BOSTON OFFICIALS SAY they intend to go full speed ahead with rebuilding Long Island Bridge as a path to an addiction recovery center on the harbor island and claim their approach to construction will minimize heavy traffic through Quincy’s streets and mitigate that city’s concerns over public safety.

Chris Osgood, Boston’s chief of streets, said the city will build the sections of the planned $92 million bridge on shore then float the pieces out to the existing stanchions to put into place.

“This will minimize disruption,” Osgood told reporters in a briefing to go over Mayor Marty Walsh’s plan to submit his Notice of Intent to the Conservation Commission, the first concrete step in getting approval reconstructing the span. “We want to be able to work with our partners in Quincy.”

With the filing, Boston officials plan to begin construction next year and should complete it by 2021. Osgood said the bridge is being built to last 75 years. Osgood said Boston officials will also file plans with the Quincy Conservation Commission and will engage officials in the City of Presidents in talks going forward. But a spokesman for Quincy Mayor Thomas Koch said while he is “always open to discussions” with Walsh, Koch will not budge on his opposition to a rebuilt Long Island Bridge.

“Mayor Koch has a great deal of respect and a great relationship with Mayor Walsh,” said Koch spokesman Christopher Walker. “But if the conversation is going to start and end with ‘We’re building a bridge,’ we’re going to have to find something else to talk about. The bridge is a nonstarter.”

Quincy City Councilor Anne Mahoney, who has submitted public records requests to Walsh about the city’s plans to rebuild the bridge, said Boston has not engaged its neighbor to the south despite the claim the recovery center will be a regional facility.

“They should engage in conversations with us,” said Mahoney. “They’re not being neighborly. They haven’t shown us anything, basically boycotted my [records request]. This is an opportunity for Quincy to have a say. They have come through our roads but they haven’t even picked up the telephone to tell us what their intentions are.”

The bridge has long been a point of contention between the neighboring cities. While Long Island is in Boston, the only access by vehicle is through Quincy. In 2014, Walsh closed the bridge, first opened in 1951, and ordered it to be dismantled after state officials declared it unsafe. Walsh was forced to relocate all the social services programs, including the homeless shelter and addiction treatment programs, to move back into the city.

There was little discussion for years and Quincy officials were convinced Walsh had abandoned plans to rebuild the structure. But in January, Walsh announced he would put a new bridge in place and build a full campus on the island dedicated to addiction treatment and recovery. Walsh, a recovering alcoholic, said the bridge is essential in fulfilling the vision of having a full-service recovery center not just for Boston residents but for the region.

“For many people, including myself, Long Island played a vital role in Boston’s recovery landscape — and it will again,” Walsh said in a statement “Tackling the opioid crisis means using each and every tool we have, and this is an important next step to ensure Long Island can serve as a resource for those in Boston, and those from surrounding areas, who are struggling with substance use disorders.”

Some advocates claim Quincy’s opposition is a case of “NIMBYism” and residents of the Squantum neighborhood don’t want addicts traveling through their streets.

But Koch and others say they support using the island for that purpose but would rather see alternatives to the bridge, such as a ferry, to bring people to and from Long Island. The Quincy City Council is considering a measure that would restrict heavy vehicles such as construction trucks and buses from traveling along the causeway connecting Squantum with Moon Island. They suspect there’s something other than just recovery on Boston’s agenda, such as potential private development, a suspicion Boston officials dismiss.

“If they were really serious about a recovery center, they could take that $100 million and get one up and running and use a ferry service in a matter of months, not years,” said Quincy City Councilor William Harris, who lives in and represents Squantum. “When the bridge came down, I never thought they would try to build it again. There has to be an ulterior motive.”

Marty Martinez, the chief of Health and Human Services in Boston, said the only motive is to deal with the addiction crisis as soon and as effectively as possible. He said Walsh has earmarked $1 million to study the condition of the buildings on the island to see if they can be repaired or need to be replaced. No health or recovery officials could give an estimate for how many beds would be needed on the island or what the annual operating costs would be. They project that the services will be a combination of city-operated and private programs.

“We know today there’s not enough beds for people,” Martinez told reporters. “For us it’s about access and equity. We can’t wait for us to do an assessment of whether we could find a place [on land]. We’re fighting an epidemic, we’re fighting a huge issue.”

Martinez and Osgood both dismissed the ferry option, saying the unpredictable weather in the region could make regular transports difficult as well as hamper the need for emergency evacuations for health or safety reasons. But Quincy officials said that view has been the problem from the outset.

“That’s the issue – they just dismiss it,” said Walker, Koch’s spokesman. “We would like to see some effort put into it. They’ve dismissed it, they haven’t proved it. They only say it’s not viable.”