It’s finally time to say goodbye to the old Northern Avenue bridge.
The 640-foot span over the Fort Point Channel opened more than a century ago, a compressed air-powered swing bridge that swiveled out of the way for ships that trawled the waterway in what was then a hotbed of industry.
The people who worked Fort Point’s wharves and warehouses at the start of the 20th century would not recognize the Seaport of today: a glitzy expanse of multimillion-dollar condos, swanky glass offices, and pricey restaurants. The blue-collar work has been shunted to one side of the peninsula, corralled in an army base-turned-industrial park. Through all the transformation, the Northern Avenue bridge endured — though not for much longer. The bridge has been rotting away, as things do without proper care and attention. First, the bridge was closed for cars in 1997. Then, it was fenced off for bikes and pedestrians in 2014.
Through various administrations — Mayors Menino, Walsh, now Wu — city officials wrestled with the best way to reinvigorate or replace it. Now, this important vestige of the waterfront’s industrial past is heading for the scrap heap.
Last year, Mayor Michelle Wu’s administration received an updated assessment of the bridge’s structural integrity, and the picture wasn’t pretty. City officials decided to remove the superstructure, as it’s called, to protect the safety of the Fort Point Channel waterway, and they have no immediate plans to replace it.
So the city’s Public Works Department is advancing plans to break it apart and load the pieces onto barges to a waterfront staging area behind the Leader Bank Pavilion, for disassembly and paint removal. The concrete masonry piers that hold up the bridge would stay. The holes in the iron girders that support the bridge are getting so big, the Massachusetts Historical Commission has signaled it’s fine with the demolition plans; better to take it apart now before pieces fall into the channel.
In December, the commission’s lead historic preservation officer asked city officials to update the paperwork, to reflect the fact that a fancy replacement that was envisioned in 2020 under then-mayor Marty Walsh is on hold. The city has budgeted $31 million so far for dealing with the bridge, including $9 million that’s already been spent on design and engineering work. The Wu administration hopes to start demolition later this year, pending the necessary permit approvals from the US Army Corps of Engineers and other agencies, and says it could cost at least $20 million.
About that fancy replacement: The public debate that led to its design reflected the broader tug of war in Boston between prioritizing cyclists and pedestrians and ensuring car traffic flows unimpeded. The end result was an attempt to balance the two: the new bridge would be reinforced enough to support cars and trucks but limited to emergency vehicles and buses that serve the Seaport. (Many of the Seaport shuttles to North Station have since been replaced by ferry service.) The price tag kept climbing, to $100 million or more. Now, those plans are getting shelved.
However, the idea of building a new span across the mouth of the Fort Point Channel lives on.
Enter John Sullivan, the chief engineer of the Boston Water and Sewer Commission. He’s been floating an idea for more than three years to build a barrier with movable gates at the channel’s entrance, to keep storm surges out and to hold rainwater in. It’s by far the most expensive element of a much broader effort by Boston Water and Sewer to address pain points throughout the city’s stormwater system.
At first glance, this Fort Point concept might seem a little crazy. But Sullivan, a practical guy, makes a persuasive case. Fort Point Channel is a nexus for a wide range of storm pipes that snake out to downtown, South Boston, and the South End. If a heavy rain hits with a storm surge at high tide, that whole network might be overrun. Sullivan’s concept would only close the floodgates at low tide if severe weather is in the forecast; the gates would then create a giant bathtub that could hold up to 160 million gallons of water as the tide rises. The water can then be released or pumped out, as the tide recedes, to avoid flooding of the properties near the channel and to protect hundreds of acres from watery devastation.
Sullivan said his team had a three-hour conversation last month with the Army Corps, which is in the midst of a thorough review of the Boston coastline’s resiliency, and the federal agency seems to be warming up to this concept. If it moves forward, he said, the agency might end up paying for as much as two-thirds of the cost. That’s important, especially when you size up the potential price tag: up to $767 million for submerged gates that would stay on the ocean floor and only be raised to shut the channel during bad storms. The project is not as far-fetched as it might seem: A similar barrier was installed in the 1960s at the mouth of the Providence River, protecting Rhode Island’s capital city.
This new Fort Point Channel barrier also would provide a logical foundation for a new footbridge, either to the north of what’s left of the Northern Avenue bridge, or roughly in its existing footprint. The schematics on file at Boston Water and Sewer assume a harbor walk would be part of any dam design. (Fortifying the structure to accommodate cars can be done, but it would drive up the costs.)
Sullivan knows federal money is tight right now. Not to worry. Permitting a project of this scope could take up to five years. He doesn’t expect construction to begin until the 2030s. The original conclusion in City Hall a few years ago was that the floodgates couldn’t be worked into the official Northern Avenue bridge replacement project. Now that city officials are receptive to other scenarios, Sullivan said, he is hopeful about gaining traction with this combo project: a bridge above, and floodgates below.
Restoring pedestrian and bike access across the channel would be welcomed by employers in the area, said Patrick Sullivan, head of the Seaport Transportation Management Association. While his group supported the compromise concept from five years ago that’s now in limbo, he says some members are relieved that city officials are moving ahead with the demolition for safety reasons.
The old bridge turned out to be just the right infrastructure for the Fort Point Channel at the dawn of the 20th century, to keep industry there humming along. With climate change posing an ever-increasing threat to low-lying coastal cities like Boston, these floodgates might end up as just the right project to protect the channel and its commerce for the rest of the 21st century, and beyond.
Jon Chesto can be reached at jon.chesto@globe.com.
