For the first time since 2011, Portland is bringing its Sunday Parkways street fair and bike and pedestrian loop to downtown.

This Sunday, tens of thousands of cyclists and pedestrians are expected to participate in the third event of the season. City officials shut down roads to motorized vehicles and freight, and set up family-friendly events, live music and free games along the route.

The 6-mile loop will also include close-in eastside neighborhoods. The Portland Trail Blazers are participating in the event and will host 3-on-3 basketball and other activities at the Moda Center.

"This could be one of the biggest Sunday Parkways ever," said Dylan Rivera, Portland transportation bureau spokesman. "We think we'll attract people from all over the city and the region."

Sunday Parkways, which is in its 11th year, typically draws 15,000 to 20,000 participants to each stop.

The first-of-its-kind route also coincides with the weeks-long Interstates 84 and 5 interchange closures. Sunday's event lasts from 11 a.m. to 4 p.m., but it will involve street closures through key areas of the city where drivers may be diverting from the freeways to seek relief on city streets.

Rivera said the city was "definitely aware" of the ramp closures, but he expects the city road crews and police presence will help manage the situation.

Transportation leaders plan a Tuesday news conference to spread the word about the route, which heads through the South Waterfront, Park Blocks, Rose Quarter, Lloyd District and Central Eastside Industrial district.

The route follows the 6-mile path of what city leaders hope will eventually be known as the "Green Loop."

Portland codified plans for the loop into its official planning documents this year. It's envisioned as a multi-use path that will give pedestrians and cyclists a safe place to get around.

According to its new Green Loop website, the city hasn't fleshed out a potential price tag, but a similar project in Indianapolis totaled $8 million per mile. "While specific funding resources for the Green Loop have not been determined, the project will require its own fundraising campaign," according to the project's website.

The Sullivan's Gulch Crossing, a pedestrian and bike-only bridge expected to break ground in 2019, is a key connection on the Green Loop that will eventually span I-84.

Much of the Green Loop isn't all that green in the Central Eastside at the moment.

Portland planning officials said the project "may involve repurposing some public space (streets or parts of them) into open space," down the line, "which would create more opportunities for trees and help us address climate resiliency and storm water management at the same time."

Here's a map of the route and various events along the way.