Itching to cross Portland's new picturesque bridge over the Willamette River?

You'll get your first chance on Aug. 9, 2015. (Note: That's next year, not next week)

TriMet says it will open the 1,720-foot Tilikum Crossing to bicyclists and pedestrians for one day in honor of the Providence Bridge Pedal's 20th anniversary. The span will then be closed until the MAX Orange Line begins operating a month later.

Rick Bauman, director of the Bridge Pedal, told The Oregonian that people registered for next year's massive river-crossing bicycling event will get the first birds-eye view from the deck of one of the nation's car-free bridges.

"When TriMet contacted me about the idea of doing this," Bauman said, "it took me about seven milliseconds to jump at the opportunity. The bridge is such a stunning piece of architecture and I know a lot of people are excited to cross it."

In a spray of brilliant white cables, the Tilikum Crossing -- the cornerstone of the $1.5 billion MAX Orange Line from Portland to Milwaukie -- has taken shape above the river and from the banks of the Willamette between the Marquam and Ross Island bridges.

TriMet says it will be the first multi-modal bridge in the U.S. to carry light rail and streetcar trains, buses, bikes and pedestrians, but no private automobiles.

From a distance, the $134 million cable-stayed structure -- the first new span built over the Willamette in Portland since the Fremont Bridge opened in 1973 -- looks nearly done. But Oregon's largest mass transit agency said there are still months of construction ahead.

What's more, more than 1,400 train and bus operators have to be trained on how to maneuver the Tilikum's transit lanes and the stops at each end, said Roberta Altstadt, a TriMet spokeswoman.

"We thought this would be an exciting opportunity to introduce the bridge to more than just commuters," Altstadt said. "This is a sneak peek."

Of course, Bauman said, TriMet was also motivated by concerns that the community's high anticipation about the bridge's opening would cause thousands of people to clog its paths on opening day, possibly causing disruptions or safety hazards.

"They felt the need to do something like this before the official opening," he said.

Following the 2015 Providence Bridge Pedal, which should end about noon, TriMet will keep the Tilikum Crossing open to the public for several hours. TriMet will stop bus, train and streetcar training for the day.

Altstadt said TriMet will use one-day bridge preview to prepare for crowds during the official opening.

The bridge and Orange Line are scheduled to open simultaneously on Sept. 12.

-- Joseph Rose