State transportation officials plan to completely replace the crumbling John J. Beades Bridge on Morrissey Boulevard as they continue to contemplate a large overhaul of the coastal roadway.

The replacement of the bridge, located by National Grid’s rainbow gas tank, received the green light to move into the design phase. Officials with the Massachusetts Department of Transportation (MassDOT) say a full replacement is likely necessary due to the age of the bridge, but caution that the project is years away from construction.

The six-lane span, which functions as a drawbridge to allow boats to pass in and out of Savin Hill Bay, last saw significant fixes in 2001. At the time, it was under the purview of the Metropolitan District Commission (MDC), which no longer exists. The agency was absorbed into the state Department of Conservation and Recreation years later.

First built in 1928, the drawbridge was named for a Dorchester state senator. A report from the MDC in 1998 said the bridge needed to be completely replaced, since it was only built to last for 50 years. But smaller fixes followed instead, with $1.3 million between 1995 and 1999, and then a $9.1 million renovation in 2001.

Problems continued as the drawbridge has sometimes stalled in the “up” position and caused traffic delays. The drawbridge’s breakdowns add to commuter frustrations, as drivers also Morrissey Boulevard’s frequent flooding.

A complete overhaul could cost $122 million, according to a posting on MassDOT’s website. The project has been assigned to Canadian engineering firm WSP.

MassDOT officials sent on Jan. 26 a letter to Jascha Franklin-Hodge, Mayor Wu’s chief of streets, saying the Beades Bridge is on a list of projects that have been evaluated and now considered eligible for federal highway funding. The letter notes that the eligibility determination is “not a commitment of state or federal funding to the project, nor is the decision to commit funding solely MassDOT’s.”

MassDOT sent a copy of the letter to local lawmakers, including state Sen. Nick Collins and state Rep. Dan Hunt, who both represent the area around Beades Bridge.

The other bridges on the list, according to the letter, are parts of I-93 that are close to Beades Bridge, the southern approach to the Tobin Bridge, and the deck replacements slated for Beacon Street above I-90 and Massachusetts Avenue over I-90 and MBTA tracks.

Asked about the letter, a MassDOT spokeswoman said the project will be coordinated with the ongoing planning efforts for Morrissey Boulevard. A state commission, created through a transportation bill signed by Gov. Charlie Baker last year, is expected to take a deep look at the Morrissey corridor, which is facing rising sea levels, thanks to climate change, while also seeing an influx of development up and down the main thoroughfare.

Rep. Hunt said the Beades Bridge project is in its infancy “but we would all advocate for it to continue to be a navigable waterway.” Hunt pointed to the Dorchester Yacht Club and other potential public moorings in the area.

But whether that means it remains a drawbridge, or a higher bridge to accommodate boats, remains to be seen. The bridge must also ensure that Savin Hill Bay has healthy swimming water, since some of the bridge’s bays are full of rocks and sediment, which block the bay from fully flushing out water after a high tide, according to Hunt.

“As I continue to advocate for the Morrissey project, the Beades Bridge is an important piece of that,” Hunt said.

The Morrissey commission, with the governor’s transportation and environment chiefs as its co-chairs, has not yet met. Since past efforts to remake the boulevard into a pedestrian-friendly roadway have fallen apart, commission members, including Hunt, want to set up the panel as a place “where everyone gets together and gets on the same page.”

Hunt noted that Gov. Maura Healey’s transportation secretary, Gina Fiandaca, had previously served as Boston’s transportation chief, and she is well-acquainted with the problems with Morrissey Boulevard and the troublesome rotary off I-93, Kosciuszko Circle.

“All parties at the table want to get this done,” he said.

The next steps for the Beades Bridge will be “to progress the design, develop estimates, and incorporate it into the MassDOT capital plan,” said the spokesperson, Kristen Pennucci. “At this point construction has not yet been funded nor has a date been assigned for construction.”

MassDOT expects construction won’t move ahead “any sooner than 2028.”

Executive editor Bill Forry contributed to this report.