WBEZ tries to explain CTA bus bunching - a mysterious phenomenon

Since the first bus rolled down the streets of ancient Rome, transportation experts have struggled to explain the mysterious phenomenon called bus bunching.

And now WBEZ Radio has taken a shot at it.

Since WBEZ's story was posted last week, a number of friends have emailed it or posted it on their Facebook wall.

Here are some salient facts and insights from the story.

  • Bus bunching is ninth on the Chicago Transit Authority complaint list, the subject of around 2 percent of all calls.
  • According to CTA performance metrics, only around 3 percent of bus trips experience bunching, which the agency defines as a gap of less than 60 seconds between buses at a stop.

Now,these particular facts are quite shocking to me, considering all the talk about bunching and the angst and anger around the subject.

  • "Minor disturbances" such as a double-parked car can lead to bunched buses.
  • Drivers can do a few things on their own to stop bus bunching, such as leapfrogging the driver in front of them or skipping unneeded stops.

The "minor disturbances" make sense. What's not mentioned is that passengers also cause bunching, often through no fault of their own. For instance, the boarding of a wheelchair-bound passenger can cause delays down the road.

  • As a system, buses by design are set up to bunch, according to one expert. “A bus system by nature has bad dynamics,” according to University of Chicago Professor Donald Eisenstein. “Left on its own, buses will bunch.”
  • Big gaps between buses, he said, will get bigger, while small gaps will shrink. This reality makes it almost impossible to eliminate bunching on a route unless there’s a lot of time between buses.<

Now, those are some interesting observations. It's almost saying we will never solve the problem of bus bunching.

Here's how the CTA explains bunching.

And, the top five most-bunched buses are:

  • #49 Western, with 5.6 percent bunched boardings
  • #22 Clark, 5.4 percent
  • #9 Ashland, 4.9 percent
  • #66 Chicago, 4.8 percent
  • #79 79th Street, 3.6 percent

Happy bunching!

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  • What would be more interesting are the stats for rush hour bunching.
    Last week I saw on Bus Tracker that there were 6 NB Clark buses in a 3/4 mile stretch from Granville to Pratt.
    It was at the end of the afternoon rush, maybe 7PM.
    There was over a 30 minute wait for a SB Clark bus at the same time.
    Four of those buses disappeared from Bus Tracker, when they got to Howard, meaning they went straight back to North Park Garage.

  • In reply to ScooterLibbby:

    Oh yeah, I've had long waits for a southbound Clark bus at the beginning of the run from Howard. One time I sat and sat while the 22 display from buses discharging passengers at Howard turned in to "North Park Garage" for about 4 buses in a row. Apparently that is the priority, to meet a quota of buses going back to North Park. After about half an hour I found a supervisor and pointed out that the would-be passengers were not getting any buses. He instructed a bus driver to be a 22 and pick up the people waiting at the stop. The driver then proceeded to leave without picking us up. That is when I realized that while many drivers may have a thought in their brains and do their jobs, it is entirely possible for one not to.

  • In reply to CCWriter:

    When there was a supervisor at Howard & no buses available for SB Clark, he would often tell a driver going back to North Park to change his destination sign to Clark/Foster or Clark/Devon & send the bus out to at least reduce delays for that stretch.
    There's no more street corner supervisors & it's a major reason for the increase in bunching now.
    The same went for the Clark/Devon Supervisor. He would take three buses & combine them into two & flip one back SB.
    That never happens anymore.

    You would think there must be some common sense at the secret Racine Ave. control center that when they see bunching near a turn around, that they would call the drivers on the radio & have them combine & then have one flip in the other direction.
    This is a management problem that's being totally ignored!

  • Combination of using CTA statistics (instead of other media outlets getting out there with a stopwatch) and WTTW saying that it was cured, so there is the question which public media outlet you can believe.

  • As I approached the corner of Chicago and Larrabee this morning to catch the eastbound #66, there were two buses at the bus stop (east of the intersection), and two more waiting at the traffic light. WTF. I was lucky that the driver of the 4th bus saw me waving to him, and he waiting for me.

    I totally agree that as the buses bunch, it gets worse. The ones in the front are generally packed, and it takes longer to unload/load, allowing the trailing bus to get closer.

  • It's interesting to realize that many situations involving behavior, choice and motivation have dynamics like physics, and you can't solve them without taking behavior, choice and motivation into account.

    One problem in attempting to compensate for bunching is that some drivers will bypass passengers waiting at a stop, or attempt to do so. It is understandably frustrating for those passengers. They feel that the fact they are already late is not taken into account. They worry that the drivers don't care about them. There is little evidence to show they are wrong about those things. If the CTA could address those concerns in real time to the actual passengers, it might help.

  • In reply to CCWriter:

    NY buses had the policy (at least in the 1980s) of putting on the destination sign "next bus please."

    There are ways of dealing with it, but apparently CTA assumes that everyone has a smart phone with BusTracker on it, and sees that the next bus will be in 20, 22, and 24 minutes, while the assumption should be that the supervisor has BusTracker on a laptop and is actually doing something to maintain service on the street.

  • In reply to jack:

    A handful of bus stops have Bus Tracker data displayed, so no smartphone required. Of course, this is a tiny fraction of the total number of stops. I completely agree that a 'Next Bus Please' sign would be the least they could do. The El often runs express to skip stops, and the combination of flashing white lights, the 'Express' sign, and the blaring horn makes it quite clear that the train is skipping stops.

  • In reply to SpinyNorman:

    I was going to mention the Express L, but forgot about that until you did. Apparently CTA bus and rail operations don't speak to each other.

  • In reply to jack:

    There is a basic problem with running a bus express, however. The trains have a PA system to notify riders that the train will be running express, allowing riders to exit if their stop will be slipped.

    OTOH, the buses don't appear to have functional PA systems, and some drivers don't have the lung capacity to shout loud enough so the riders in the back can hear. One would think that the information boards could be used, but many of the buses lack working information boards.

  • In reply to SpinyNorman:

    A functioning PA system (usually there is a microphone on a flexible connector on the left side of a bus's windshield) has been an ADA requirement since 1990.

    Anyway, the issue on bus is not picking up people than not dropping them off. I suppose that a driver could tell the passengers that he isn't stopping and to take the follower, but that would cause a riot.

  • In reply to jack:

    I thought they got rid of the microphones when they put in the automated stop announcements. A year or so ago, I was on a hastily created special bus run taking people downtown, when everyone had to get off at Belmont because of the Red Line derailment. The driver could not tell passengers where the bus was going. It was that experience that prompted me to daydream of putting in the stocks in Daley Plaza whoever took the microphones out of the buses.

  • In reply to CCWriter:

    I was on a 147 today & it had a microphone, the driver used it.
    It was a fairly new 4300, though.

  • In reply to CCWriter:

    Scooter, there's no reply button on your comment about the microphone on a new 4300. But I must conclude I got through to somebody with the choice between a banana cream pie and a rotten tomato in the face. If they keep it up with installing microphones, it'll earn an upgrade to chocolate. Then it'll just be a matter of instructing the drivers to actually use 'em when there is something we ought to know.

  • In reply to CCWriter:

    The reason for the Mr. CTA system is that the law is either announce the stops or use an automated system to do so. Since there was no way to assure that the operators called out the stops (unlike in the 1970s when then did), Mr. CTA arrived.

    Maybe that one bus didn't have a working system, or maybe that driver was typical.

  • In reply to jack:

    Jack, re your comment about no microphone being an exception. I don't think so, because I have been on other buses where there was something important going on, for instance, you all need to get off...or this bus is no longer going to Union Station...where the driver did not make an amplified announcement but said it only to those within earshot. Most of the passengers cannot hear and they only know something is going on--not what. Believe me. It has been years since I have heard a microphone announcement on a bus.

  • In reply to CCWriter:

    The specifications for the 7900 series bus (which are the standard procurement guidelines used since 1998) say at page 168:

    "A public address system shall be provided on each bus for facilitating radio system and driver-originated announcements to passengers. A public address system that complies with the ADA requirements of 49 CFR Part 38.35 and enables the operator to address passengers either inside or outside the bus."

    The regulation is here although it uses the term "or."

    Thus, if the microphone is missing, I suggest either filing a complaint with the Federal Transit Administration, or since it is required in the specifications, with the Inspector General (ha,ha, I just made a funny with respect to the IG).

  • In reply to CCWriter:

    Jack, sorry, again the reply button to your latest comment isn't working. Surely you realize that just because an old procurement guideline says something doesn't mean it's complied with. Rather than filing a complaint with a bureaucracy, pie in the face (after proper sentencing of course) is more my style.

  • In reply to CCWriter:

    I was not citing an old guideline. I was citing a specification dated 2012 for buses being delivered in 2014.

    The only reference to 1998 is that the guideline has been fairly consistent since the standard one was developed.

  • Way to skew the stats, CTA - define "bunching" as 60 seconds! Four buses within 6-8 minutes followed by a 27 minute gap, then repeat. Sure felt like bunching to me on Monday, but averaging 120 seconds apart saved their bacon.

    Frustrating as it is to watch the bus pass my stop, it always seems to me that some form of express/stop-skipping would alleviaalleviaslowing effect of the accumulating waiting passengers.

  • Wow, this just happened to me yesterday. Three #28s arrived at my bus stop, along with 2 #6s. Luckily, the first one that came was an accordion bus, and I was able to get a seat. That 60-second thing on the CTA website is a bunch of BS. The problem with bunching is that all the drivers want to play "follow the leader" instead of driving around, and going to the next stop. This saves time, but these drivers don't care. I never saw the other 2 #28s until I got off at my stop downtown--not once did they move ahead. And blaming the disabled--that's low. The ramps on the buses now hardly take any time to go up and back--unlike those antiquated ones on the older buses from 20, 25 years ago that would always get stuck.

  • In reply to mulder42:

    'Agree about the wheelchairs. I primarily blame the Ventra card. Boarding times have definitely lengthened since the introduction of Ventra, as the readers are sooooo dang slow compared to the old Chicago Card Plus.

    Riders using cash also gum up the works, at least the ones who don't have it out and ready when they board.

    Lastly, a CTA thread wouldn't be complete without a ding at the folks with Hummer-sized strollers, as they try to maneuver the beasts in the isle.

  • OK, so what's the solution? Priority traffic light timing for buses? Stop skipping? Faster loading times?

    I'm looking at Bus Tracker for the #66. There are 4 eastbound buses between Larrabee and LaSalle St, a stretch of 5 blocks. The next bus is back at Leavitt.

  • In reply to SpinyNorman:

    1. Signal priority for buses.
    2. Demand that Cubic fix Ventra, which is a total failure. It should read correctly every single time & withing a half second. It should also read the Ride Free cards instantly. I see it time & time again, that these cards aren't read properly & must be retapped. Change the damned software so the farebox doesn't need to communicate with the server by cell tower for these cards. Otherwise the CTA should sue Cubic for every cent spent on this mistake, plus treble damages. Then install a new system similar to the old system. That works everywhere else in the world!
    3. Fewer stops, especially on Sheridan & the Inner Drive south of Irving Park.
    4. Make the kneeling of the bus, automatic with the door opening. Too many drivers won't do it unless you ask. It definitely makes loading & unloading faster.
    5. Move all stops to the far side corners, unless there's a specific reason not to. That, in conjunction with signal priority will speed it up as the entire bus, can get to the curb.
    6. Install that special turn signal light on the left rear of the bus. Along with the law that requires cars to stop & let the bus merge immediately, that would speed up the buses. It was tried in California a few years ago, but they ended it for unknown reasons.
    Use bus mounted cameras to give out the $100 tickets for not allowing the merge.
    7. Try, but it will be difficult to educate the stupid among us how to board correctly. Cash payers go last, as do those who have physical problems, as they are just slower. Also get the young & healthy to not use the seats in front marked for the seniors & handicapped. And get those damned strollers out of the aisle! Make the drivers tell people not to stand near the front or in the exit door [Exitdor, was the CTA's attempt at copying Colonel McCormick's spelling reforms in the 1950s].
    8. Get rid of all stop signs on bus routes, except those where the bus uses a side street, such a Berwyn, from Broadway to Sheridan. The delays on Clark, from Montrose to Bryn Mawr are insane & solely due to the stop signs. Put up those Pedestrians Have the Right of Way to cross signs instead & enforce them. Stop signs also increase pollution, because they cause all vehicles to stop, even at 3AM when there's no one out there.

  • In reply to ScooterLibbby:

    Slightly OT, but I can't figure out why the city has so many 4-way stops, such as on Halsted south of 95th. The way that stretch looks, that's half the intersections where they can't install red light cameras.

  • In reply to ScooterLibbby:

    I somewhat disagree with #5. 'Nothing like getting caught at the red light, and sitting there waiting for a green. 'Could be using that time to discharge.

    Perhaps what is needed is a bit of flexibility. If the bus is caught by the red light, allow the driver to discharge passengers only. The boarding passengers will get on at the stop on the other side of the intersection. I see #66 drivers do this on occasion at Chicago and Larrabee. It certainly speeds boarding, as the passengers have already discharged at the traffic light. Of course, I assume this is against the official operating rules.

    'Couldn't agree more about the f*cking stop signs. Either get rid of them, or install a traffic light.

    Yeah, I don't care what the contract states, the Ventra system is too damn slow. One thing I would do would be to move the readers. The current location washes out the display, making it difficult to see if the pass was accepted.

  • In reply to SpinyNorman:

    The theory behind traffic signal preemption is that an approaching bus gets the green and can stop on the far side.

    Of course, with Emanuel crying that the RTA won't pay to replace all the traffic lights in the city (which are alleged to be too obsolete to take TSP) it may be a moot point.

  • In reply to jack:

    OK, that makes sense if preemption is in place. The other benefit is that it doesn't block cars making right hand turns, given that turning in front of the bus is supposed to be illegal. (Funny, I see it all the time and there's never a cop around).

    Another thing that would help would be for the city to aggressively ticket and tow cars parked in the bus stops, which forces the buses to stop in the middle of the street. For a city that is on the verge of bankruptcy, they sure leave a lot of revenue on the table in the form of uncollected fines. Hell, drive down any major street during rush hour and count the number of cars parked in the rush-hour no parking zones. If I was the mayor, I'd hire an army of tow trucks, and flood the streets prior to rush hour.

  • In reply to SpinyNorman:

    You're right, Spiny. The Ventra system is too slow. Why is it that 99% of the time, if I'm the first person boarding, I have to tap my card 2 or 3 or maybe even four (just for kicks!) times to get that stupid box to read it right? This is totally frustrating. If I'm not first, I can zip right through, no problem. I wish someone could fix that. This is the main problem for slow buses.

  • In reply to mulder42:

    I meant jack--sorry. Typing really fast, and I didn't read it right. :(

  • In reply to mulder42:

    OK--I was replying to Spiny.

    Kevin, can you delete these replies? I thought we could delete, but I'm not seeing it here.

  • In reply to mulder42:

    A big part of the problem, as ScooterLibby mentions, is the requirement for the Ventra system to be continuously connected via wireless network. There are numerous areas of the city with poor cellular signals, and boarding in these areas can take 2 or 3 taps.

    I'd redesign the system to have a very short timeout, e.g. 250 milliseconds, and if no response was received from the central server, then the rider gets a green 'Go', regardless of their account status. The probability of having a) an invalid card/account, and b) a bad wireless signal, are quite low. The CTA wouldn't be giving out that many free rides.

    The priority has to be getting the riders boarded quickly, not delaying 99% of your riders to ensure you don't allow the 1% of riders with invalid cards to get a free one-time pass.

  • In reply to SpinyNorman:

    There are a few drivers on every route that will let passengers off on the near corner, when the stop is on the far corner, if the bus is stuck at a red light.
    But there are always the sticklers for the rules who won't. The only rule should be, if the bus is at a red light & is also at the curb, then the driver is allowed to open the doors for anyone wanting to get off.

    There is one route I ride where almost every driver will let you off on the near side due to a red light, but I won't mention it, because then the CTA will crack down on them for doing so. They do it so people can catch the bus on the intersecting street.

  • In reply to ScooterLibbby:

    That's been my experience, too. I guess what's needed is a "conditional" bus stop sign at the light, allowing for discharge when the light is red, and the bus is at the curb, as you note.

  • In reply to SpinyNorman:

    There was the theory of the (B)RT system on which Mare Daley missed the deadline, i.e. $180 some million for 4 routes.

    Or the current theory of ban all left turns on Ashland and spend $160 million for a fake BRT there.

    They have been messing with signal preemption on Western for about 6 years, and it is listed as the more messed up route.

    Then they mess around with taking articulated buses on and off routes such as 79. Apparently adding them to 66 didn't take care of the bunching problem.

    Add in that Rodriguez took the "extremely progressive" step of eliminating the X routes, and no one brought them back. Again, Western is the most messed up route, Ashland is third.

    Maybe Clark is too narrow to do anything about, but Western and Ashland are not (at least at the moment).

    You can see that CTA has no clue.

  • In reply to jack:

    Articulated buses on the 66 didn't cure the bunching problem, but it sure has helped the capacity problem. I can now board the bus most days without worrying about finding a spot to stand. Previously, the buses were packed like sardines, and it wasn't uncommon to have to wait for the following bus.

  • Kevin, or others, what is your opinion of buses that run races, or leap frogging?

  • In reply to ibilldavis:

    What do you mean by run races?

  • In reply to SpinyNorman:

    Buses of the same route that pass each other.

  • In reply to ibilldavis:

    I don't have a problem with it, but of course the real issue is the buses bunching in the 1st place.

  • In reply to ibilldavis:

    They're not "running races"--they're going around the bus in front to save time, and not have buses piling up behind each other, playing "follow the leader" like I said in my post on Thursday. If they do that, then nobody goes anywhere. The only time they should follow the lead bus is when passenger(s) want to get off.

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