jjt

Thanks. All good points. I also hadn't considered the leaking that might occur, although that might be fixable with some heavy duty caulking. I was assuming the L-shapes would have grooves+tabs that would make them very easy to line up and assemble. I was also assuming they would be manufactured and transported to keep those cost savings.

I know you weren't questioning the idea of standards or anything; that's just where my mind wandered to.

So, just considering a different standard - your L-shape vs. a box, the thing is that transport is just really cheap comapred to everything else. Sure you save some truck trips, but now you need to lift twice as many big heavy things and put them into place (and then join them, etc.)

Of course, this is just all speculation on my part. For all I know, built-up boxes from L-sections *are* used somewhere.

jt

(I'm not a civil engineer, although I do hold an ancient B.S.C.E.)

I would think that pre-fabricating things like concrete sections is *much* cheaper than assembling them on-site. It's probably pretty hard to line up two massive L-shapes along their length out in the field. While it's true that the pre-fabrication means more waste in transportation, that's a much smaller cost.

Speculating further, every joint/seam/step in a conduit (like any baffle) is going to reduce the amount of water it can carry and present an opportunity for an obstruction to form. The more uniform the section, the smaller it can be to carry a given flow. This is bound to have a big impact on the cost, mainly through making the hole you have to make to put it in smaller, or allowing you to carry more flow given your already existing space constraints.

I remember as a civil engineering student being frustrated by the "waste" inherent in, say, having to pick from a standardized set of I-beams (or whatever) instead of designing something more optimal (and more importantly, fun). Of course with a little more thought, obviously having standards is vastly cheaper system-wide - mills roll standard shapes, their properties go into handbooks, and codes and best practices keep people from getting killed by clever optimizers doing stuff like this:

http://en.wikipedia....alkway_collapse

Much better account than the Wikipedia article, but partially excised, on pp. 221-230 of this excellent book:

http://books.google....q=hyatt&f=false

Now that I'm spending a lot of time looking at how to model the cost and benefits of various system- and subsystem-level design choices in a manufacturing system, I think *that's* the interesting part, not the actual detailed engineering...

jt

Reminds me of my favorite Houston apartment back in the apartment days. It was in that huge old complex that used to be where the Kroger center is now at the corner of Westpark /Buffalo Speedway/Edloe. I had an efficiency there that had an honest to God Murphy bed and a little bitty kitchen with these porcelain covered fixtures all built in including an icebox. Very 40's. It had a back door with a little porch and there were lots of trees and green lawn. It was fantastic and I almost cried when they tore it all down some years later.

I lived there in the early/mid 90s. It was called the Greenway Apts. I used to walk to work in Greenway Plaza down Purdue St. and across the bridge at Edloe. (Purdue is completely gone, but you can see where it was because Kroger kept the trees that lined the street in their parking lot.) Now that I think about it, maybe the "Edloe Apts." were where Kroger is, becuase my apartment was across Buffalo Spdwy., where the retirement home is now. They were nice, basic places. Very 40s, as you say.

jt