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Why Do Buses Bunch?

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Re: Why Do Buses Bunch?

#71

Post by lenticular »

gordo4 wrote: post #25
aarongolliver wrote: post #14

Earlier quoted context omitted.

Same happens in Seattle (and we have some nice services that show you the GPS locations of all the busses on the route, so you can be pretty sure an empty one is right on its way)

That app was built by a UW student and uses estimated data based on the schedule, as far as I know. It's not accurate... unless things have changed in the last year or so since I moved.

When that app (OneBusAway) first came out, it was extremely accurate. It completely went to crap when Metro took over maintenance.

Re: Why Do Buses Bunch?

#72

Post by tomjakubowski »

thtthings wrote: post #70
adrianmonk wrote: post #26

Would it help to have the trailing bus pass the leading bus when they bunch up? My reasoning: (1) As the article said, full buses move slower because more passengers means more boarding/unboarding time at stops. (2) The lead bus is the fuller, slower one. Slower bus in front means buses get closer together. (3) If one bus passes the other, then you have the faster bus in front and the slower one behind. They should t…

They all don't go to the same destination. They have an overlap of route but all of them go to different destinations. So you cannot just skip a bus stop. You are very rarely if ever going to see the same numbered buses bunched together

Don't overgeneralize. The featured article (simulation, really) is about bunching of buses on the same route, a phenomenon that I, a daily bus commuter in Los Angeles, USA, routinely witness.

Stops on the routes I take are also generally skipped unless someone is waiting at them or a passenger has pulled the cord/pressed the button to request a stop.

Re: Why Do Buses Bunch?

#73

Post by djmips »

umvi wrote: post #30
adrianmonk wrote: post #26

Would it help to have the trailing bus pass the leading bus when they bunch up? My reasoning: (1) As the article said, full buses move slower because more passengers means more boarding/unboarding time at stops. (2) The lead bus is the fuller, slower one. Slower bus in front means buses get closer together. (3) If one bus passes the other, then you have the faster bus in front and the slower one behind. They should t…

You could probably have a computer calculate which stop the trailing bus should jump ahead to. Then you have the trailing bus switch to "out of service" mode (so it doesn't enrage people when it passes a bunch of stops) and skip ahead 4 or 5 stops or whatever the computer decides is optimal.

It would be horrible if the slow bus behind was actually too full to pick up people so you have an empty bus passing stops that the trailing bus will also skip!

Re: Why Do Buses Bunch?

#74

Post by thtthings »

tomjakubowski wrote: post #72
thtthings wrote: post #70

Earlier quoted context omitted.

They all don't go to the same destination. They have an overlap of route but all of them go to different destinations. So you cannot just skip a bus stop. You are very rarely if ever going to see the same numbered buses bunched together

Don't overgeneralize. The featured article (simulation, really) is about bunching of buses on the same route, a phenomenon that I, a daily bus commuter in Los Angeles, USA, routinely witness. Stops on the routes I take are also generally skipped unless someone is waiting at them or a passenger has pulled the cord/pressed the button to request a stop.

I am not overgeneralizing. I am mentioning every use case!

The stops are skipped because no one wants to get out of the bus and there is no one to board it. It has nothing to do with bus bunching.

Here in downtown Vancouver, there are some stops that have 5 different numbered buses making stop. Can they just skip ahead because there are a couple of buses already there at the stop?

To really make this works will have to check 1. Is the bus stopped in front of me the same numbered bus? 2. Does it have enough seats to board people that have lined up?

If yes then lets just not stop.

Re: Why Do Buses Bunch?

#75

Post by tim333 »

inferiorhuman wrote: post #61
tim333 wrote: post #10

Earlier quoted context omitted.

It's mostly been fixed in London. They used to be famous for no busses for 20 mins then 3 at once but they are now controlled by a central computer system which knows all the positions via gps and cell data.

That's fascinating. Are there any writeups on it?

https://en.wikipedia.org/wiki/IBus_(London) is part of it. Also https://www.intelligenttransport.com/transport-articles/688/... http://www.eltis.org/sites/default/files/case-studies/docume...

It's not actually clear if the de-bunching is algorithms or humans:

>Headway information, the time gap between consecutive buses, will be available to a bus driver at all times on a screen so that they can make decisions such as slowing down or speeding up to help maintain a regulated service and stop undesirable ‘bunching’ of buses.

Re: Why Do Buses Bunch?

#76

Post by ambicapter »

massivecali wrote: post #39
kazinator wrote: post #16

Earlier quoted context omitted.

Buses don't stop at unoccupied bus-stops, unless someone dings the bell. The faster bus skipping stops where people are waiting, so they can be picked up by the next bus does work; I've seen it in action.

Which, as a patron who doesn't want to sit for an hour in the sun, is really not acceptable. The bus is not supposed to be in a race, they are supposed to make predictable stops along a predetermined route. Most bus stops I have used in the US dont have covered shelters or enough space for passengers to wait outside of the elements. Usually this means sitting under the overhang of a nearby business. If the bus doesn'…

We're talking about bus bunching here. The bus is skipping your stop because there's an empty one right behind it.

Re: Why Do Buses Bunch?

#78

Post by kuldeep_kap »

adrianmonk wrote: post #26

Would it help to have the trailing bus pass the leading bus when they bunch up? My reasoning: (1) As the article said, full buses move slower because more passengers means more boarding/unboarding time at stops. (2) The lead bus is the fuller, slower one. Slower bus in front means buses get closer together. (3) If one bus passes the other, then you have the faster bus in front and the slower one behind. They should t…

You are forgetting people who would want to get off that stop, so this is may not be an option.

Re: Why Do Buses Bunch?

#79

Post by massivecali »

ambicapter wrote: post #76
massivecali wrote: post #39

Earlier quoted context omitted.

Which, as a patron who doesn't want to sit for an hour in the sun, is really not acceptable. The bus is not supposed to be in a race, they are supposed to make predictable stops along a predetermined route. Most bus stops I have used in the US dont have covered shelters or enough space for passengers to wait outside of the elements. Usually this means sitting under the overhang of a nearby business. If the bus doesn'…

We're talking about bus bunching here. The bus is skipping your stop because there's an empty one right behind it.

This is great in theory, but not in practice. A bus in back sees the bus in front stop so it passes. However the bus in front might be full and only drops off one pasenger while more than one pasenger is waiting to board and are thus denied. Again, simple dismissal of the problem is ignorant of reality.

Re: Why Do Buses Bunch?

#80

Post by zhte415 »

brian_cloutier wrote: post #54

I enjoyed the callout to this when I was reading Google's Percolator paper a few years ago: > The random-scanning approach requires one additional tweak: when it was first deployed we noticed that scanning threads would tend to clump together in a few regions of the table, effectively reducing the parallelism of the scan. This phenomenon is commonly seen in public transportation systems where it is known as “platooni…

> To further the transportation analogy, the buses (scanner threads) in our city avoid clumping by teleporting themselves to a random stop (location in the table) if they get too close to the bus in front of them.

Subway trains do this "to regulate service" iirc is the term used on the London Underground.

Takt time［1］and Drum Buffer Rope［2］both related concepts of regulating flow through a process/system.

［1］ https://en.m.wikipedia.org/wiki/Takt_time

［2］ https://en.m.wikipedia.org/wiki/Theory_of_constraints

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