The long-awaited, controversial rebuilding of the Whitehurst Freeway is now scheduled to begin Dec. 10, creating a new traffic pattern that may be frustrating for thousands of drivers throughout the region.

Starting with the morning rush hour that day, the four-lane elevated roadway along the Georgetown waterfront will be reduced to two lanes, with traffic moving in only one direction.

About 50,000 vehicles use the 41-year-old bypass of Georgetown each day, and many of them will now scatter to other roads, such as M Street in Georgetown, the George Washington Parkway in Virginia, the Theodore Roosevelt Bridge and Rock Creek Parkway.

Perhaps even more disruptive for many commuters, the two ramps connecting the freeway to Key Bridge will be closed.

Drivers heading east into the District will be able to use the freeway in the morning and on weekends, but drivers going west out of the city will be restricted to using the Whitehurst between 2:30 p.m. and 9 p.m. on weekdays.

The reduction of lanes is necessary, District public works officials said, because crews will first demolish and rebuild the south side of the bridge deck, which includes two lanes. Officials considered it unsafe to allow two-way traffic to move in the two narrow remaining lanes.

The project will take 2 1/2 years to complete. The one-way pattern probably will be in effect for at least 15 months, officials said.

For the next seven months, the ramp leading from the Key Bridge to the Whitehurst, used by about 10,000 vehicles a day, will be closed.

The westbound ramp, now used by about 10,000 vehicles a day to enter the Key Bridge, also will be closed.

Until the 15-month period is over, officials are asking outbound drivers to use the Roosevelt Bridge, which has a new fourth outbound lane to handle some of the spillover from the Whitehurst.

They also prefer that inbound Maryland drivers using the Capital Beltway cross the American Legion Bridge and take the George Washington Parkway in Virginia to enter the city, especially in the afternoon and evening, when the Whitehurst is restricted to outbound traffic.

When the work is completed, the Whitehurst, which is named after a former District highway official, still will have four lanes, but will be eight feet wider to allow for shoulders on both sides. Its bridge structure will be repainted in two tones to give it a less-gloomy appearance. The project will cost $35 million to $40 million, most of which is federal money.

Several people and organizations opposed the project, preferring to demolish the freeway and start over with a grand boulevard along the waterfront. City officials challenged the safety and cost of that plan.