Three road and bridge construction projects, one already underway and two expected to begin this spring and fall, will cause some traffic delays for area motorists.

The largest of the three projects is the $13.1 million reconstruction of three small bridges leading to the 14th Street Bridge. That project is to begin in about two months.

The approach bridges, on the District side of the 14th Street Bridge, carry 14th Street traffic over Maine Avenue, a channel to the Tidal Basin and Ohio Drive south of the Jefferson Memorial. All are badly deteriorated, constantly filled with potholes and will be replaced by wider bridges with shoulders and barriers, according to the D.C. Department of Transportation.

Another project scheduled to begin this year is reconstruction of Chain Bridge near the District-Montgomery County line. Work on Chain Bridge is to start in September when the National Park Service is expected to finish resurfacing five bridges along the George Washington Memorial Parkway in Virginia.

The badly deteriorated Chain Bridge will be widened, an 8-foot wide bicycle-pedestrain lane will be added and a new stairway and bike ramp to the C&O Canal towpath will be constructed. The Chain Bridge project was approved by the National Capital Planning Commission last week and will be opened to bids shortly.

The third project -- on Canal Road between Chain Bridge and Georgetown -- began last month.The resurfacing project is expected to cost $1.5 million.

Following are the traffic changes that will be in effect during the three construction projects:

14th Street Bridge Project: During the two-year project, all traffic heading toward Virginia, except during evening rush hours, will be diverted to the 9th Street expressway, the Southwest Freeway and 15th Street as it passes near the Tidal Basin and the Jefferson Memorial. During the evening rush, weekdays from 3:30 p.m. to 6:30 p.m., Virginia-bound cars will be allowed to use 14th Street in the construction area.

Washington-bound traffic will be permitted to use 14th Street, except during evening rush hour, when it will be diverted to the Southwest Freeway.

The changes are expected to begin in May.

Chain Bridge Project: During the 18th-month project, two of the three traffic lanes on Chain Bridge will be closed, and traffic on the remaining lane will be reversed during weekdays. Only Washington-bound traffic will be permitted in the mornings and only Virginia-bound traffic will be permitted during evening rush hour and at night.

On weekends, the Chain Bridge will be open only to Washington-bound traffic.

Canal Road Project: Since the work is being done between 9:30 a.m. and 3:30 p.m., rush hour traffic will not be affected. During non-rush hours, only Washington-bound traffic will be permitted on Canal Road between Arizona Avenue and Georgetown. Between Arizona Avenue and Chain Bridge, Canal Road will remain open to two-way traffic at all times.