BUSINESSES LINING the construction along Metro's long-delayed Green Line subway route are struggling -- but fortunately the city government is sympathetic. Only mud and boards, chain-link fences and concrete barriers line much of that route, with construction along 7th, 13th and 14th streets unavoidably blocking off roads, sidewalks, parking spaces and -- needless to say -- customers.

Edward Archie's 7th Street NW Tuxedo Valet shop was typical. Mr. Archie didn't think he could hold on long enough to welcome the customers he expected when the Green Line would open. But a little-known city government effort called "MET" gave him more than just hope. Through MET, Mr. Archie received a $20,000 loan. He won't have to start payments until the subway is open, and his business has picked up again.

MET is offered through the city's Office of Business and Economic Development. It has made $120,500 in 3 percent interest-rate loans and $87,625 in grants to six businesses. More have applied for funds. Only struggling businesses along the Green Line can get this federal money, and it can be used only for utilities and other expenses.

Mr. Archie and others like him will still have a long way to go, though. The Green Line isn't scheduled to open until late 1990. Even then, there are no guarantees of sudden prosperity. One has only to walk from the King Street subway station in Alexandria toward Old Town to see the empty buildings of small businesses that were bought out. Many shops along the Green Line probably should be sold. The District government says it runs MET to keep them open long enough to give them the choice to stay or sell.

Several years ago, before the devastation of the 1960s, the area in Northwest was alive with commerce. Mr. Archie hopes it will be that way again when the subway opens -- but that's not likely. The MET money will run out long before most of the businesses have been helped. Some of those businesses will have to be sold. Still, it's better to help them survive until the line opens, and that's why MET is such an important operation.