DON'T LOOK NOW, but do so in about two years and you may discover that Washington has a real, live, grand and glorious train terminal in its midst. There's a train station here now, of course, but the terminal part of it is not in the midst of anything: it's barely in the same cab zone as the front door of the station. Only yesterday, in fact, did the first party of pioneers to set foot on the font entrance of Union Station nine years ago finally make it to trainside. The reason is that, as taxpayers from coast to coast learned to their horror over the past decade, for the bicentennial, Union Station became a mammoth federal demonstration project -- demonstrating how to memorialize waste, desecration and absurd design in a monumentally expensive, fast-deteriorating and inefficient setting.

So meticulously ruined was the station that it has taken ever since just to abate the abuse, neglect and federal misdirection before trying to put the place back together again. That is why we were impressed two years ago, when, in her first month in office, Transportation Secretary Elizabeth Hanford Dole went up to Union Station and announced an agreement, with cash at the ready, to bring back a semblance of the train terminal we used to know and love. And this week, the architectural plans are actually being circulated for public scrutiny.

The designers envision a mix of the old magnificence and contemporary commercial uses, with shops, restaurants, movie theaters and -- can you stand it? -- trains you can really get to without backpacking native guides and a three-day supply of water. The challenge will be to make sure that "contemporary" doesn't turn into California-kitsch-in- the-colonnades, that the grandeur of the exterior isn't violated inside.

So far, at least, Mrs. Dole and the federally backed nonprofit redevelopment corporation set up to do the work have shown keen interest, political savvy and a sense of Union Station's historical and local significance in moving to stop what has been unstoppable federal waste (the lease never quits) and to rescue a landmark.

It will help considerably, of course, to keep on having trains there -- which is not exactly a sure thing if federal subsidies are abruptly yanked out from under Amtrak, as the Reagan administration is proposing. Still, the Union Station developers believe the venture would remain sound. That is something it hasn't been in years.