When the new Vikings stadium opens in 2016, transit officials worry about the proximity of about 65,000 football fans to the light-rail station just outside its front door.

To alleviate congestion and ensure safety, Metro Transit and the Minnesota Sports Facilities Authority, which is overseeing construction of the $1 billion stadium, have proposed a pedestrian bridge spanning Chicago Avenue S.

The $8.7 million walkway would extend from the stadium, stretch over the light-rail tracks and deposit pedestrians on a nearby public plaza, presumably out of harm’s way.

“Even with the Metrodome, people crossing the tracks has been a concern,” said Michele Kelm-Helgen, chairwoman of the Sports Facilities Authority. “Now with the additional transit line, it could be a somewhat dangerous situation, certainly for Vikings games and for the many other big events we’re planning.”

The situation will likely get dicier once Southwest light-rail service begins in 2019, and when the Blue Line (or Bottineau) is extended to Brooklyn Park two years later. More light-rail service means more trains traversing Downtown East — and more people.

As additional lines are developed, Metro Transit expects a train to pass through the intersection of 4th Street and Chicago Avenue an average of every two minutes on Vikings game days.

Last year, about 6,700 Vikings fans, about 10 percent, took light rail to games. The two Vikings games played at TCF Bank Stadium at the University of Minnesota this season saw 20 percent of attendees taking the new Green Line, which connects the downtowns of Minneapolis and St. Paul and stops at Stadium Village.

Once all four light-rail lines are in service, that figure could jump to 40 percent of game-goers, Metro Transit spokesman Drew Kerr said.

Metro Transit will issue requests for proposals for the pedestrian bridge by mid-September, with construction beginning as early as summer 2015.

The transit agency will likely devote $6 million from its coffers for the project — a figure that could be offset by federal grants — with the stadium authority pitching in $2 million, and the rest coming from bonds issued by the Met Council, the regional planning agency.

The Sports Facilities Authority purchased the Downtown East plaza from a private developer last year for $17.1 million. The authority’s contribution for the pedestrian bridge will pay for leveling the northwestern portion of the plaza to make way for public use, Kelm-Helgen said.

At one point, when the city owned the plaza and its underground parking lot, there was talk of building a hotel on the site, but further development there is not in the works, she said.

The $400 million Downtown East mixed-use project, now under construction two blocks away, will also bring hundreds of new office workers from Wells Fargo & Co. and apartment dwellers to the area, as well. That project calls for two office towers, apartments, retail and restaurant space, and a nearly two-block public park.

Other stadiums around the country, including Citi Field in New York, M&T Bank Stadium in Baltimore, and MetLife Stadium in East Rutherford, N.J., have similar pedestrian bridges.