Traffic Jams

the science.

This had me scratching my head, though. It lists the top ten most congested highways (not sure how they measure that), and I found a couple of surprises.

First, that none of them were in southern California. I would have thought that the 405 through West LA and over Sepulveda Pass into the Valley would have been a prime candidate.

Second, that they list the merge between northbound US-23 and northbound I-75, in Detroit. Only one problem. Those two highways merge in Flint, sixty miles northwest of Detroit (and my home town). And while I haven’t spent much time there lately, I have been there some, and I’m quite surprised that it beats all of the Detroit freeways for congestion. The only time I can imagine it would be a big problem is on holiday weekends with people coming from the Detroit area heading up north. Even then, it can be avoided by taking I-475 through town. I’d like to know how it got so designated. It makes me question the validity of the rest of them as well.

23 thoughts on “Traffic Jams”

  1. Having driven all of 7 of them, I’m not sure who did the figuring. I’d bet the Dan Ryan in Chicago is more congested throughout the day.

  2. As a person who drives an hour each way and has worked at Texas Transportation Institute; I’m not surprised with the findings. Their “closer look” is what I would call the butterfly affect they mention. But there are other things I’ve seen. In Southern California, I learned the devestating affect of having semi-trucks driving at a different speed than the rest of traffic. In Houston, I also learned the flaw of taking away travelling lanes too early, such as I-45 South going from 4 lanes to 3, 5 miles before you get to NASA Parkway exit. The only thing more annoying is I-45 heading North just before I-610 south where the lane drops into an exit only, so that people rush along the feeder to merge back in a 1/2 mile up the road.

    This then leads to the simple observation any quality person could tell you. Variation hurts the flow of any system. The problem of butterfly is that even a fast moving driver can cause problems that slows down the system. Sadly, the counter measures are rather pathetic in solving the problem.

    On ramp lights cause entering traffic to be slower and most are just cycled time. Bus lanes (and all trucks right) help, but they tend to only give buses their own lane and not enforce buses to only use that lane. And reversible lanes also can help, but it ignores the variation problem and simply adds more bandwidth. It’s great until you get the point of throttling in the system because the infrastructure still goes down from expanded lanes to 2 or 3 lanes.

    Best solution, enforce laws about passing on the left. Works pretty well in Germany. Another good solution is limiting who can get a driver’s license and heavily enforcing laws about driving without one. This would make both conservatives and liberals happy. The former will get better enforcement against illegal aliens. The latter will get incentive for people to ride public transportation and there I say, “high speed rail!”

  3. They forgot the most common and obvious cause of traffic jams.

    Left wing pols who purposely starve highway funds to fund their own constituencies. Complementary with this are the sheeple who think jammed freeways and 3 hour commute times are some given of natural law and won’t even consider the alternative that it’s really yet another prog screw over.

    Note to Democrats – you’re killing yourself here, all those folks sitting helplessly on the freeway are listening to right wing talk radio.

  4. Another good solution is limiting who can get a driver’s license and heavily enforcing laws about driving without one. This would make both conservatives and liberals happy.

    Except in CA where it’s a civil right for illegal aliens undocumented drivers to be on the road without insurance.

  5. Yes, I’m underwhelmed with the choices of congestion. I strongly suspect both the 405 and the 5 would qualify under reasonable criteria.

    Leland, in SoCal you left out one important injector of chaos: HOV lane entries. Watch next time you’re in a heavy-traffic situation what happens when you get near a place where you can go in or out of the HOV lane. Traffic always bogs down considerably. It isn’t even necessary for there to be much entry and exit traffic — the mere fact that someone might be merging from the left into the high-speed lane makes the left two lanes pucker up, so to speak.

    One other obvious problem: putting an entry and exit so close together that people exiting must cross the path of those entering.

    I don’t think highway engineers are at all surprised by any of this stuff. They known damn well that the only way to have smooth traffic flow on a limited-access highway is to, well, limit access. But political considerations govern such things as where exits get put, the existence of HOV lanes, random widening and narrowing of the roadway, et cetera, and wreck ideality.

  6. That was pitiful.

    “The Butterfly effect” is a euphemism for “Some asshole was forced to merge because the road either narrows or the feeder ends. AKA Widen road here.

    “Invisible Waves” is, hmm. Exactly the same issue.

    “Tragedy of Commons” is “Blame the victim.” Traffic is caused by cars! Who knew?!? Save us buspeople, you’re our only hope!

    Having spent from 4:30pm to 7:40pm last night crossing the Evergreen Floating Point Bridge (SR520 WA) (once Eastbound, stop, then once Westbound.) I’d like to add it to the pile for consideration. Two miles, completely flat, no shoulders(!), lane changes prohibited, no merges.

  7. PS: Preview is doing something odd to HREFs for me. To see the ‘live preview’, I needed to add an extra equal sign in ‘A HREF==’. Which isn’t correct HTML.

  8. I would tend to favor less access and tolling of the entire highway system. I would not be in favor of any new construction or improvements which could not be paid for out of toll revenue.

    I would go one step further and favor auctioning off the entire highway system to private contractors. Highways are the perfect investment vehicle for pensions and insurance companies – longterm with a predictable revenue stream. A purely private highway system would be optimized for speed, safety and profit. The urban highways and freeways we have currently function according to any factor but speed, safety and profit.

  9. Houston’s west loop (610) has been horrible for years. The last one of these lists I saw had the loop and two stretches in LA as the top 3 so I think their criteria is quite a bit different.

  10. Just on shuttle launch day? Colonial Drive traffic sucked every day. Okay, maybe it didn’t extend all the way to Titusville/Tampa most days, but I lived in Orlando and worked on Colonial Drive a block from downtown. [/mistywatercoloredmem’ries]

  11. I simply do not believe the claim that someone changing lanes at 55 mph causes people somewhere behind them to have to stop.

    For a start, if anything bad happens then it’s the guy behind who panics and slams on the brakes. That’s totally unnecessary. There was a gap for the car to move into, there’s just a smaller gap after. Maybe the car behind him wants to get a bigger gap back, but that’s just a matter of *easing* off *briefly* and then resuming the same speed again.

    The biggest problem I see is people not maintaining a constant gap to the car in front. This is especially true when traffic is accelerating. There is always someone who doesn’t accelerate adequately and lets a gap of 100m or more open between him and the car in front. *That’s* what causes congestion for everyone behind.

  12. In Houston, I also learned the flaw of taking away travelling lanes too early, such as I-45 South going from 4 lanes to 3, 5 miles before you get to NASA Parkway exit.

    That’s a bad section of road, but not by design; it’s just an artifact of doing freeway expansions segment-by-segment, in a piecemeal fashion.

    The only thing more annoying is I-45 heading North just before I-610 south where the lane drops into an exit only, so that people rush along the feeder to merge back in a 1/2 mile up the road.

    Now, left-hand exits like that one (and at I-45 northbound at US-59) *are* designed that way, and I agree they’re the worst design flaws in the Houston system. They force people to crowd right in order to stay on the freeway, and the mainlanes back up so much that people “cheat” onto the exit lanes and then merge back at the last second.

  13. Now, left-hand exits like that one (and at I-45 northbound at US-59) *are* designed that way,

    I was referring to the Broadway exit. It’s on the right hand side, along with the feeder. But otherwise, yes, Houston’s habit of left exits is also a problem, but they are being phased out.

  14. The lane you’re in should not ever suddenly become an exit only lane. It should always be a new lane. The entrance lane should be a new lane that continues rather than merge. The leftmost highspeed lanes should merge when lanes need to be reduced; if this causes traffic to slow they know they need to have those lanes continue and merge later. This clearly tells managers where to focus. Yes this will cause people to regularly have to change lanes to the right (rather than the left which is the blind side) but will tend to move traffic away from both the enter and exit lanes.

    When a freeway spits there should be adequate notification so people can make an orderly migration to the correct lanes.

  15. Pretty lame infographic. The cause of traffic jams (of the spontaneous sort, anyway) is both simple and intuitive. A road can carry more traffic at a high speed than at a lower speed. Therefore in heavy traffic, it will easily slip into a metastable state where more vehicles are zipping along at (say) 60 mph than the same road could handle at 50 mph. From there, any small local perturbation *must* cause a cascading slow-down. The particular cause of the perturbation is not especially illuminating, nor is any gobbledygook about “the butterfly effect” or “invisible waves.”

    This trap will spring whether the drivers are idiots or geniuses.

  16. Art is right; however, the design can mitigate some of that. You’ve got two problems to deal with… slow downs and lane changes. Slow downs are not the big problem (and can be caused by nothing more than rubber necking.)

    Lane changes (and merging) are the big problem. By moving traffic away from the entry and exit lanes you reduce the amount of traffic blocking lane changes. Merging is easier in the high speed lanes where traffic is farther apart. Only with saturation would the merging high speed lanes slow down. Vehicles entering could only slow down vehicles entering behind them rather than any already on the freeway which actually helps the situation. No stop before entering lights needed.

    The high speed merge is then the only place that can start a parking lot which is the best place for it to be. There is even a fix for that, but it would be cheaper to just extend the lanes. The fix would be instead of merging take the left lane either under or over to a new right lane somewhere between entrance or exits. This does have the advantage that if you can’t for any reason get to an exit lane, you absolutely will be able a few exits down the road.

    For traffic accidents you mount a vaporizing laser on the hood…

  17. Staying serious, you could also provide emergency exits on the left at the merge points that would have speed bumps to discourage use unless there is congestion.

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