The Wiehle-Reston East Station on the Silver Line is seen in this file photo. (Matt McClain/The Washington Post)

Metro officials said Monday that the Silver Line has exceeded expectations during its first year of service by drawing new riders, spurring development in Tysons Corner and Reston and helping reduce traffic congestion.

But officials with the rail service also said the new line had fallen short of meeting its ridership projections. An average of nearly 17,100 riders board trains during weekdays at the five new stations in Northern Virginia. Those numbers put the Silver Line at about 70 percent of its projected ridership for its first full year of service. Planners had anticipated 25,000 riders boarding daily.

Still that didn’t stop Metro officials from throwing the Silver Line a birthday party, complete with cake, to celebrate its first year of service.

“It’s taken 53 years to get to this point. But we got there,” said Rep. Gerald E. Connolly (D-Va.), who was among those who joined Metro officials and business leaders from across the region for the celebration in Tysons. “It was an up and down thing. It had more near deaths than any project I have been involved in in my life. But we stuck with it, and it really is making a difference.”

Metro officials said the lower-than-projected ridership numbers do not reflect the impact of the Silver Line, the first new line added to the Metrorail system in more than 20 years. And they pointed out that booming construction of residential, office and commercial spaces was driven in part by the new Metro stations: Wiehle-Reston, Spring Hill, Greensboro, Tysons Corner and McLean.

“Everything else has come along. The trains are running. The development is here. . . . The employees will come,” said Jack Requa, Metro’s interim general manager, noting that the projections were developed before the downturn in the economy. “It will exceed the expectations in the long run.”

To celebrate, Metro officials were joined by business leaders and Northern Virginia elected officials to sing “Happy Birthday” to the Silver Line, cut a seven-layer birthday cake featuring a 7000 series train and paint Metro as the catalyst for change in Tysons. Since Metrorail’s arrival, new buildings have emerged, sidewalks have been built and the infrastructure for a walkable community is starting to take shape in an area known for its traffic and six- to eight-lane roads.

A traffic study by Wells and Associates suggests that traffic in Tysons has decreased in the past year, with some intersections experiencing up to 15 percent fewer cars during Metro’s peak travel times.

The Wiehle-Reston East station, the current end of the Silver Line, surpassed its first-year ridership projections with nearly 9,200 boardings — or 18,400 weekday entries and exits — last month.

The Tysons Corner station is one of the system’s busiest on Saturdays, an indication that people are taking the train to get to the Tysons commercial centers.

The bulk of the riders are people who are using the Silver Line instead of the Orange Line. But, Metro said, at least 6,000 are new riders.

Latoya Thompson, 30, is one of them. Every afternoon she travels from her home in Southeast Washington to work at the Tysons Galleria. She said she never came to the Tysons area before the Silver Line, but once it opened, she looked for job opportunities there.

“When I got a job here, it was good that it was actually next to the station,” said Thompson, who works an afternoon shift as a security guard at the mall. “Two years ago, I wouldn’t have worked here.”

Although more than half of Silver Line riders are taking the train into Washington, Metro data suggests that many passengers are getting off at the new stations in Reston and Tysons, an indication of a reverse-commute trend that officials said would only expand when the second phase of the Silver Line is completed.

That phase of the $5.76 billion rail project is 13 months behind schedule. It will add six stops, including one at Dulles International Airport, and will extend Metro service to Loudoun County.

Project officials announced earlier this month that new problems, including cracks in the girders that will support the tracks at Dulles Airport, forced crews to halt work. On Monday, officials said that the completion of the 23-mile project is critical to the viability of the Dulles Airport development corridor and the airport, which has struggled in recent years with declining passenger numbers.

Now that the stations are there, business and government officials say, the next step is to build infrastructure around them to make the area more welcoming to pedestrians and cyclists. That means adding sidewalks, crosswalks and bicycle lanes. Recently, the area added a new car share system.

“That’s another tool for enabling people to come to work without their car,” said Michael Caplin with the Tysons Partnership, a nonprofit association that represents businesses. “We are trying to reduce the barriers that will enable people to keep their cars at home.”