Hours: Open 24 hours, seven days a week.

Atmosphere: Fresh and spirited.

Price range: $5.95 to $15.95 for dinner entrees; special portions for young children can be arranged.

Credit cards: Visa, MasterCard, American Express, Carte Blance, Diner's Club.

Reservations: Available.

Special facilities: Booster seats, wheelchair accessibility, free parking.

Potomac Station has several good things going for it as a pleasant place for a Sunday family dinner.

Located across the street from the Alexandria train yard, it offers train fans a clear view of boxcars, freight cars, coal cars and assorted cabooses.

The restaurant itself has a large parking lot for convenience and a very pleasant decor for comfort. Its soft natural wood tones, standing and hanging plants and stained-glass window from an old-fashioned train cut the restaurant's three dining rooms down to intimate size.

Tables are covered with starched linen cloths and set with brown linen napkins folded into fans. On the walls are delightful drawings of birds.

The menu also is appealing. There are several special dishes (turkey, ham, roast beef) and a big, inviting salad bar. Though there is no children's menu, a hostess assured us that arrangements could be made for children's portions.

The main courses also seemed reasonably priced: roast beef, depending on size, from $6.95 to $10.95; roast turkey or sugar-cured ham, $6.95; and many other meat and seafood dishes for $5.95 to $9.95. All main courses include the salad bar, which was the highlight of our recent Sunday dinner there.

We started with one order of French onion soup gratine'e ($2.95). A super-thick coating of cheese clung to the top of the hot crock of soup and a passable broth bubbled below it. Not bad, but not great either.

From that we passed to the salad bar which, though not of overwhelming size and variety, had some excellent dishes. In particular, the potato salad was delightfully crisp and well-chilled; the beets were as sweet as apples and exceptionally fresh. In fact, everything in the salad line--from the sliced green peppers to the onions, feta cheese chunks, cucumber slices and cherry tomatoes--was well-chilled and crisp.

The salad bar also offered six different dressings and three kinds of bread (pumpernickle, rye and French) plus melba toast.

After enjoying the salad bar we were expecting great things from the kitchen. We were disappointed--in some cases mildly, in others more deeply. The two best dishes we tried were the roast beef, tender and cooked to perfect medium-rare as ordered, and sugar-cured ham, nicely lean and delicately seasoned. Both the $6.95 queen's cut of roast beef and the serving of ham were generous portions.

Less successful was the breast of roast turkey, which covered a mass of overly moist dressing and which in turn was covered by a too-generous ladling of an undistinguished white sauce.

In an order of oven-baked stuffed shrimp ($7.95), the shrimp were tough and the crab meat topping too strong. Our waiter had assured us there were five shrimp to the order, but we found only four.

An order of breaded oysters ($6.95) came off a little better. The breading formed a pleasant coating, but the hot oysters were served on a bed of lettuce, a practice I always find disconcerting.

In addition to the salad bar, entrees come with a choice of vegetable, potato or rice. Those of us who chose the string beans were served soggy canned string beans. The baked potatoes were a better bet.

Overall, we felt the kitchen did well with simpler dishes (the roast beef was excellent) and not so well when the chef attempted elaborate sauces and breadings.

For dessert we tried baklava ($1.65) which was surprisingly tasty, considering that Potomac Station has no Middle Eastern pretensions. Thecheesecake ($1.95) was creamy but otherwise unremarkable.

Dinner for our party of five (three adults, two children) came to $57.23, including tax, a glass of wine and several soft drinks.