Adding a shared-use path for pedestrians and cyclists on the Chesapeake Bay Bridge’s future replacement could bump the overall project cost by more than $1 billion, according to officials from the Maryland Transportation Authority.

During a presentation to the authority’s board Thursday, MDTA Director of Planning and Program Development Melissa Williams said preliminary estimates for the replacement of the two Bay Bridge spans vary from $14.8 billion to $16.4 billion without a shared-use path. With a lane for foot and bike traffic, those estimates rise to $16.1 billion to $17.6 billion.

That’s more than double the preliminary estimate of $7.8 billion presented at public meetings last year.

The board voted to mint the larger plan to build two four-lane spans to replace the aging Bay Bridge as the “state-preferred alternative,” which will advance now for further environmental review before federal approval.

It was the most modest of six replacement options, cementing a total of eight traffic lanes over the Chesapeake instead of other proposals to build 10 and widen the roads that approach the spans from shore.

The proposal to add a shared-use path to the bridge is a generally popular idea with Marylanders, but the added cost could leave it vulnerable to the chopping block amid skyrocketing nationwide construction costs.

After all, former Gov. Larry Hogan axed a shared-used path from the Harry W. Nice Bridge carrying U.S. 301 over the Potomac River, citing its cost.

“Will we in turn do some sort of cost-benefit analysis to determine if that’s a viable add to the potential construction of this new bridge?” board member Dontae Carroll asked.

Williams responded that the team would continue to do analyses to find ways to reduce costs.

Before approval, board member Mario Gangemi asked to clarify whether they were voting on the inclusion of the shared-use path or simply committing to further study of it as part of the larger replacement proposal.

“We are committing to additional study,” Williams responded.

Williams stressed that cost proposals and timelines are preliminary. A more precise cost estimate will emerge once the MDTA moves forward on designing the replacement spans, which likely won’t begin until 2028. If all goes to plan, construction could begin in 2032, she said.

Shared-use paths are generally at least 8 feet wide, per federal guidelines, but tend to be wider when built along major roadways or bridges, or forecast to accommodate more people.

Planners are proposing building the new bridges with 12-foot-wide travel lanes, a 12-foot inside shoulder and a 14-foot outside shoulder. Building a shared-use path would mean, essentially, adding another lane to one of the spans unless designers decide to repurpose one of the shoulders or travel lanes for it, which is unlikely. It would be separated from traffic by a physical safety barrier.

The MDTA may, however, be required to include the shared-use path because of a statewide Complete Streets policy signed by the Maryland Department of Transportation last year. The policy is meant to ensure roadways are safely designed for all possible users and emphasizes better access for public transit, pedestrians and cyclists.

In a phone interview after Thursday’s meeting, Williams confirmed that the MDTA is subject to the Complete Streets policy but could pursue a waiver if it deems the shared-use path doesn’t make sense to build.