Take heed, all of you Eastern Shore weekenders and vacationers who have put up not only with long lines at the Bay Bridge tollbooths but also with the drawbridge at Kent Narrows and the bottlenecks of the Choptank River at Cambridge and formerly at Denton: You'll find another bridge construction project under way for the next two years along the route to and from the beaches.

The Maryland State Highway Administration announced that work will start Tuesday on the redecking and widening of the four-lane bridge that carries U.S. Rtes. 50 and 301 across the Severn River just east of Annapolis. Just in time for the July 4 holiday weekend!

But don't fret, says Highway Administrator Hal Kassoff: Two lanes will be kept open in each direction during peak periods (including the three-day weekend), and one traffic lane in each direction will be kept open at other times.

The bridge deck has deteriorated and is too narrow to accommodate projected traffic, the state agency said. The rebuilt deck will be wide enough eventually to allow three lanes in each direction.

The $18 million project will be done by the Whiting Turner Contracting Co. of Baltimore. Of that amount, $11.2 million will come from the Federal Highway Administration. Metro's Midnight Debut

Hooray, hooray! It's time for a civic celebration! Starting today, the Metro subway will stay open until midnight on Sundays and holidays -- in fact, from now on, every night.

Thus, in Metro Scene's view, after more than 10 years of subway service, Washington finally will move out of the transit bush league. And a great many Washingtonians -- notably those arriving at Union Station or National Airport after 6 p.m. on Sundays -- will escape the grasp of cabdrivers. Personal experience, while anecdotal, is instructive: I've never, on many such arrivals, boarded a cab when the driver was not surly and resistant because my trip was not long and costly, though too far to walk.

The problem has been especially awful on Sunday and Monday nights at the end of three-day holiday weekends and worst over the four-day Thanksgiving period. This column set up a periodic drumbeat of agitation, and some well-placed people at the transit authority say Metro Scene influenced the decision to extend the hours despite a tight budget. True or not, we rejoice. Chip in for Children

Twice a year my columning colleague Bob Levey spearheads fund-raising campaigns for two of Washington's worthiest enterprises, Children's Hospital and the summertime Send a Kid to Camp campaign, which this newspaper adopted after its original sponsor, The Washington Star, folded nearly five years ago.

Bob Levey's Washington appears in weekday but not Sunday editions of the Post, but his plea for the camp fund is one that deserves contributions from Sunday-only readers, too. As of Thursday, $85,852 had been raised toward a goal of $200,000. Join me, please, in sending a check or money order made out to "Send a Kid to Camp," care of Bob Levey, The Washington Post, Washington, D.C. 20071.