One of the most frenetic spots in the city could soon be home to thousands of new residents and office workers.

Houston-based Hines is putting the final touches on plans to build a mixed-use development on the edge of downtown Minneapolis that would include a 36-story apartment tower with 450 rental apartments and a 14-story, 340,000-square-foot office tower.

The high-density, transit-oriented project aims to connect the trendy North Loop neighborhood to the city's skyscraper-dotted Central Business District (CBD). Planners said the project will "create an urban oasis" at what is now a crossroads for cars, trains, people, buses and bikers.

"That's a harsh pedestrian landscape as it exists today," said Robert Pfefferle, director of development for Hines' Minneapolis office. "This will knit the fabric of the city back together again."

Hines expects to begin submitting plans to neighborhood groups and the city this week.

Called North Loop Green (NLG), the project would include several paths connecting pedestrians and cyclists to the Cedar Lake Trail, and several elevated gathering spaces, including a rooftop restaurant-bar and a sky-high "amenity bridge" between the two buildings that will give workers and residents views of the downtown skyline.

"In Chicago there are a number of places that have that, and they've been highly successful," said Pfefferle. "We think it's a great opportunity to bring something like that here."

The proposal is the third and final phase for a 6-acre parcel the company acquired in July 2012 for $13.7 million. The site is bordered by N. 5th Street, N. 3rd Avenue, Washington Avenue, the Northstar Rail Line and the Cedar Lake Trail. When it was purchased, the parcel included several surface parking lots and the vintage Union Plaza building on a block that is adjacent to a public park, Target Field and a busy transit hub that serves several commuter rail lines.

The first phase of the project, the Dock Street Flats apartments, was followed by the seven-story T3 office building. The new buildings will take their design cues from the sleek, shimmering office towers in the CBD, and the brick and timber buildings and rail yards that once served the Warehouse District.

"You'll get a handmade feel from the bones and DNA of the North Loop, and a sense of refinement from the crisp edges of the materials that relate back to the buildings of CBD," said Aaron Roseth, principal and president of ESG Architects, which is designing the project.

The 36-story tower would include about 360 market-rate rentals and 90 short-term rental units aimed at travelers, workers and others who don't want a long-term lease commitment. Each component will have a dedicated lobby, but will share amenities. The scale of the project enables designers to include amenities that aren't feasible in a smaller project, said Roseth.

Pfefferle said the 14-story multitenant office building can accommodate a sizable tenant, but he anticipates that there will be a mix of tenants and uses.

The towers will be connected by a full-floor bridge that will span the 17th floor of the apartment tower and the 14th floor of the office tower. Roseth said the floor-to-floor heights in each tower are different, which allows the extra floors in the residential tower. The bridge will house 5,000 square feet of indoor and outdoor space for a restaurant and/or bar. There will also be a rooftop gathering space, and 15,000 square feet of restaurant and retail space on the plaza level.

New plazas, paths and a "grand staircase" will make it easier for pedestrians and bikers to move through the site from all sides, eliminating some of the physical barriers that now exist.

"We want to make it a destination, but also a safe pedestrian thoroughfare between the CBD and the North Loop," Roseth said.

During the yearslong planning process, Hines has been consulting with a variety of constituents to help shape the project.

Dan Collison, executive director of NuLoop Partners, a public-private partnership that promotes and guides development in the area, said that while he laments the deepening lack of affordable-housing options in the area, the proposal is consistent with the city's desire to increase density and create better access to public transportation and trails. Those are improvements, he said, that will provide a broad range of benefits in the area.

"It feels like an appropriate response," he said. "It's innovative in a space that's begging for innovation."

Apartment rents will be market-rate.

The average rent for a one-bedroom apartment in downtown Minneapolis during the first quarter was $1,530, according to Marquette Advisors.

Hines selected Minneapolis-based ESG Architecture and Design to design the project after conducting a national search. For ESG, Roseth called it a game-changer.

The project is by far the biggest — and most complex — for the firm. It will also be the firm's new home. ESG plans to move about 175 of its employees from its current home near the Guthrie Theater in the Mill District to the building in late 2022. That move comes shortly after the retirement and divestment of the remaining founders, representing a new era for the firm's younger partners.

"To me, this project is a symbol of that next step," he said. "And we look at it as a next step for the types of projects we want to do."

Staff writer Nicole Norfleet contributed to this report.