Liz Willis pedals across the Woodrow Wilson Bridge as she heads home from work in Alexandria on May 3. The Woodrow Willson Bridge trail has become an important commuting pathway between Prince George's County and Alexandria. (Bonnie Jo Mount/The Washington Post)

Liz Willis’s commute changed after the Woodrow Wilson Bridge trail opened almost four years ago.

First, she explored it on foot and by bike to experience the scenic views. Before long, she had started biking, one way, over the bridge to her job at Fort Belvoir. Now, she’s commuting back and forth, nearly 40 miles in all, on workdays.

“It has been an ad­ven­ture,” Willis said. “I go very slow, I enjoy the ride and I meet people all along the way.”

The paved pathway that extends across the Potomac River between Oxon Hill and Alexandria has given Willis and other residents of that part of Prince George’s County a safe, comfortable link to a network of Northern Virginia cycling trails.

The bridge trail connects the growing National Harbor development and the cultural attractions of Old Town Alexandria, fulfilling the vision of planners who incorporated the 12-foot-wide trail into the $2.5 billion project to replace the old Wilson Bridge.

A map of the Woodrow Wilson Bridge trail

The new span was a massive, regional undertaking, intended to speed vehicle travel on the Capital Beltway, and the path planned for pedestrians and cyclists was a tiny piece of the project when it was sketched out more than a decade ago .

At the time, the boom in bike commuting was years away. But as thousands of people across the region prepare for Bike to Work Day on Friday, the planners are looking very smart.

Prince George’s officials said use of the 3.5-mile Wilson Bridge trail has increased dramatically since it opened in 2009. In March, the Maryland-National Capital Park and Planning Commission recorded 26,827 crossings, up from 13,998 in March 2012. (In both cases, a trip back and forth was counted as two crossings.)

Many crossings are made by guests of National Harbor who decide to visit Old Town Alexandria, too. Others are made by residents who are biking, jogging or walking. And then there are commuters, including Willis, who have found a convenient route from Prince George’s to Northern Virginia and downtown Washington.

“The more the region interconnects these various bike trails and bike lanes, it just makes biking a more attractive option, not only for commuting but also for other activities,” said Robert Griffiths, a transportation specialist at the Metropolitan Washington Council of Governments .

Biking as a way to commute has surged in the Washington area, particularly in the District, which is considered one of the country’s leading cities for bike commuting.

The installation of bike lanes and the availability of rental bicycles through Capital Bikeshare have spurred the number of District bike commuters, who have more than doubled in the past five years, according to Census Bureau figures.

The trend is also picking up in some of the suburbs, whose governments are promoting cycling as a mode of transportation. Last month, Montgomery County announced a contract with Capital Bikeshare to establish bike stations to the county. The fast-growing bicycle-sharing network, launched in the District in September 2010, has reached the 4 million-trip mark and already operates rental stations in Arlington County and Alexandria.

Bike commuting, though, remains concentrated in the District and in high-density inner suburbs . Farther out, in the suburban sprawl, cyclists have to contend with vehicles traveling at higher speeds than they do in urban areas as well as with longer distances and a lack of bike facilities.

Fort Washington resident Jim Hudnall has for years advocated more connections between trails in the Maryland suburbs. He said more bike lanes are necessary to make the Wilson Bridge trail and similar trails accessible. Hudnall said that for him, the most challenging part of using the bridge trail is sharing the road with cars in the two miles between his home and the bridge.

“What we want to do is take the existing trails and get them connected with bike lanes so people can easily go from Fort Washington to Alexandria,” said Hudnall, a leader in the Oxon Hill Bicycle and Trail Club, which has more than 400 members. “With bike lanes, it would be a very comfortable, doable ride for many folks.”

Right now, the Wilson Bridge trail provides a connection only to National Harbor on the Maryland side, but that could change soon. The county is renovating Oxon Hill Road, and, as part of the project, bike lanes will be added to the heavily trafficked county road, which connects residential communities to the Wilson Bridge.

For now, the views of the Washington memorials and the connection to trails in Northern Virginia are what make the bridge popular with pedestrians and cyclists, Hudnall said. His club uses the trail regularly for club rides, he said, and national organizations have used it as part of larger rides in the Washington area.

In the past year alone, trail usage picked up by about 10 percent in the area where the bridge trail meets the Mount VernonTrail, the second-busiest location for bicycles and pedestrians in Alexandria, said Carrie Sanders, manager of the city’s pedestrian and bicycle program. Many of the riders are crossing over from Prince George’s, she said.

Janell Saunders, 51, said a bonus for bike commuters is being able to speed past the heavy Wilson Bridge traffic during rush hour. Most workdays, Saunders drives to the Oxon Hill Park and Ride from her home in Charles County and bikes from there to District, where she works for the FBI. When she drives or takes public transit all the way to the office, the commute is less predictable and sometimes longer, she said.

“I hate to say this, but when I go across the Woodrow Wilson Bridge and I see how backed up it is, I actually start feeling a little superior,” she said. “I see drivers just being frustrated . . . and I just feel like I am already doing some exercise and they are seating in their car.”

Willis, the bike commuter who works at Fort Belvoir, said seeing her doctor write “obese white female” for her medical records may have pushed her to start biking four years ago. But the spectacular views of Washington, Reagan National Airport and the Potomac have kept her on two wheels.

“In the morning, when you are riding and you see the sun rise, it is absolutely beautiful,” said Willis, a survey statistician for the Army. “You couldn’t have asked for a better commute.”