Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Pittsburgh Bus Bunching (2016)

bunching.github.io

Post reply on HN
Print view View original

41–50 of 64 posts

Re: Pittsburgh Bus Bunching (2016)

#41

Post by princekolt »

remarkEon wrote: post #16
cup-of-tea wrote: post #12

Earlier quoted context omitted.

Do they really stop everywhere unconditionally? In the UK almost all stops are by request, for both boarding and alighting.

As another comment noted, even if the stops aren’t unconditional the probability that no one will pull the cord for any particular stop on a crowded bus is near zero.

This assumes all stops are equally popular, but that's very unlikely.

I suspect a lot of bunching is caused by buses having to perform complicated manoeuvres around car traffic because of poor stop positioning. In Barcelona what many lines do is skip stops right before left-hand turns (the line isn't even listed at that stop). This way the bus can switch lanes well ahead of time and avoid having to wait for traffic to go though all lanes. This works because most lines stop every two blocks, so you never have to walk too far for the next stop.

Re: Pittsburgh Bus Bunching (2016)

#42

Post by cimmanom »

andreareina wrote: post #34
remarkEon wrote: post #18

Love this. I’ve experienced bus bunching in several cities at this point (LA, DC, and now Seattle). It seems to be a known failure mode of metro transit planning. First step is understanding what your problem space looks like. Curious to know what anyone here thinks could be a solution. I doubt skipping stops is one. I suspect that speed controls are probably the way to go. Edit: kudos to doing this in R. I’ve done o…

Disclaimer: not a transportation engineer. I wonder what it would look like if departure times were enforced in the don't-leave-before direction. Then giving enough time between scheduled stops that e.g. 90% of buses traveling that stretch can make it in time for that day/time combination . I realize that doesn't mean that 90% of trips will be on-time due to how failures will cascade, but it should eventually catch u…

As a bus rider whose drivers on one route sometimes do this, I loathe it.

The problem is that the route timing is designed for a specific traffic and ridership level. The actual time to run the route can vary by a factor of 3 or more depending on whether it’s before, during, or after rush hour.

The route timing is designed for after rush hour traffic levels, when it takes about 45-50 min to travel from my stop to my office stop. During rush hour, this trip can take 90 minutes. Before rush hour, it can take 20 on a good day.

So now, if I leave before rush hour, a commute that could be 20 minutes becomes 50 minutes. On a bus that is scheduled to arrive every 7 minutes - so bunching means waiting 15-20 minutes for a bus: LESS commuter time wasted by bunching than is spent sticking strictly to the schedule.

On buses that run even more frequently (one every 2-3 or 3-5 min during rush hour), this would be ridiculous. People aren’t catching the bus on a schedule - they just walk out the door whenever they’re ready, and expect a bus to turn up within a few minutes.

On a bus that’s scheduled to run once every 20 min (and you can wait an hour for a bus if they bunch), people are more invested in the schedule. I don’t actually trust the schedule at all unless within a few stops of the start of the route, and usually use the “just walk out the door” method anyway; but would appreciate and use the schedule if it were reliable.

So: as a bus rider I might support this, but they would have to fix the schedules. Create and enforce bus lanes. Run more buses - so that even when you get more riders than usual they can carry all the passengers at rush hour without being so packed that it takes 5 min to cram each new passenger aboard and half the bus has to debark to let someone off the middle. Then a little bit of traffic is less likely to create bunching.

Re: Pittsburgh Bus Bunching (2016)

#43

Post by cimmanom »

arendtio wrote: post #20

> how do we make this better? Just teach the bus drivers to let the empty busses overtake the crowded one. It won't solve the pauses when there will be no bus coming, but at least it increases the passenger comfort by a good margin and the average speed by which the bunch travels increases too.

They already do that in NYC. It doesn’t help because the following stops are full of extra passengers and the crowds on the buses quickly equalize while they remain bunched.

Re: Pittsburgh Bus Bunching (2016)

#44

Post by cimmanom »

paulsutter wrote: post #5

Naive question: when buses are bunching, can't the front bus skip stops that are not needed for dropoffs? (the driver would have to announce that passengers need to request their stops of course).

Aside from infuriating the waiting passengers at those stops... my experience is that a packed bus will have someone getting off at every single stop anyway.

Re: Pittsburgh Bus Bunching (2016)

#45

Post by andreareina »

cimmanom wrote: post #42
andreareina wrote: post #34

Earlier quoted context omitted.

Disclaimer: not a transportation engineer. I wonder what it would look like if departure times were enforced in the don't-leave-before direction. Then giving enough time between scheduled stops that e.g. 90% of buses traveling that stretch can make it in time for that day/time combination . I realize that doesn't mean that 90% of trips will be on-time due to how failures will cascade, but it should eventually catch u…

As a bus rider whose drivers on one route sometimes do this, I loathe it. The problem is that the route timing is designed for a specific traffic and ridership level. The actual time to run the route can vary by a factor of 3 or more depending on whether it’s before, during, or after rush hour. The route timing is designed for after rush hour traffic levels, when it takes about 45-50 min to travel from my stop to my…

I probably didn't do a good job of explaining it, but fixing the schedule was part of the suggestion. So for your example, rush hour timing would allow ~50 minutes between your stops, then after that only 20 minutes.

Re: Pittsburgh Bus Bunching (2016)

#46

Post by cimmanom »

kingosticks wrote: post #35
remarkEon wrote: post #16

Earlier quoted context omitted.

As another comment noted, even if the stops aren’t unconditional the probability that no one will pull the cord for any particular stop on a crowded bus is near zero.

But then it's a simple case of the front bus not letting anyone on (only opens it's rear doors). Everyone then gets on the 2nd bus. The people become spread out between the buses and the probability of not always needing to stop increases. That does obviously only work where your bus design allows it and also to some extent, your drivers being wise to it.

And the passengers not being idiots who feel entitled to exit through whichever door is nearer their ultimate destination. Also the infuriated passengers who’ve been waiting for half an hour or more not taking bricks and bats to the driver’s window.

Re: Pittsburgh Bus Bunching (2016)

#47

Post by afpx »

remarkEon wrote: post #18

Love this. I’ve experienced bus bunching in several cities at this point (LA, DC, and now Seattle). It seems to be a known failure mode of metro transit planning. First step is understanding what your problem space looks like. Curious to know what anyone here thinks could be a solution. I doubt skipping stops is one. I suspect that speed controls are probably the way to go. Edit: kudos to doing this in R. I’ve done o…

I don’t see this often in SF (at least on the E-W routes). Lots of factors though: overcapacity, mass-transit friendly population, express buses, sparse car traffic, linear routes, etc.

Re: Pittsburgh Bus Bunching (2016)

#48

Post by hhmc »

arendtio wrote: post #20

> how do we make this better? Just teach the bus drivers to let the empty busses overtake the crowded one. It won't solve the pauses when there will be no bus coming, but at least it increases the passenger comfort by a good margin and the average speed by which the bunch travels increases too.

Another potential solution during rush hour would be route splitting - each alternating bus on the route is assigned to stop at even/odd stops (e.g. bus 1 stops at 1/3/5.., bus 2 stop at 2/4/6.., 3 at 1/3/5..). This assumes that the extra walking distance between stops isn't too unacceptable (and has some issues for people with disabilities).

Socialising the idea to the passengers is also probably difficult.

Re: Pittsburgh Bus Bunching (2016)

#49

Post by mnw21cam »

ISL wrote: post #6
paulsutter wrote: post #5

Naive question: when buses are bunching, can't the front bus skip stops that are not needed for dropoffs? (the driver would have to announce that passengers need to request their stops of course).

The challenge is arranging for those at the stop to understand what's going on. It is disconcerting to have the #75 bus go past without stopping when you're waiting for a #75 bus.

Someone I know was standing at a bus stop on the phone to me, when the expected bus sailed straight past without stopping. This person then started running after the bus and shouting, trying to get its attention to make it stop. This meant that when the next bus came along 1 minute later, they were not at a bus stop, and that one went straight past as well. All while I was trying to tell them that the only reason a bus would go straight past is if there is another one just behind it, and to just sit tight at the bus stop. He/she/it was not in the slightest bit amused.

Re: Pittsburgh Bus Bunching (2016)

#50

Post by francisofascii »

remarkEon wrote: post #18

Love this. I’ve experienced bus bunching in several cities at this point (LA, DC, and now Seattle). It seems to be a known failure mode of metro transit planning. First step is understanding what your problem space looks like. Curious to know what anyone here thinks could be a solution. I doubt skipping stops is one. I suspect that speed controls are probably the way to go. Edit: kudos to doing this in R. I’ve done o…

Buses are typically late due to variations in traffic. The solution is to prioritize bus traffic. Use dedicated bus lanes. Cars could drive in the bus lane, but must pull over or switch lanes if a bus is approaching. Traffic signals switch to green when a bus is approaching.
Post reply on HN