Leaders in Minneapolis are seeking big ideas on how to reshape the city's signature pedestrian boulevard, Nicollet Mall, in preparation for its most significant overhaul in nearly a quarter-century.

Last rebuilt in 1990, Nicollet Mall's design has been largely unchanged since it was originally opened in 1967. The city wants $20 million in state bonding funds for a wholesale reconstruction, but officials aren't waiting for the money to chart a new design. On Tuesday, staffers briefed the City Council on a design competition for the corridor that will take place this summer.

Nicollet is unlike any other street in Minnesota. On summer afternoons it is a bustling stream of downtown workers, who crisscross roads reserved for taxis and buses, eat lunch outside and frequent the street-level retail outlets that line the avenue. But its tiles are deteriorating, a failed heating system leaves the street slippery in the winter and the avenue's design is out of date with its current uses, city staffers say.

Mayor R.T. Rybak made Nicollet a focal point of his last State of the City speech last week, imagining "Nicollet Green" as a park in the center of the city peppered with sidewalk cafes and heated by steam from the county garbage burner.

"This generation needs to do what was done back in the '60s, which is to reinvent the urban pedestrian experience," he said Tuesday. "So we're going to get the best minds from here and elsewhere to give us several versions of what the next wave of great American streets can be."

City officials say the project will cost $30 million to $40 million. It will be paid for by the yet-unapproved state bonding dollars and assessments on nearby building owners. Rybak said the bonding dollars are "critical. Right now we have no plan B."

The design competition will begin when the city chooses four consultants in coming months. Those four teams will then present their visions of Nicollet to the public in August, before an implementation committee recommends one for City Council approval by September. The committee consists of three city leaders, two community members and four downtown business representatives.

Transforming Nicollet was one of 10 goals that the Downtown Council, which represents downtown businesses, identified in its 2025 plan last year. The group's president, Mark Stenglein, said his membership knows there is "some kind of an ask coming" in the form of assessments, though the details remain unclear.

"In order to make downtown vibrant ... we can't just charge them out of the ballpark," he said, noting that the cost will be passed on to tenants and store customers. He also believes the $30 million estimate is high, since the underground portion of the street was rebuilt in 1990.

The 2025 plan said that Nicollet should become a curb-free walking experience with public plazas featuring "art pieces, water features, dramatic lighting, interactive programming and other attractions."

The state bonding dollars remain in limbo, however. Gov. Mark Dayton included $20 million for Nicollet Mall renovations in his bonding recommendations, but the project was not included in the House legislation. The House bill includes $50 million for a Metropolitan Council transit improvement program, which the city would have to apply for. The Senate bonding bill has not been released.

At the Tuesday hearing, Council Member Betsy Hodges said the future design of Nicollet should accommodate the effects of climate change. "We are going to be wetter and colder and hotter and drier 20 and 50 years from now. And this mall is going to have to be able to accommodate that," said Hodges, who is running for mayor.

Council Member Sandy Colvin Roy, who chairs the city's transportation and public works committee, added that Nicollet Mall should lose the "mall." It's retro, she said, but "not retro enough to be cool."