A Parable - Hackdot

Re:A Parable by gojomo on Wednesday January 30, 2013 @01:37PM (#5140956)

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 shunting yards

• able to represent either the original 1:1 carriage:toilet ratio, or the cost-saving 2:1 ratio, or any other ratio that might be desired

• able to represent any desired min-distance/max-distance in carriage-car-lengths to the nearest toilet

• able to be upgraded/serviced independently (including occasional periods of operation outside of usual ratios, as trials or when cars are out-of-service)

Of course the costs of extra couplings (in construction, linear deadspace, and operational overhead), and effects of such unevenly-sized cars on travel characteristics (stability, wear, fuel-economy, etc) might outweigh the explicit flexibility benefits.

But such flexibility is less risky in the abstract and more easily-rewritten world of software where I practice, as opposed to the world of railroad engineering, as practiced (perhaps not coincidentally) by my father's father.

[ Parent | on HN ]

Re:A Parable by 205guy on Wednesday January 30, 2013 @04:30PM (#5141873)

I was at first going to wonder if HN is going to recycle all of CS history, and whether that was a good thing or not. Now I see it may be necessary.

Because your solution needs more CS thinking. Your carriage cars are not reversible when used in any ratio other than 1:1 because they need an arrow inside to point to the nearest toilet-car. Also, in odd-numbered ratios (3:1, 5:1), you would really need a car with arrows going both ways, starting from the middle of the carriage. Or maybe you are selling a programmable LCD arrow signage for the carriages...

There is also one issue with Dijstra's parable: although the new coupling solution doesn't require ever turning carriages around (as long as they are shunted as pairs), it also means carriages cannot be turned around without extra effort. Assuming the turning platforms can only take one carriage, you have a lot of extra work to turn around a pair and get them back together correctly. However, there are track configurations that can turn the paired cars around more easily. In any case, this probably explains why all trains have seats facing both directions: they never need to turn them.

[ Parent | on HN ]

Re:A Parable by myhf on Wednesday January 30, 2013 @06:46PM (#5142536)

Gojomo's design could use windows instead of arrows, so that the toilet car's external signage can be seen from anywhere in the adjacent car's hall. At a 1:1 or 2:1 ratio, a passenger just has to look both directions and go toward the sign they see. At a 3:1 ratio, a passenger who doesn't see a toilet car out of either window could always walk to the door closest to them.

[ Parent | on HN ]

Re:A Parable by neumann_alfred on Wednesday January 30, 2013 @07:12PM (#5142621)

Then the cars to each end of the toilet car would still exist in two types, depending of the direction of the arrows; which means you have 3 different units instead of 1. Reduce conditionals, reduce cache misses! ^^

[ Parent | on HN ]