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Think Airports Are Chaotic? You Are Right.

michael posted about 11 years ago | from the entropy-increases dept.

Science 24

jonfromspace writes "Nature is running a brief, but interesting article on Chaos Theory, (as opposed to KAOS) and how it relates to that damn airport shutle service. I knew there was no way to predict arrival times with any degree of certainty. >Also worth a read is this paper on applying Chaos Theory to fisheries management."

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Not to be a pedant about it, (3, Interesting)

The Cydonian (603441) | about 11 years ago | (#7100379)

but the Nature article talks about airport bus frequencies, not airports per se.

The distinction is important though; when you talk of 'chaotic airports', you're talking of the entire system as a whole:- luggage screening, plane scheduling, passenger movements etc. Dr Nagatani's paper talks about none of these; it merely suggests that the reason shuttle buses (and elevators) appear to come together, or none at all, is chaos.

I can understand where Dr Nagatani is coming from on explaining bus (and elevator) frequencies, but am intrigued by why it is a "problem" (as in user-level problem, not physics problem, if you get what I mean) in the first place. Okay, so the bus comes at 09:23 and not 09:15... big deal. It is merely a matter of managing passenger perceptions.

More to the point, can anyone explain why this would be inefficient for the system as a whole?

Re:Not to be a pedant about it, (4, Informative)

Dannon (142147) | about 11 years ago | (#7100668)

More to the point, can anyone explain why this would be inefficient for the system as a whole?

Managing bus services isn't my line of work, but I can give it a shot.

For starters, I'm guessing the "bunching problem" would lead to inefficiencies, for one thing, in passenger loading: The 9:15 bus and the 9:20 bus are both bound along the same route. The first bus is early, the second bus is late... meaning that the first bus ends up overcrowded (grouchy customers), and the second bus departs from the stop under capacity (same amount of fuel spent whether carrying one passenger or twenty).

There's also the problem of limited resources. Say you've got more shuttle busses than shuttle bus loading spaces at a certain airport. I look at the international airport in my town, and I see shuttles for several park-and-ride services, countless conference centers, every high-class hotel in several hours' drive, not to mention the usual collection of Grayhound, metro transit authority, touring companies, and so on. The optimal situation would have an empty space ready for each bus as it arrives, so the passengers wouldn't have to wait to disembark. As things get more chaotic, though, they get less optimal. That's all there is to it.

Talking about changing passenger perceptions, though, reminded me.... My page-a-day calendar at work had a bit about how the London rail service managed to fix a problem with chronically late trains without spending any money at all. They simply redefined "on time" to include any train up to an hour late. Problem solved, right?

Old news? (1)

BrokenHalo (565198) | about 11 years ago | (#7101038)

Perhaps this could be extended to other services; Douglas Adams once referred to the Greek ferry timetables as "the greatest work of fiction known to man", and others have drawn the same parallel to British Rail timetables...

Re:Old news? (1)

The Cydonian (603441) | about 11 years ago | (#7101211)

That was in Dirk Gently's Holistic Detective Agency wasn't it? :-)

Re:Old news? (1)

BrokenHalo (565198) | about 11 years ago | (#7103108)

Indeed it was... at least if I remember the quote correctly.

Re:Old news? (1)

ForestGrump (644805) | about 11 years ago | (#7105474)

Its also a matter of management and the drivers.
If the manangement is lose, and the drivers don't care. Then the drivers will skip stops or drive faster, arriving early, leaving early- so that they get their round done faster and go home sooner.

Management needs to understand where the people will be and at what times. Then they need to make more busses available at that time. Stick a GPS on a few random busses, and the drivers will fall in line. Maybe even mount video cameras at major bus stops to monitor number of people.

Lastly, I have to differ from your post.
If the mass transist, in the past has ran on time, Mussolini made the trains run on time, and thus he won political control of Italy.

Re:Not to be a pedant about it, (1)

thogard (43403) | about 11 years ago | (#7120027)

Getting around in an airport today can waste huge amoutns of time. For example I can get to the local airport 20 minutes before departure and still get on the plane if a large number of other factors are right such as its not the morning or evening rush and there normal gate is being used so I don't have to count on a shuttle and no group is on strike. Other times I may need to be there two hours before hand and in some airports 4 hours is pushing it.

Of course the solution to that nonsense would be put the final check in time on the ticket. There are only two people on most planes that care what time the plane leaves and they get the front seats. Most everyone else needs to know what time they need to be in the check in line.

Sure is better now (1, Funny)

Anonymous Coward | about 11 years ago | (#7100384)

I remember during the late 1970s you could sometimes find OJ Simpson flying through the airport like Superman.

In other news... (2, Insightful)

Anonymous Coward | about 11 years ago | (#7100428)

Think slashdot moderations are chaotic? You are right!

Trivia question for technically inclined (-1, Offtopic)

Anonymous Coward | about 11 years ago | (#7100524)

Trivia question for those who are curious and know their stuff.

What's the most secure protocol for purely Microsoft networking environment? The question assumes presense of Windows Server on one end and unspecified Windows client box on another end.

Correct result will be posted in three hours. Please post your answers.

Bunching buses (5, Insightful)

driptray (187357) | about 11 years ago | (#7101159)

Regular bus commuters might be familar with the phenomenon where buses tend to come in groups - often in threes. For example, instead of 1 bus every 10 minutes you get 3 every 30 minutes.

Why? My theory is that as the system becomes crowded, a bus will be delayed by having to pick up and drop off extra passengers. As it gets slower, two things happen:

  1. People have to wait longer at the bus stops. This causes the first bus to have to deal with a greater number of passengers, and makes the bus slow down even more.

  2. The bus behind it starts to catch up. This occurs partly due to the slower speed of the first bus, but is amplified by the fact that as the second bus gets closer, there will be less passengers waiting at the stops, thus allowing the second bus to travel even faster.

The solution would be for the first bus to deliberately miss stops wherever possible so as to keep some distance between it and the next bus, and to even up the passenger load.

Re:Bunching buses (2, Funny)

panurge (573432) | about 11 years ago | (#7101531)

In fact there is supposed to be a paper about this though I have been unable to locate it.

One of the surprising conclusions is that on some routes the best time to arrive is just as a bus is leaving. There are a number of reasons for this. One is that the departing bus has reduced the queue length at the bus stop so you are more likely to get on the next bus. Another is that if the buses tend to group, in groups >= 3, if a bus is leaving the probability that it is not the last bus in the group is >0.5. If you arrive with no buses in sight, chances are you are in an inter-group period.

My favorite comment on the whole bus thing, however, came from a retired admiral who wrote a letter to the London Times: "Since the convoy system was introduced, not a single bus has been sunk by enemy action."

Re:Bunching buses (2, Interesting)

wind (94988) | about 11 years ago | (#7101771)

At least where I live (Brighton, UK) this appears to be exactly what the bus drivers do at peak times, at least up in the hinterlands of the residential areas. I can't tell you how many times I've waited an extra 10 minutes for the bus, only to have it speed past me with bus driver sternly shaking his head. Then the next bus comes a minute later.

Thing is, it doesn't appear to help. Usually afterwards the buses still end up next to each other. Understanding that it's due to being a chaotic system probably won't help being frustrating, but at least it's something, I guess.

Honestly, I don't drive anymore and don't really want to start again, but it's at those moments where I gain a visceral understanding of why cars are so popular. Kind of an anti-Zen moment, I guess.

Re:Bunching buses (1, Interesting)

Anonymous Coward | about 11 years ago | (#7102144)

I live in Minneapolis, MN and the busses here regulate this actually. What they do is, if they are too far ahead of schedule, they have a computer on board that will tell the drivers to pull over and wait for some amount of time (provided they're in a place they can do this). The busses all have some type of GPS on board too because it will alert the drivers if they are not on a specified route. If they are behind schedule I dont know what they do in thta instance. I've never had a bus more that 5min late but I've only become semi-regular ride for about 3yrs.

Re:Bunching buses (2, Interesting)

p3d0 (42270) | about 11 years ago | (#7103499)

In Toronto, I have seen TTC busses leapfrog each other, presumably for exactly this reason.

Re:Bunching buses (1)

harrkev (623093) | about 11 years ago | (#7104593)

I have this book from Amazon [amazon.com] . It is actually quite a good book which even covers this topic. This particular problem is even in the title!

If you like books on recreational mathematics without being too burdened down in homework, this one is worth a read.

gay (-1, Troll)

FedToTheDogs (696706) | about 11 years ago | (#7102164)

gay "kaos" Fuck you vgbastard, shit, monkeys could some up with more interesting commentary, let's brinh a porn star on and add "Like ive stuck my cock in a woman to it"

Life, The Universe, and Everything. (1)

Bri3D (584578) | about 11 years ago | (#7109278)

This kind of reminds me of the book, where the starship Bistromath operated off of the times and operations in an Italian restaurant.

more then chaos (0)

Anonymous Coward | about 11 years ago | (#7112060)

yeah and talk about that old lady that can
hardly carry her bag with a does niffty clothes
and shoes she's never going to all wear on
her trip anyway (don't you jst love travellers/
tourist who can't carry there baggage because
it's too heavy?).
or the drunk guy spilling his beer on fellow
passengers willst bording the bus.
or the other woman who brought her little dog
along and after bording, uuh, has to suddenly
go take a pee.
or that other guy who just so happend to have
lost his wallet.
or another guy who doesn't have small change but
a 50 dollar/bucks bill.
oh, and uuh, the bus had a flat tire. ...
please add your example [here]
so much to chaos. the humane sytem is promoting uniformaty, sorry.

Re:more then chaos (1)

jpr1nd (678149) | about 11 years ago | (#7116792)

your "writing" makes my head hurt.

Is this a surprise? (1)

henrygb (668225) | about 11 years ago | (#7112091)

The abstract is here [aip.org] with links to the full article for subscribers.

I don't see anything unexpected in the report. In particular the statement "When the loading parameter is larger than a threshold value, each bus carries a full load of passengers throughout its trip" means "if more passengers want to use the service than the buses can carry, then the buses will be full and the queues of passengers will get longer over time". This is a standard result of queuing theory as well as being common sense.

obligatory D&D quote... (1)

Creepy (93888) | about 11 years ago | (#7113251)

Ok, I have to say it...

My airport has always been a Chaotic Evil Thief.

my apologies to D&D

If you let chaos rule.. (0)

annisette (682090) | about 11 years ago | (#7120064)

it will.
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