It's 50 or 60 years ago, it looks like--late fall, call it early winter at the Red Mountain Town Depot in Colorado. On the hill behind the depot there is early snow on the fir trees and the walls of rock. There's a stream that froze and melted and refroze--you can see some chunks caught in the new ice. And of course there are the railroad tracks, a little rusty except where the rails move by the switches, and a beat-up gondola car with the planking oil-stained and busted.

It's an odd between-season scene that rouses all the lonesome-whistle, hard-edge forlornness of life in a lumber camp, detailed down to a few tiny icicles hanging under the depot eaves--not the big skullpunchers that will lurk there later, but still big enough that the builder of this scene, one Robert D. Ross, leaves a warning next to it. It says that if anybody pulls the roof off the depot to look at the tiny furniture inside, the fingernail-size documents on a matchbox-size desk, they'd better not set it down or the icicles will break.

"Geo-socio-political sculpture," says Samuel Powell, a piano tuner from Gaithersburg. Like thousands of other people convening this week at the Sheraton Washington hotel, Powell is a builder of model railroads.

Near him in the convention's contest room, judges are studying the Red Mountain depot, tables full of engines and railroad cars, a model of Billy Carter's gas station, a piece of a steel mill, a coaling station with stains trailing down the sides from rusty nailheads, a whole California logging camp (complete with a Chinese hanging out the wash, and a lumberjack studying a newspaper in the outhouse), a weatherbeaten store with rusting tin roof, and a trolley maintenance car that duplicates one still working on the Yakima Valley Traction Line in Yakima, Washington. It's all patinaed as funky and scarred as the life it emulates.

With his theories about model railroads being geo-socio-political sculptures, Sam Powell may be a little out of the convention's mainstream, but he's got a point that's proved by the contest entries--the glory of them isn't just nuts and bolts detailing, it's the feelings they evoke.

"The great controversy in model railroading is always whether form and function are balanced," says Powell, who has a 440-square-foot S-gauge layout that hundreds of conventioneers have been busing out to Gaithersburg to study, this week.

"Form is how pretty it is, and function is how much like a train it looks. In the last 15 years, techniques have become pretty stylized and predictable, and the function end has peaked out. There's an opening for the form to start getting more important."

This is not kid stuff.

Says John Glaab, chairman of the conference: "The public has never taken this seriously--they think there has to be a Christmas tree in the middle of the layout."

There are 28,000 members of the National Model Railroad Association, and the magazine Model Railroader has a paid monthly circulation of 188,000. According to convention literature, the hobby moved away from toy trains and got serious when model railroad builders began to standardize equipment in the mid-1930s. Nowadays, HO scale--1/87th of actual size--is the favorite. The old O scale (1/48th), familiar to anyone who ever had the traditional Lionel or American Flyer trains, is still popular, and a mammoth layout at the convention, with one 81-car freight train, is done in N scale (1/160th). There's also itty-bitty Z scale, with locomotives the size of your thumb. For people who don't mind having to build most of their own equipment, there's S scale, between HO and O, which Powell works in.

It can get expensive and time-consuming, with a fine brass engine costing more than $1,000, and a diorama such as Red Mountain taking more than 1,000 hours of work. (The average year for an American worker, at 40 hours a week, is 2,000 hours.)

"It costs a bundle and a bundle and a bundle," says Roxie G. Odenwalder of Memphis. "All those details. You got to have all those little people alongside the tracks, and they can cost $2 apiece. You pick 'em up with tweezers then you lose 'em and have to look for 'em for two weeks."

Model railroading has meant enough to enough people in the last 50 years that it has its great men, such as John Allen, Frank Titman, Allen McClelland, Frank Ellison and others who are famous here at the convention.

"John Allen practically invented weathering," says Powell, describing the origins of the trend away from toys and toward the recreation of reality. "People got very upset. One of his first models had pigeon dung on the roofs--it created a real stir. Now you can buy that model in a kit. Allen also got model trains off the table top, got away from having all-horizontal layouts. Frank Ellison talked about it as a stage--the trains are actors, the buildings are props. What I'm doing right now is trying to understand what those guys were doing."

Powell holds clinics that discuss things such as layouts evoking "reemergence of residual emotions" and the comparative "rhythms" of having the trains move right-to-left (strong) or left-to-right (weak).

With this kind of thinking going around, the convention is full of trains and layouts that evoke not just the mechanics but the actual sensation of the reality under consideration--that odd, sweet, grimy nostalgia for the workingman greatness of America, hearing that whistle blow, man and industry stitching the country together with tracks and trestles, a whole idea of life that our painters and sculptors stopped portraying when esthetics of social realism died during World War II.

Still, there isn't apt to be such a thing as abstract-expressionist model railroading. The feelings and ideas are too rooted in the ideas.

In the Red Mountain layout the depot roof is smaller than a pair of postcards, and is made of 3,300 separate shingles, each cut from the kind of cedar that is sometimes used to wrap cigars. The rock foundation is made of actual crushed rock from Colorado. The artist writes: "My goal was to exactly duplicate the Red Mountain town depot."

The fir trees, leafed with dried asparagus fern, are especially good, trees being one of the hardest tests of a modeler's art, as shown by the old saying:

"Even on a model railroad, only God can make a tree."

On another table, a Heisler No. 2 narrow-gauge locomotive is a replica down to the oil spill on the "bunker" car, an effect achieved by a final brushing of dirty liquid over five other brands of paint and fixative, all used to achieve weathering, and not to be confused with all the paints and finishes that go into making the locomotive not just flat black but a black that hits the eye the way the paint on the full-size locomotive would.

One railroad station has windows with simulated dirt, and individual stained-glass panes small enough to go through the eye of a medium-size needle.

One of the motivations for all this work is to build a world over which you have total control. But if Powell is right, there has to be more.

Is it ever possible, after putting in all that work and knowing where the flaws are, that a modeler can walk past his work and see it out of the corner of his eye, and for just a second, have the feeling that it's even better than perfect--that it's real?

Says Powell: "I had a guy looking at my layout, and when a train came out of the tunnel, well, you should have seen his face, the way he felt, the total delight. You don't see that on people's faces that often."

Says Jay Rogers, a judge: "That's the whole idea."