It's time to wish a happy 50th birthday to the Calvert Street Bridge, a.k.a. the Duke Ellington Bridge.

A half century ago Saturday -- at 9:30 a.m. on Oct. 12, 1935 -- D.C. Commissioner Melvin C. Hazen lifted wooden barricades at the east end of the bridge across Rock Creek Park and rode the first automobile to make an official crossing of what, to me, is the most commanding of this city's bridges. But only half of the bridge's traffic lanes -- those on the north side -- were opened, and thereby lies a story.

The three-arched span, with its handsome limestone facing, replaced a creaky steel trestle -- the first high-level crossing of Rock Creek -- that had been built in 1891 by a streetcar company primarily to provide access for its electric cars to upper Connecticut Avenue.

As the new Calvert Street Bridge was being built, trolley service had to be maintained. Ingeniously, engineers put the old bridge's piers onto rails and rolled the entire span 80 feet downstream. The track ends were connected with sharp curves. But just before the new bridge was completed -- with facilities included for streetcars -- the company decided to abandon the line in favor of buses.

Commissioner Hazen, the first passenger, was accompanied across the span by Capt. H.C. Whitehurst, the D.C. highway director, of Georgetown elevated freeway fame. It wasn't until the following Dec. 19 that the bridge was fully opened with a full-blown formal ceremony. The lanes on the south side of the bridge were blocked meantime to facilitate the demolition of the old bridge.

At the time of the initial opening, a District government engineer, Clifford R. White, said the Calvert span wouldn't be named for anybody. " . . . . People," he said, "insist on calling a bridge after the street it is on." Years later, that was changed: it's now named for the late Edward K. (Duke) Ellington, a famed Washington-born jazz musician. Numerological Oddity

It was shortly after 3 p.m. Sunday when the Detroit Lions were threatening with the ball on the 3-yard line. And at that point the scoreboard showed 3 Lions points, plus: quarter 3, down 3, yards to go 3, and the time remaining 3:03. Apostrophical Error

Hand-painted banners displayed by fans at pro football games often contain amusing and even charming flubs of grammar or punctuation. But when a banner is professionally done, as with one displayed Sunday at Kennedy Stadium by a Tysons Corner watering hole, someone should see and edit out the goofs.

Metro Scene became apostrophically apoplectic at seeing the banner, omitting an apostrophe where it was needed and adding one where it was erroneous: "Ramblin Redskins Rooter's."