reduces wear-and-tear on my brakes, clutch and engine, and folks behind me sometimes pick up on the idea.
Stop-and-go SUCKS on a motorcycle. More power to anyone trying to reduce it.
Re:How much of this is really necessary? (Score:1)
You will have to try the make the best of the given situation (best being a compromise between the costs of the buidling works (not only in the financial sense, you will also have to take into consideration environmental aspects, people living there, ...) and the achieved benefits.)
I think (although, of course, I am not an expert on traffic), the cheapest thing to change is the schedule of the traffic lights. By using computer simulations you can probably find out how long to show green and red lights on any traffic light to maximize throughput. This problem is similar to task-scheduling problems in computer operating systems. Using super computers to simulate the traffic is probably a better idea than trying the whole thing out in the real world :) And you will need quite a lot of processing power to simulate a real world traffic situation.
It may cost a nice sum of money to let those super computers try to solve the problem, but just imagine how much money could be saved if an average of, say, 10.000 people in their cars save only 10 minutes every day going to work and back home, possibly just by changing some traffic lights. Time, fuel, pollution, ..., (what a wonderful world it could be:)
Christoph
Re:not quite... (Score:2)
6. Lower center of gravity or lift kit (pick one.)
7. Electronic defensive and offensive counter measures (radar guns are more useful than detectors!)
8. Full bottle of N2O (gas masks not included.)
9. Air horns.
10.Dual 3" exhaust.
I figured this out about 6 years ago.... (Score:1)
Of course then we moved onto traffic jams and how the same behavior applied....and the list of variables we deduced was quite impressive. I wish I could remember more, but I was, um, slightly in a non-remembering physical state if you take my meaning.
then we got inside, he got punched in the throat whilst in the pit, and I had to help break up a chick fight.
*sniff* memories.....
Re:Some thoughts on stoplight timing (Score:1)
You know, I get the sense El Camino Real, a major road through silicon valley, is not coordinated. I notice that most of the lights have diamonds, and that the red lights are always holding up traffic.
Is it common to have a given stoplight be both diamond-activated at low-traffic hours and coordinated during medium-traffic hours?
Here, in the bay area, the only series of coordinated lights I know of are in the city (San Francisco).
- Sam
particle man particle man (Score:1)
I commute from Boston to Framingham each day. I used to be averse to passing on the right, but it makes me feel so good. I like to drive between 75 and 80 mph and stay in the left lane. I can't stand people who drive the speed limit in the left lane. If someone is coming up behind me who is moving faster than me, I pull into the middle lane and let them by. I wish that more people did this.
The only purpose that tolls serve is to give people something to do. Most toll plazas are poorly laid out. With FASTLANE [mtafastlane.com] open for the length of the masspike [masspike.com] (why does their site need Java?), things have not gotten better. FASTLANE has removed one lane (typically) from each toll station that was previously used by people paying with Real Money (TM). At Exit 13, the FASTLANE replaced one of the two 'double server/single queue' lanes (two toll booths in the same lane). Either pike officials realized that the ds/sq system was inefficient, or they aren't really concerned with efficiency. I would like to get a FASTLANE transponder, but I refuse to. I'm waiting until the fall, when, supposedly, the system will be compatible with the EZPass [ezpass.com] system. EZPass is better (IMHO) for two main reasons:
- To get a FASTLANE transponder costs $27.50, including a refundable deposit. An EZPass transponder requires a $10 deposit, unless you start your account with a credit card, in which case the deposit is waived.
- EZPass is bank agnostic. A FASTLANE account requires a $50 deposit. Unless you are a BankBoston customer and you pay tolls through your checking account. EZPass requires a minimum deposit of $25 for everyone. Both systems require a minimum balance (FASTLANE requires $20). Why do both systems need to have some of my money all the time?
Is anyone else bothered by the fact that FASTLANE needs a corporate sponsor? I have to pay a toll, and the Commonwealth is either taking money from BankBoston, or BankBoston is getting free ads in exchange for some service they are providing the Commonwealth (administration of accounts?) About a year ago, I noticed a FleetBank ad on the reverse side of a toll schedule. I do not need spam in my car.
And what about the areas not frequented by commuters? There are typically fewer toll booths, one of which is now replaced with a FASTLANE. What incentive is there for the people in those areas who don't use the highway that often to get a transponder. Is the goal here to get a "transponder in every car"? For what purpose? Will we start getting speeding tickets in the mail based on the data collected from the transponders (distance between tolls divided by elapsed time equals average speed)?
I could take the commuter rail to get to work but I don't. I would either have to get up earlier than I want to, or I would not be to work at an acceptable time. I also have meetings outside of work that I have to go to and the commuter rail schedule does not give me the flexibility (or reliability) that I need for my schedule. Just today, my roommate was 20 minutes late coming home becuase a lightning strike disabled switching on a four mile section of track, stopping traffic in both directions.
I wouldn't mind being a particle. Travelling at relativistic speeds my commute would take one millionth of a second. I could get eight hours of sleep a night and still go to bed at 1am!
we could use that out here / different variables (Score:1)
(A) When traffic is stopped, people like to wait for the car ahead of them to move up a few lengths before they go. I think this is a function of braking distance and experience with driving the particular car.
(B) If I wait for a shorter time period, leaving a smaller gap, the person behind me waits longer, so the total gap reduction (and speed increase) is reduced, if not negated. This indicates the driver behind me is also watching the car in front of me. From the point of view(frame of reference?) of the driver behind me, he's "pacing the traffic". From the PoV of the driver behind _him_, he's stalling.
Kinda wierd, makes me wish I could get a big electromagnet to tow the slacker along.
(C) For every car '1' moving at speed x, a "terminal point" is created. This "point" is the spot where a car '2', behind '1' and moving toward '1' at speed (y), will touch '1' after time t. t is the measure of time needed for '2' to reach '1's position at '2's current speed. The point slides forward, backwards, and sideways, depending on the relative position, speed, and acceleration of '1' and '2'. I.E., if '2' changes lanes, terminal point '1-2' no longer exists, but a terminal point '2-3' may be created, and terminal points '1-4', '1-5', and so on, may still be in effect. If I look at cars in terms of energy, then I could probably apply this item to a global scale.
I figure that if the above items are near-correct, certain "driving in traffic" subjects can be added or modified to fit a drivers-ed curriculum.
Which won't matter in Georgia, because the drivers-ed program was ditched, and stays ditched, for "cost-reasons".
Traffic Flow (Score:1)
Just treat every object on the road as a 'friction' point. The closer one object get to an object, the more it slows down. If there is an object with a few feet of traffic at the edge of the road (Any object large enough to be seen at several car lenghts), traffic will slow. The PERCEPTION of the size of the object and it's proximenty to the road seems to dictate the loss in speed.
So, when you see cars ahead of you stomping on thier brakes for no apperent reason, you can bet the PERCEPTION of the size of the objects ahead of that car has been viewd as being large!
This has been obvious to me for at least 10 years... If you are able to reduce the 'friction' around you, your level of stress goes way down.
This is more useful without drivers (Score:1)
If cars were under central control, a computer could merge them and speed them up simultaneously on encountering a narrow place. I don't think there is any way to teach individuals to safely speed up and merge.
Jim
At least some optimizations are very obvious (Score:1)
(Columbus, Ohio) where there are crosswalks,
buttons for the crosswalks, and 4-way
intersections. At these intersections, the
light will periodically change even when there
are no cars waiting to use the intersection the
other way and no pedestrians have pushed the
button to request walk across traffic. This is
quite irritating...
Re:Traffic musings (Score:1)
All that time sitting stopped behing the wheel has given me ample opportunity to study the flow of traffic. The ripple effect is exactly what happens. I have used the same technique of proceeding at a fixed speed and it has the interesting side effect of smoothing out traffic that is following me.
I'm convinced that one stupid move on the part of one driver can have very large consequences to the whole traffic flow. This is the idea speculated in the article as chaos theory.
But this goes the other way too. A smart move on the part of one driver may impact many other cars positively.
Ultimately, I think it comes down to driver impatience, and not being aware of what other cars are doing.
I don't see how sophisticated traffic models are going to help these two problems at all.
I knew it! (Score:2)
CNN today reported that a massive increase in tire production by the Russians has strained diplomatic relations. The situation has been made worse by the prospect that China may be retooling to produce even smaller and more efficient cars. The Whitehouse had no official comment today, but rumor has it that a new SUV will be released to combat the communist threat. "Citizens need to be aware that driving is no laughing matter! The future of democracy may well be at stake!" However, a random American was quoted as saying "I don't care, as long as I get my super-sized cup holders on time!"
--
Re:Interesting.. (Score:1)
Well, I've been working at one of the other national labs this summer, and I can't wait to leave. The labs have very cool toys are some neat projects, but their Big Brother policy on computer use just kills me. If they had any idea how much time I spend on Slashdot, I think I'd just be taken outside and shot.
Matt
Re:Traffic musings (Score:1)
Not entirely, because if you are moving at the average speed, there will be some points where the average is below the current speed, and points where it is above. When the latter occurs, you'll have to brake.
The other problem is the only way to get a reliable average speed is to wait for the traffic jam to be over and average out the speeds at certain intervals. (This sounds like an integral problem. Ugh.) So you can't do this well while you're in the middle of the traffic jam's time frame.
Of course, you lose a little because people cut into your buffer space, but... it appears to average out over time.
Except when that person cuts into your space, it again upsets your average speed. You'll have to decelerate from that speed for each cutter, and then accelerate when each leaves (assuming its the one right in front of you).
You cant solve the problem.. best you can do is smooth it a little. (I only say all this because this is exactly what I try to do in traffic.)
What I advocate more, if you can swing it, is to get three of your friends to drive next to you in different lanes, and then stand still until the end of the traffic cluster is about a tenth of a mile away, and then go. This is the Java-esque producer-consumer model solution, of course.
Regards,
Re:The Important Questions (Score:1)
Commuting. (Score:1)
I have a choice. 30-40 minutes to drive to work, or a 90+ minute commute via train/bus or train/taxi.
So, to get to work at 9am, I have to leave at 8:30 or 7:30. This means I have to get up at 7:30 or 6:30.
If I get off work at 5pm, I will get home at 5:30 or 6:30.
So here are the choices:
Option 1 (Car):
Leave at 8:30
Get Home at 5:30.
Total commute time 60 minutes.
This gives me more time with my family, and more time on my own projects.
Parking where I work is currently free.
Cost of gas is still up in the air, as I haven't tracked it.
Option 2 (Train/Bus)
Leave at 7:30
Get Home at 6:30
Total commute time 180 minutes (3 hours).
This gives me less time with my family and or other projects.
A plus here is I have more time to read, assuming I can get a book out of my backpack while packed into a standing room only train.
A transit pass is $49.00/month. I believe this is less expensive than the cost of gas for one month of commuting by car.
I'll take the additional time not spent commuting.
Re:Some thoughts on stoplight timing (Score:1)
The problem is that as traffic volume increses - during rush hour, say - there are more cars trying to get through the system than will fit. Cars can't drive at the design speed and this means that they will 'stack up' causing even fewer cars to make it through the system. Bam! a phase change has occurred. Making the system more adaptive is a goal that we and every single one of our competitors are trying to achieve.
Hopefully my employers will never find out about this, but I think the only real solution is to put fewer cars on the roads. Mass transit will help do that, but here in the US you're considered some sort of second class citizen if you ride the bus to work (except in a few urban areas - eg, NYC). Also, people just don't want to give up the freedom that comes with having their own vehicle parked out in the lot. I like the idea of telecommuting - I could do 90% of my job from my house and I know many of you reading this could too. But to a great extent corporate America still operates under the paradigm that if you aren't at work, you aren't working.
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