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A Parable

cs.virginia.edu

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Re: A Parable

#51

Post by guard-of-terra »

USSR electric trains have a similar design feature: it consists of two kinds of cars, one has pantograph and the other has some other equipment which makes it hum when it stands still on the station.

And they're always interleaved like this: chphphphphc (c - car with a cabin, p - car with pantograph, h - hummy car) I wonder if it ever caused logistical problems when assembling trains from cars. Probably not since they are visually different and not sensitive to flipping.

P. S. And toilets? You only had two - one in each cabin cars.

Re: A Parable

#52

Post by digitalengineer »

onemorepassword wrote: post #15

Ironically, this kind of "cost-savings" is exactly what the Netherlands railways have been doing over the years (only by closing half the existing toilets). However, they ended up with the ultimate solution: ordering new trains without any toilets . No joke, they even came up with the brilliant idea of handing out plastic bags for "emergencies"...

Correct! Here's an image of the so called 'Travel John' http://bit.ly/Vs9W2G (Google Images). There is still a bit of a problem for the ladies or 'number 2'.

Re: A Parable

#53

Post by mistercow »

dbaupp wrote: post #29
mistercow wrote: post #27

Earlier quoted context omitted.

>but I would have been happier if the root cause was fixed. But it was fixed. It just took a clever enough incremental improvement to move back to square one.

It's not quite square one: there's half as many toilets on the train, which probably does save money.

Except that you now effectively have cars that are twice as long and articulated in the middle. If one half of the double-car is damaged, both have to be taken in for repair, and both have to be transported and handled as a unit.

Presumably, the previous single-car size had already been optimized for pre-toilet criteria, and changing that by a factor of two probably massively screws with at least some of those criteria. It's hard to believe that the costs savings for having half as many toilets significantly outweigh those other factors.

Re: A Parable

#54

Post by Tichy »

bernardom wrote: post #32
Tichy wrote: post #11

Earlier quoted context omitted.

Me too. It's obvious that the two permanently coupled cars are really just one big car with a toilet, and it's obvious from the start that they should just have put a toilet in every car. But that's too easy to be the point, I suppose? Maybe it is a parable against yet another workaround?

Having two permanently coupled cars is obvious. It is NOT obvious that they should have put a toilet in every car. The solution works quite well and you save a potentially large amount of money.

But then they could have just build bigger cars to begin with, which would have been even more efficient?

Re: A Parable

#55

Post by Yhippa »

First of all, Wahoowa.

Second of all this does delight me. I feel like I deal with this on a daily basis with scope creep in my projects.

On one end of the spectrum you can have an over-engineered project and take forever to get to a requirements decision only to keep kicking down a bad requirement down the chain due to the investment involved.

On the other end you have little to no requirements and you keep discovering new requirements all the time. Scope creep can get ugly here.

Re: A Parable

#56

Post by toddsifleet »

Tichy wrote: post #54
bernardom wrote: post #32

Earlier quoted context omitted.

Having two permanently coupled cars is obvious. It is NOT obvious that they should have put a toilet in every car. The solution works quite well and you save a potentially large amount of money.

But then they could have just build bigger cars to begin with, which would have been even more efficient?

That would affect turning radius, and what tracks the train could run on.

Unless of course you built them like the large buses with a swivel in the middle, but then you get into non-standard stuff.

Re: A Parable

#57

Post by Dove »

I have told the above story to different audiences. Programmers, as a rule, are delighted by it, and managers, invariably, get more and more annoyed as the story progresses; true mathematicians, however, fail to see the point.

If I may venture an explanation for that, it is that the different groups identify with different people in the story.

Managers identify with the cost-cutter. It is a story about the futility and difficulty of doing their jobs, particularly in the midst of unpredictable technical problems. Above all, it is about engineers' failure to just get things right the first time. It is a tragedy.

Engineers identify with the shunting-yard folks and especially with the final brilliant solution. It is a heroic story, a story about succeeding against unreasonable demands, dominating an unkind and unfair world with a simple idea.

Mathematicians identify with no one in the story. It is a mundane story about an uninteresting and unnecessary practical problem, self-inflicted and then solved in an elementary way. The problem is not general, the solution is not interesting, and no one in the story is very smart.

Re: A Parable

#59

Post by [deleted] »

gojomo wrote: post #48

It may be a symptom of my own possibly-pathological preference for reusable modular design, but I'd want to make tiny toilet-only cars. Borrowing anonymouz's diagram style: +---------------+ +-+ +---------------+ | | |T| | | +---------------+.+-+.+---------------+ O O O O O O Then all carriage-cars and toilet-cars are… • reversible • interchangeable with others of their type • easily externally identifiable at shunti…

[deleted]

Re: A Parable

#60

Post by Semaphor »

run4yourlives wrote: post #38
JumpCrisscross wrote: post #31

I'm an economist and saw a story about innovation. An arbitrage was identified and, after some searching, a mechanism found to exploit it. The process was messy, but resulted in a system which increased profitability (or lowered ticket prices or freed up capital to make the chairs comfier) by more efficiently allocating limited resources (note that none of the complaints were about lines outside the toilet) through t…

I wonder how much profit was left on the table though because of this "innovation". :-)

Theoretical economist. The trains run forever.
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