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Programming IT Technology

Intelligent Traffic Management? 19

Posted by Cliff from the my-stoplight-has-a-low-IQ dept.
jcwren asks: "I was driving to work one morning, cursing the so-called 'traffic engineers' who configured our glorious network of traffic lights, when a few questions occurred to me. Do cities actually have a traffic management system that's either learning or adaptive (fuzzy logic, pseudo-AI, whatever)? I seem to remember that years ago that Phoenix had a far better traffic control system than Atlanta has ever had. What are peoples' thoughts (logically, not emotionally) on how traffic is managed in their cities?"
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Intelligent Traffic Management? More

Intelligent Traffic Management?

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  • Hi.

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  • In Irvine, CA(Orange county) we have sensors at the pedestrian wlakways. You can see the cement clearly cut out ina rectangle. When a car goes over it, it signals for the light to turn green. Otherwose all the major streets are green and the smaller ones are red. THe smaller streets that intersect smaller streets are ona time-sharing mechanicism. IT also matter on the time of day, during night(10+ PM) it takes longer for the lights to change.
  • Downtown Portland uses a somewhat adaptive timed signal system. When there are no events in the grid (ie, normal traffic flow, no transit trains or bridge lifts), the signals change at a rate that you can hit every green if you make the first one, maintaining a speed of 17-20 MPH.

    If a light rail train enters the grid, the grid retimes itself by a couple of seconds as the train asks for its signal to be changed on demand (the operators have buttons to request signal changes and gates to go down by stations on the line).

    If a bridge lift occurs, traffic parallelling the Williamette River gets longer green lights, allowing traffic to cross the traffic waiting for the bridge to go down.

  • My ride to work is nearly a straight shot on a four lane (not including two-way left-hand turn lane). There are many lights (probably 10-15 lights, during the 20 minute drive). Due (apparently) to some zoning oddity the speed limit is artificially low: 40 MPH most of the way, 35 in some spots. The road could easily handle 50-60.

    A few years ago, a lot of money was spent "synchronizing" the traffic lights due to complaints from drivers. Some say it didn't work, but I have found that during times of high use (i.e. during my commutes) they ARE synchronized--if you drive 50-55. That's right, if you drive 10-15 MPH OVER the speed limit you can sail through every light while it's green (assuming no one is in your way).

    So my conclusion: Sane traffic management is not what is being optimized. My question is: Why would it be? Sure, driver's want quick rides. But shop owners would like people to drive slowly (if not stop) to read their signs. City Hall likes people to speed because it brings in revenue. Etc. There are many different factors to optimize for, don't be surprise that YOUR goal isn't met as well as you'd like.
    --

  • I can only speak from experience of the UK, where CCTV is everywhere. This might not be the case near you, so this probably won't apply.

    Now, every major road junction in most major towns/cities in the UK has CCTV cameras watching the traffic flow (you can even watch them in London on the BBC website [bbc.co.uk]). These images are being watched (almost) 24/7 for traffic buildup, and the people watching them have to power to change tarffic light sequences on any of the big junctions (and other measures such as lowering speed limits further up the road to reduce traffic buildup etc)

    Obviously the lights are sequenced to do the best they can automatically (and change their timings throughout the day to suit traffic flow in/out of the cities), but by putting a human in the loop you can solve problems that computer programmers never envisioned (eg, car accident right next to the junction). Every so often they manually tweak the standard settings to take account of overrides done in the last month

    I find it hard to see how a computer system could possibly match this. How can it tell whether a queue building up is caused by bad traffic light sequences or a car breaking down in the middle of the road? How will it know when to give up trying to tweak the lights and just call in a traffic policeman to sort out the mess? How will it know when to phone Local Radio stations to get drivers to avoid the area? How will it know to clear a road so an ambulance can get through? How will it envision one off problems (eg the Superbowl being held in a city probably screws with the traffic that day).

    The trick they need to work on is creating systems that assist humans in controlling traffic flow, not trying to do the things humans do best.

  • Also called another way to make your city as unfriendly as possible to bicyclists.
  • The same thing in Paris. I know one of the computer people working on the paris traffic system [sytadin.tm.fr]. The french have thousands of sensors planted all over the place, as well as hundreds of surveillance cameras.

    There have been a number of projects to examine knowledge based "AI style" traffic management. Many small companies offer controller systems which claim to have "fuzzy logic" and are able to learn about traffic patterns. Every single one of them fails when presented with a few basic external factors such as "weekend", "snow", "construction" or "accident". But given a perfect grid system (which Paris is NOT!), and perfect drivers, and the AI systems had no problem finding a perfect solution. But the slightest change threw the whole system into chaos, and quite often killed the system. None of the marketing claims survived even a small real world test.

    So Paris has gone to its own system. The computers are doing what they do best, calculating. The humans do what they do best, adding intelligence to the chaos. Together, Paris traffic is only a mess, rather than a permanent gridlock :-)

    the AC

  • I did a search on this once. The most dangerious form of intersection is the one controlled by a traffic light. (The least has no controll at all) Second least is the round-about, which can handle as much traffic as the lights. (Except in a few extreem cases)

    The above is all according to the US goverment, and if you search their web sites enough you can find it too. (I'm too lazy today - I already lost the battle with local traffic planners who have the old Not invented here syndrom and thus ruined traffic in myk town)

    Good luck making use of the above knowlege though.

  • Here in the second city, traffic is HORRIBLE. Every other road is being repaired and the ones they just repaired are falling apart already. Taking the tollways or expressways during rush hour is like sitting on the couch, you aren't going anywhere.

    This WILL sound odd, but I've found that roads with traffic lights move faster during high travel times simply because people work better when regulated. The obvious exception is when you have multiple lights out of sync within a mile of each other. When placed properly, the road ahead is open giving people the change to actually move (what a concept in traffic!!).

    On the expressways, traffic just slows to a crawl for no apparent reason around here. Mainly because you've got people who feel a need to slow down in heavy traffic. I'd rather stop at lights with periods of going 30 or 40 than a constant 10 miles per hour on the expressways around here. For anyone that knows the area, taking 94 from Lake-Cook to 137 takes 55 minutes on average but taking Waukegan Road (Rte 43) to 137 takes 35 to 40. And you cross three majors roads (22, 60 and 176). The only reason it took 50 minutes one day is because some moron wanted to go swimming in pond with his ugly Exploiter.

    So, traffic lights are a good thing. If you're dumb enough to run a light that has been yellow for awhile you deserve anything you get. If you are creeping out on a red you deserve what you get. I want even get into trains. We need to stop trying to prevent natural selection and weed on some the population.

    I don't know much about the traffic system in Chicago (sensors, cameras, etc), but I do know what I see. To comment on the traffic circles, they're cool and traffic moves quickly through them, but I can't help but feel nervous when driving through them. And see the broken glass on the edge of the round doesn't help ;). Could they be safer simply because there are fewer of them? The same way there are less women getting into accidents because there a fewer of them driving (not sexist, that's a statistic).

  • I think you may have cause and effect mixed up here. Just because intersections with traffic lights have more accidents does not mean that traffic lights cause more accidents. More likely, the fact that more accidents happen with traffic lights is because traffic lights are installed at intersections with more traffic.

    The round-about circle intersection works pretty well if you know how to use it. But most of the people in my part of the world all want to use the outside lane.

  • Re:In Irivine, CA we have sensors (Score:1)

    by Anonymous Coward

    Not always true - in Ottawa, Canada, the rectangles are pretty obvious, and in case they aren't obvious enough, there are yellow dots on the rectangles which are more sensitive and detect the bikes. (I've always assumed these are induction plates)

    If not, how hard is it for the cyclist to push the button?

    In Montreal, Canada, where I am now, everything is timed. (not true for the suburbs). Also everything is oriented towards the pedestrian. E.g. No turns when the light first turns green, so that the pedestrians get a chance. Of course, they wouldn't have a chance without this, given the number of people that run reds when it is convenient, but cutting a single lane of traffic can reduce an autoroute's effectiveness by 50%. And that happens everywhere.
    How does it work? Hey I bike or metro, so don't ask me.

    PS> Of course, we also have problems with snow covering the yellow dots.
    PPS> If you think you've got it bad, jsut imagine how bad it would be with snow removal. Or the amount of money that goes into just maintaining the road through freeze/thaw cycles and the constant scraping of snow removal.

  • Remember, a series of lights timed for 30 mph is also conveniently timed for 60 mph! :-) ( I read that somewhere... )
  • I wonder what the people studying machine learning have to say about this subject... What if the computer learned from having its operator intervene in certain circumstances? Beyond manually tweaking the defaults every once in a while, what if every time the operator made a change the computer could recognize those factors as needing a particular action and could take it automatically the next time? The other thought that springs to mind is genetic programming... constructing large-scale complex simulations and breeding programs to find the best solution to a chaotic situation... Any experts in these fields care to chime in as to their respective applications?
  • In Apeldoorn, The Netherlands, where I live they are now installing new traffic lights and traffic managment stuff to aid cyclists get faster from point a to b. More and more intersections have intelligent systems that "know" how many cars are heading in their direction (they can communicate with other intersections). The traffic managment system can then use this information to give a better flow of the traffic.
    I don't know the details of the system, but I have indeed noticed that at a number of intersections the light for cyclists goes faster and longer to green then before... The system doesn't just waits a number of minutes, but changes the lights directly when the last car has passed.

    Grtz,
    Eon.
  • Traffic management is a brezee under *BSD! Check out BPF (Berkeley Packet Filter)!! It does policy and connection based routing!!

    ...

    Oh, wait, you mean meat-space traffic with cars. Well, then just port the BPF to automobiles and OpenSource it!!! YAY!!!!

    A wealthy eccentric who marches to the beat of a different drum. But you may call me "Noodle Noggin."

  • Actually, at 3 AM the lights where probably shifting to the morning pattern and the other direction was also all messed up.

    Several times, in other cities after major events I've seen outgoing traffic escorted by a police car -- with no siren but its give-me-a-green-light signal light flashing. Pretty effective at keeping traffic moving, although at an unusual rate matching the speed limit.

  • I actually have a bookmark to this page of Transport Research links [leeds.ac.uk]. If you're not looking for research, there's a wider assortment at Yahoo's Transportation Page [yahoo.com].

  • Err, this is direct from the goverment. Accidents per 100 cars or some such.

    Now on face value you are right, a uncontrolled intersection cannot get as many cars through as a normal one. However a round-about (Not a traffic circle) can handle almost as many cars and is safer.

  • If not, how hard is it for the cyclist to push the button?

    Psycologist have studied those buttons and concluded that they are often not connected to anything. Well at least nothing useful, sometimes they turn on the walk light, IF a car is detected wanting to cross there.

    In other words, the button doesn't make the light turn green, you need a car to come along as triggure the sensor so that you can cross!

    Just arouther reason to hate traffic lights.

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