The MassDOT Board of Directors has approved their updated five-year capital investment plan and included in the $18.5 billion proposal is a rather sizable stake into the much-needed reconstruction of Cape Cod’s dilapidated bridges.

The unanimously approved plan would send $1.09 billion toward the bridge construction project over the next five fiscal years, with most of the money set for use in the construction of a new Sagamore Bridge.

Both that span and the Bourne Bridge are in urgent need of replacement, according to assessments offered by the Army Corps of Engineers.

Allocating this money isn’t just an investment into the safety of the people who use the 90-year-old bridges, according to the state’s transportation chief, but a down payment into the welfare of all Bay State residents.

“Every transportation investment is an investment in people — connecting them to jobs, schools, healthcare, and each other,” Transportation Secretary and CEO Monica Tibbits-Nutt said.

After crediting her boss, Gov. Maura Healey, for supporting infrastructure spending, the secretary said the investment represents the Healey administration’s “shared priorities and gives us the tools to keep building a more connected, equitable Massachusetts.”

The cost for replacing both Cape bridges with new twin-bridge structures is estimated to be upwards of $4.5 billion, and replacing the Sagamore alone represents about half — or around $2.1 billion — of that total.

Shortly after taking office, Healey ordered that the original plan to construct both bridges simultaneously should be set aside in favor of a phased project which will see the Sagamore built first.

The state has already secured $2.3 billion in commitments toward the cost of the overall project, of which $1.72 million would be federal grant funding including $993 million in Bridge Project Grants from the Federal Highway Administration’s Bridge Investment Program and $372 million in Department of Transportation Mega Grant Funds.

A further $571 million in state bond funds and $350 million in federal appropriations rounds out the rest of the committed funding.

The aging bridges were built in 1935 and are owned, operated, and maintained by the U.S. Army Corps of Engineers. Preparatory groundwork began earlier this year and construction is slated to begin in 2027.

Not completing the project would itself be expensive, according to the Army Corps, with an estimated $775 million in upkeep costs expected over the next 50 years to go along with economic impacts of ongoing lane restrictions and outright closures.

The two bridges provide the only roadway connection on and off Cape Cod for the 263,000 residents of the Cape and Islands, as well as for 5 million annual visitors.

The Capital Investment Plan approved by the board also includes: $1 billion for the state’s Chapter 90 program, $424 million for the I-90 Allston Multimodal project, $276 million for the New Bedford I-195 to Route 18 interchange rehabilitation project, and $269 million to support the replacement of Lowell’s Rourke Bridge, among other major planned investments.