After years of debate and months of suspense, an often-divided Bellevue City Council put its differences aside Monday night and unanimously approved an agreement with Sound Transit for a light-rail route that tunnels through downtown.

The 7-0 vote finalizes an agreement on the East Link rail route and funding for the downtown tunnel.

The agreement allows Sound Transit to complete design of the approximately $2.7 billion, 14.5-mile line that will connect Seattle, Mercer Island, Bellevue and Redmond. Passenger service is expected to start in 2023.

"We pushed it as far as we can," said Councilman Kevin Wallace, who was part of a council majority that for a year and a half fought Sound Transit's preferred route south of downtown. "We have a choice. We can cooperate with Sound Transit and the rest of the region to deliver on this project, or we can fight. I think the answer is we've got to cooperate."

"It's not perfect," said Councilwoman Jennifer Robertson, who also has been critical of the transit agency, "but it makes sure that we do have a tunnel, and it gets us into the project where we're working with Sound Transit to reduce the cost and do mitigation."

The council's action ratifies Sound Transit's preferred route along Bellevue Way Southeast and 112th Avenue Southeast, through downtown, and on through the Bel-Red Corridor to the Overlake area of Redmond.

Bellevue agreed to share the cost of the tunnel, but last-minute changes in the agreement commit the city and Sound Transit to jointly find ways to cut the costs. Robertson and Wallace said they hoped the city's maximum cash and in-kind contributions could be reduced from $160 million to $100 million.

Even with those cost cuts, Robertson said, she advocates putting a property-tax increase before voters next year to pay for the tunnel.

Councilman John Chelminiak, a strong supporter of Sound Transit's planned route, said, "I've been around government for quite a long time in this area, and there are rare moments when people sitting on a board have an opportunity to make a decision of this magnitude and a decision that leaves an incredible legacy in the community. Tonight is one of them."

King County Executive Dow Constantine, a Sound Transit board member who was involved in negotiations with Bellevue, said in a statement: "Bellevue voters have consistently supported the expansion of light rail as a way to link businesses, residential neighborhoods, and cities throughout our region.

"Tonight's vote reflects the negotiated outcome between Bellevue and Sound Transit that brings us one step closer to construction."

Bellevue and Sound Transit negotiated the agreement after a city study showed that an alternate route sought by a council majority was beyond Sound Transit's budget. The alternate route would have crossed Mercer Slough near the Interstate 90 bridge and followed an abandoned rail corridor to downtown.

Wallace said residents of Enatai and other neighborhoods next to the planned track are "unduly impacted by this thing. I can only apologize that there's no solution that's better than the one in front of us."

Sound Transit spokesman Geoff Patrick said in an email that agency CEO Joni Earl expects to sign the agreement after a final check of the language adopted by the City Council. The Sound Transit board last month authorized her to sign the agreement.

Keith Ervin: 206-464-2105 or kervin@seattletimes.com