Nice interactive chart and map that shows bus bunching on Pittsburgh’s busiest bus corridors. I’d love to see something like this for Seattle.

27 Replies to “Sunday Open Thread: Pittsburgh Bus Bunching”

  1. A few weeks ago I found myself at the head of a four bus bunch on the F when they were down to 15 minute headways. I wanted to get a picture of all four buses crowded around the final stop, but the driver refused to go around the corner to get there. He forced everyone off early. Another driver of the buses behind also didn’t go around the corner, so it left just the usual two at the terminal.

  2. Bus bunching is a complex topic. Simple arrival data at one point can’t explain things very well.

    First, a comparison is needed at several points along a route. Is it because buses start the route in bunches or because it develops while on the route? Is it because of loading delays (including extra wheelchair or bicycle loading time or maybe event surges like schools letting out), traffic delays, train track disruptions (like in SODO) or signal delays (SDOT’s new pedestrian signals seem to ignore approaching buses — especially when they malfunction)?

    There are plenty of possible reasons that buses get bunched. I’ve even heard stories in othe cities that drivers who are friends will leave by driving buses in tandem one right behind the other.

    1. I would guess that loading delays are the primary cause of bus bunching. It doesn’t make sense for buses to leave at the same time. Traffic delays would tend to keep buses a ways behind each other, except in rare circumstances. If a bus has its own lane right up to a bridge, and the bridge opens, then I could see two buses being back to back. But other than that, it seems rare.

      But it is easy to see how delays in boarding can cause bunching. One vehicle is stopping a lot, while the other isn’t. That is why Philadelphia is looking into adding “BRT”. That could mean nothing more than off board payment — but that itself will speed boarding, and thus reduce bunching. But it won’t necessarily eliminate it. If the first bus stops a lot, and the second bus doesn’t, then the second bus will catch up to the first, even if the first is quick to load. Even subway systems can “bunch” in the sense that trains are delayed because of other trains. They don’t run right behind the other (because it would be too risky) but they are essentially bunched. Unless you have a very tight system (with doors opening and closing at exactly the same time) or a short system, you are likely to get some form of bunching if you have very big loads. The best you can do is reduce it, and off board payment, as well as faster running (essentially making the lines shorter) is a good way to do so. Sounds like Philadelphia may be doing that, which would be great.

    2. I depend on bunching during weekdays. I see a lot of people at my stop, and I will routinely take the second bus. While OnebusAway and the new Metro SMS service arrival times tend to be undependable, the sequence of the buses is pretty good.

      I’ve been noticing a number of other riders looking for the bunched bus before they board.

      1. I boarded the second bus in a bunch, and the driver asked me why. I responded that I wanted to give some love to the second bus.

    3. I’m very weary of any scheme’s to prevent bus hunching by artificially slowing buses down with excessively padded timetables. It just guarantees that every trip is going to be slow, even when there’s no traffic, does nothing to address the double wait for the first bus in the bunch, and makes wait times unpredictable when OBA says the bus is early, since you have no idea whether any particular bus driver is going to wait or not wait at any given stop.

      I’d prefer to have the buses just drive. If you miss it, pull out OBA and see when the next one is coming. Most likely, the route is frequent, and the next bus is early too. If the wait is too long, summon a Lyft or Uber, or, if the distance is short, just walk. In the modern world, missing a connection because a bus is early doesn’t really mean standing at the bus stop for half an hour anymore.

      1. At one stop perhaps not, but on multi-leg trips it can easily lead to a cumulative increase of a half hour or more as missing connections cascade on down your route.

      2. This is really an easy one. Have drivers forget the schedule and run on “headways”. Distance between their front bumper and your leader’s back one. Any driver habitually staying close to run empty while their leader takes all the passengers? That’s what talks with Base Chiefs are for.


      3. Chicago has addressed some of the scheduling problems relating to bunching by deleting many schedule timepoints, allowing early arrivals at the terminal and the last one or two timepoints, and using AVL data to identify early terminal departures. This has largely eliminated the frustration of watching your bus wait just outside the terminal so the operator doesn’t get busted for an early arrival.

        Those are relatively easy fixes. It’s much harder to reschedule routes to allow enough running time to account for slowing traffic. More running time means you have to pay the operator more, and just a few minutes adds up quickly.

  3. Last week, at the Fremont/34th stop, at about 5:45PM. I saw four (count ’em, four!) #40 buses bunched. My previous visit to that stop was about 2 weeks earlier, at about the same time – there were only 3 #40s bunched that day. The normal headway during peak is 6-8 minutes on that route – 4 bunched buses implies an actual headway of around 25-30 minutes. So much for “frequent service”.

    I agree with Al that there are multiple causes. Some can be, at best, only modestly ameliorated (e.g., wheelchair loading). But, just about all the long litany of fixable delays to buses are seriously implicated. From what I’ve seen, at peak hours, the most prominent problems are traffic-related delays, which can be vastly reduced by enforcement of bus lanes and box-blocking bans, expansion of bus lanes / bus priority / queue jumps, etc.

    Mayor Durkan? Anyone there?

    1. The 40 should be RapidRide. By that I mean it should have off board payment and level boarding for most of the stops. That itself would reduce the bunching. Adding bus lanes and enforcing the ones we have would speed things up, which is valuable in its own right, and certainly wouldn’t hurt when it comes to bus bunching. The 40 is slated for “RapidRide+” treatment ( but apparently the previous administration didn’t allocate enough money for them (oops).

      My hope is that the legislature will allow Seattle (and other cities) to raise their own taxes (with or without a vote) to allocate money for projects like this. The arguments against it make sense when it comes to schools (the idea being that rich districts will have great schools but poor ones won’t) but make no sense for transit (where state money makes up a tiny sliver of the funding). There is no statewide effort to provide good transit to everyone as there is with schools (nor a state constitutional mandate). The restrictions on Seattle (and other cities) are just anti-tax zealots who don’t believe in giving people the right to tax themselves. Hopefully the state legislature — in what looks like an election that will result in a lot more progressives — will correct the problem next term.

    2. Have supervisors at point where congestion starts to order bunched buses to form their own platoon, as if coupled. And put out word about this mode to both drivers and passengers. Like Route 41 should do at rush hour and doesn’t.

      But major necessary adjustment: By a card someplace else. Zones Proof of Payment,so on-board fare inspection minimal, many polite requests and reminders. By the balance sheet, time saved will pay for itself.


  4. Hey all, moving to Seattle soon from SF and renting a room in house on Kirkwood about half a block south of a bar called Leny’s on 56th. I don’t know city at all but I’ll be living car-free and was wondering what route people would recommend getting to my job in Denny Triangle. The Rapid E line is a bit of a trek but there are local buses nearby. Also, it looks like light rail isn’t really an option since the last stop is pretty far from where I am.

    Overall since I’ll largely be relying on Transit I was wondering if anyone could give me the lay of the land for the routes I should know, not just for work but for grocery shopping, restaurants/bars, other errands, etc. Thanks much in advance!

    1. The 62 goes practically door to door and is full-time frequent.

      Going to UW Station would be a ten-minute walk to 45th and a fifteen-minute ride on the 44 (or longer in traffic).When U-District station opens in 2021 it will be much better.

      1. Yeah, what Mike said. Here is a map of the bus routes (and light rail line) for the city: . The thicker the line, the more frequent it is. I find that gives me a great overview of what is a fairly complex set of buses in the city. Metro has information about individual routes (like the 62 — as well as their own maps, but I only check those out when traveling outside Seattle (I find Oran’s much easier to read). In my opinion, Google also does a pretty good job when it comes to mapping out a transit route. Just put in starting and ending location (as well as time) and you can see the most common options. I use the transit app called “One Bus Away” to check on buses while at a bus stop, but I haven’t tried the other apps.

    2. Some random comments:

      Seattle blocks are very small. The rule of thumb is that 20 blocks is one mile. Don’t let a street map fool you into thinking that walking 10 blocks is difficult — unless you have a mobility issue or if there is a steep slope (which Seattle has, like San Francisco). A Seattle block is about 60 or 70 percent of a San Francisco block in length.

      Bus real-time arrival info is pretty good for a mobile phone. I use the OneBusAway app but there are others. There are occasional reliability issues with it.

      Metro Route 62 will probably be your primary route. It can get delayed in traffic or by the Fremont drawbridge, but you’ll endure it while on a hopefully comfortable bus.

      You can always take Metro Route 44 to the U-District or to the UW station but UW area traffic can be notoriously awful.

      There are small storefront commercial districts nearby. The best is probably Greenlake (east side of the lake) with lots of restaurants and a local upscale grocery (PCC).

      Check with your new employer to see if they offer an Orca card as your transit pass. Employer-sponsored Orca cards are a wildly economically-favorable deal that beats anything around the Bay Area.

      1. North of the Ship Canal it is 20 blocks per mile, or about 3 mins per block for the average human. South of the Ship Canal it is usually 16 blocks per mile, but there is a lot more variation.

        Leny’s is just one of the bars in the area. If you go there, say hello to Big Brian

    3. The 62 goes through many neighborhoods: Fremont, Wallingford, Greenlake, Roosevelt, etc. There’s a lifetime of bars and restaurants among them and you’re right in the middle, although 55th itself has only a couple choices. The nearest supermarkets are QFC in Wallingford and Whole Foods in Roosevelt. If you want even more bars you can take the 44 to Ballard; that’s also where most of the live music in north Seattle is. There’s a movie theater at 45th & Roosevelt. . The Guild 45th in Wallingford is unfortunately closed but you can still see its art deco facade.

    4. I live in the neighborhood. Welcome!

      I wouldn’t necessarily recommend the 62 for a commute downtown. It does get there eventually, but it takes a while, running on slower neighborhood streets through Wallingford and Fremont on the way. You will likely have a quicker overall commute if you walk over to Latona Ave to take the 26X. It takes a much faster path downtown, and runs pretty frequently during peak commute hours (though only once every half hour the rest of the day).

      The RapidRide E line is not rapid enough in comparison to closer buses to be worth the trek.

      For groceries, the 62 would work great for you. It goes right past the QFC in Wallingford, or if fancy organic stuff is more your speed it also gets you pretty close to the PCC east of Green Lake or the Whole Foods in Roosevelt.

      The little commercial area right by your house is often referred to as “Tangletown.” It has several eating/drinking establishments (a brewpub, a sushi restaurant, a hot dog shop, an Indian/Nepali restaurant, a donut shop, a coffee shop, a Japanese bakery, Leny’s Place, and a couple others), as well as a few other businesses (a convenience store, a couple of dentists, a chiropractor, a naturopath, an art gallery).

      South of there on 45th Street is the main commercial strip of the Wallingford neighborhood. You can walk or take the 62 to get there. You’ll find more restaurants there, as well as drug stores, banks, and the QFC supermarket. The 44 bus runs east/west along 45th, and will get you to the University District to the east and Ballard to the west. Both neighborhoods have lots of interesting things to see and do.

  5. On the weekends, why do trolley routes run with diesel buses? I get that some of the buses need to be out of service for cleaning, routine maintenance, etc., but I feel like when I’m in the city on Sunday, trolley buses pretty much disappear.

    1. Usually it’s an interruption in electrical service on the wire, either for wire maintenance or other construction. Sometimes it’s because there is construction that requires a detour that a trolley route cannot take.

      I’ve noticed fewer of these since we got the trolley buses with battery backups, since they can go up to a mile off wire.

  6. Random boarding delays can probably account for two busses raindomly being bunched, but not three or four!

    The thing about traffic congestion and busses is you would think that busses that get stuck in traffic just stay at the same frequency because they all experience the same traffic. However, in congested situations perhaps the more relevant metric is car lengths between busses. Once they get out of the congested area/intersection/event, their car length separation is still the same, but now at the higher speeds you get a situation where multiple busses come together, and the original intended headway is killed.

    I think traffic congestion is more important than boarding delays when it comes to bus bunching. But it is a complex topic and both definitely come in to play, and both are worth improving on!

    1. Traffic induced congestion is only likely to occur when you have a sudden rush of traffic (e. g. a game just ended). A big rush of cars clog up the lane right around the stadium. Traffic is flowing great before then, which means that the buses build up there.

      But that is rare. Look at traffic on the freeway. If I leave 15 minutes after you, I’ll never catch up. It doesn’t matter if you are driving at 3 AM (where there is no traffic) or rush hour. Unless we are driving across the country (or one of us changes lanes) I will always be well behind you. That is because there really is no rush “hour”, it is slow, gradual increase in congestion. The converse is true as well. Traffic doesn’t just disappear at a particular hour — you go a little faster and a little faster until you are moving well again. The same is even more true when you add traffic lights and the slower speeds found in the city.

      On the other hand, it is very easy to see how bus bunching is created with minimal traffic, but slow boarding. A handful of riders fumble with change at a stop, slowing the bus down. That means that the bus is now late (but only by a few seconds) so you pick up a few more passengers. Bit by bit, you are picking up more and more people, while the bus behind you isn’t. The rider that was planning on taking the 5:15 managed to take a 5:05 that was running a couple minutes late. The time difference between the buses shrinks, and that means that the second bus can sometimes skip a stop. Next thing you know, you have bus bunching. That is without anything extraordinary (like a wheelchair ride or a load of tourists asking questions and counting their change). Again, it happens on subways (subway!) where there is no traffic. It is just that you don’t see it (because the train just waits for the other one because of safety). It is really about the boarding.

  7. The worst bunching I’ve seen since moving here 12 years ago was back in the pre-E 358 days (probably around 2011?). My partner and I were waiting at the southbound 45th & Aurora stop at about 6PM. Traffic was unusually light for Aurora. We were waiting for 15 minutes and didn’t see any buses in either direction (IIRC headways were 15 minutes as it was close to peak, but it was before Metro/SDOT really started caring about frequency). We then saw 6 358s going north over the course of less than 10 minutes. Then nothing in either direction for an hour. If we had been smart and had One Bus Away available, maybe we would have walked to the 5, but that was likely to have been as bad as the 358 in those days.

  8. If you wanted to make this for Seattle, where would you get the data?


    Grayson Reim

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