For nearly six decades, Boston politicians have avoided a wholesale overhaul of the city’s zoning code, a minefield of arcane rules that dictate what can be built and where.

On Wednesday, Boston Mayor Michelle Wu stepped into it.

In a speech to business leaders, Wu announced plans to reform the code, streamlining the dense and dizzying process required to propose, approve, and build new real estate projects and, she hopes, making it easier to tackle the massive housing shortage along the way.

It’s an ambitious objective, and one likely to face fierce pushback from neighborhood groups, civic associations, and other interests that have long used the lengthy permitting and review process to chisel down, or block entirely, projects they dislike.

“It’s a major endeavor that will take a lot of sustained work,’’ Wu said Wednesday following a speech to the Greater Boston Chamber of Commerce. “It’s taken a while to get the staffing in place and to get the organizational structures ready . . . and then to be at a point where we can really take on and sustain the level of community engagement that’s necessary to reach the new system that we’re building.’’

The overhaul will start with shifting from the current approach in which planning efforts focus on entire neighborhoods, to a “squares and streets’’ model that aims to create mixed-use hubs along main corridors near transit stations. It’s something the Wu administration can largely enact on its own, with approvals by the board of the Boston Planning & Development Agency and the Zoning Commission.

Meanwhile, the BPDA will create teams focused on zoning reform and compliance, so that fewer projects would need a variance — a time-consuming and often-unpredictable process that critics say stalls too many developments in their tracks.

The zoning overhaul will be guided by a report from Sara C. Bronin, a professor at Cornell University’s School of Art, Architecture, and Planning and founder of the National Zoning Atlas project, which dubs Boston’s current zoning code “bloated, outdated, inconsistent, and inequitable.’’ The sheer size of the code vastly outstrips cities of similar size across the country, some 4,000 pages here compared to 1,830 in Portland, Ore., and just 349 in Nashville.

The complexity is driven in part by Boston’s “longstanding practice of neighborhood-specific zoning,’’ wrote Bronin, with 429 unique zoning districts governing land use and building types across the city’s nearly two dozen neighborhoods. Bronin suggests reducing that to 50 districts, which would still allow neighborhoods to retain their unique character and flavor while having more overall consistency in the code.

She also suggested culling the code to 500 pages and creating a new mixed-use district to “capitalize on transit stations’’ by allowing for offices, labs, residential, and other uses near MBTA stations — changes she acknowledged would require “a significant mindset shift.’’

“But neighborhoods, and the people who live and work in them,’’ Bronin added, “will be better off without convoluted, outdated code provisions interfering with their plans and their property rights.’’

Developers and housing advocates have long pushed to simplify Boston’s development approval process, and Wu’s proposals were greeted with applause at the Chamber breakfast Wednesday.

“Reducing red tape and encouraging housing creation across all price levels is a critical step Boston can take to address the housing crisis,’’ Greg Vasil, CEO of the Greater Boston Real Estate Board, said in a statement, praising Wu for “embracing much-needed zoning reforms that will streamline housing approval and for promoting different types of housing creation.’’

But the move — should it come to fruition — would represent a major change in a city where neighborhood and civic associations have long held substantial influence over what gets built on their turf. Much of that influence is wielded in meetings around zoning changes, either before the city’s Zoning Board of Appeal, which grants variances, or as part of BPDA development review.

And the proposal is likely to add fuel to debates already raging in communities like East Boston, where some residents have fiercely protested city rezoning proposals.

In Orient Heights, for example, BPDA director Arthur Jemison and other agency staff held a community meeting in March to discuss allowing accessory dwelling units for single- and two-family homes, along with allowing three-story buildings near the MBTA Blue Line station. The meeting boiled over into shouting. Some residents posted hand-drawn signs protesting the proposed changes. “Don’t Southie My Eastie,’’ said one; “We Will NOT be West Ended’’ said another; “We Never Asked For This!!’’ said a third.

Orient Heights is a rare section of East Boston that’s dominated by single-family homes. The neighborhood’s civic association believes zoning changes would lead to overdevelopment and altering the area’s “suburban feel’’ and existing homes.

“Most residents are already feeling the pain from the overdevelopment in the area,’’ Sean Calista, a board member of the neighborhood association, told the Globe on Wednesday. “If you take away the neighborhood-level planning, then we might start getting three-story buildings next to those homes.’’

The current zoning system gives power — sometimes amounting to veto power — to neighboring property owners, said Josh Zakim, a former Boston city councilor who’s now executive director of nonprofit Housing Forward-MA. Lawsuits challenging zoning variances are commonplace. Even when resolved, they often add time and cost to a project.

“Neighbors have a right to care about projects near them, and they have a right to have input. But they should not be able to hold up a three-decker or four-plex for 18 months because they’re worried about height,’’ Zakim said. “Right now, a well-resourced abutter who doesn’t want an affordable housing project near them can often litigate and hold up the project for years or just kill it entirely.’’

But even some neighborhood groups see the value of simplifying the zoning code. In many places around the city, two directly abutting parcels have different zoning parameters — a “silly’’ reality, said Anthony D’Isidoro, president of the Allston Civic Association and a member of a committee that advises Wu on the BPDA’s development-review process.

“It’s going to have to be a really solid sell on behalf of the city to get the community to buy in,’’ said D’Isidoro, whose group routinely negotiates with developers as projects move through city review. “Particularly in our neighborhood, it’s going to pit the traditionalists against the younger generation, which is more pro-development — and they’ll be considerable pushback from longtime residents who are familiar with their block and don’t want to see it change.’’

Catherine Carlock can be reached at catherine.carlock@globe.com. Follow her @bycathcarlock. Andrew Brinker can be reached at andrew.brinker@globe.com. Follow him @andrewnbrinker.