Tuesday's elections in Virginia include contests for important seats in the House of Delegates. Northern Virginians have much at stake. In recent years the region's bipartisan delegation to Richmond has worked especially effectively to secure financing for major transportation projects -- still the No. 1 issue for northern Virginia. This kind of cooperation, experience and -- with each election -- increased seniority speaks strongly for the reelection of most incumbents.

In District 33 (Loudoun/Fairfax), incumbent Republican Robert T. Andrews is a knowledgeable legislator with a sense of transportation priorities and solid service on the Roads Committee.

In District 34 (Fairfax), Republican Vincent F. Callahan Jr., minority leader since 1982, brings expertise and seniority to the key Appropriations Committee.

In District 35 (Fairfax), Democrat Dorothy S. McDiarmid, senior member of Northern Virginia's House delegation, is in line to become chairman of Appropriations if reelected. Her return to Richmond is of utmost importance to the region.

In District 36 (Fairfax), incumbent Kenneth R. Plum, a Democrat, has served well for six years. His opponent has failed to focus on issues of importance to the region.

In District 37 (Fairfax City/County), Democratic challenger Jeffrey J. Fairfield has waged a lively campaign, emphasizing local control of county roads. Incumbent Republican Stephen E. Gordy has little to show for his two terms.

In District 38 (Fairfax), Democratic challenger Leslie L. Byrne deserves to replace incumbent Republican Gwendalyn F. Cody, who recently was ranked 100th in a rating of the most effective members of the 100-member House.

In District 39 (Fairfax), incumbent Democrat Vivian E. Watts has been exceptionally effective. Her work for a revised highway money formula was critical.

In District 40 (Fairfax), Republican incumbent Robert E. Harris serves on the Appropriations and Roads committees and is an increasingly important member of the delegation.

In District 41 (Fairfax), Republican James H. (Jim) Dillard is the ranking Republican on the Education Committee and a member of the State Water Study Commission.

In District 43 (Fairfax), incumbent Democrat Gladys B. Keating has an understanding of the state's fiscal policies and regional-state relationships.

In District 45 (Alexandria), incumbent Democrat Marian Van Landingham has represented her constituents with vigor and intelligence.

In District 46 (Alexandria), incumbent Democrat Bernard S. Cohen is up against a well financed campaign but has valuable legislative experience.

In District 47 (Arlington/Fairfax), incumbent Democrat James F. Almand is a five-term member with a keen understanding of Metro and highway financing.

In District 48 (Arlington), incumbent Democrat Mary A. Marshall is the senior delegate on a strong Arlington team.

In District 49 (Arlington), incumbent Democrat Warren G. Stambaugh, an effective leader on many legislative fronts, is a key player in Northern Virginia's transportation and financial efforts.

In District 51 (Prince William), Democratic incumbent David G. Brickley has concentrated well on regional transportation issues.