PETERBOROUGH — Town officials plan to ask a court’s permission to hold a special town meeting to appropriate additional funds for the Main Street Bridge replacement project.

The select board voted Thursday to request the special meeting, according to a notice posted on the town website.

Voters appropriated $6.6 million for the bridge project at town meeting in May 2018. But the bid came back higher than anticipated, so town officials hope to ask for an additional $1.4 million in the special meeting.

Federal Highway Administration funds are to cover 80 percent of the project cost, with the town responsible for the other 20 percent. The town’s share of the additional appropriation would be $280,000.

“The engineer’s estimate of probable cost was $5.5 million, so we thought that a 20 percent buffer would be more than enough,” Town Administrator Rodney Bartlett said Monday.

But the actual bid was just under $6.6 million for construction alone, not counting administration, inspection and materials testing, he said. The town is asking for $785,000 to cover those costs plus additional funding to cover unanticipated expenses, resulting in the $1.4 million figure.

Built in 1940, the Main Street Bridge crosses the Contoocook River, connecting downtown to Route 202. Bartlett said it has been on the state’s “red list” of structurally deficient bridges since before 2006, and the weight limit had to be reduced in 2010.

Under state law, a town can ask a court to authorize a special town meeting when “an emergency arises requiring an immediate expenditure of money.”

Bartlett said waiting until Peterborough’s regularly scheduled town meeting in May 2020 would put the project “in a difficult position financially.” The bid could be withdrawn, and with it, the town would lose the federal funding commitment, he said.

The town would then have to look at lowering the weight limit again or conducting “remedial repairs” just to keep the bridge open, which would cost more in the long run, Bartlett said.

If approved, the town would have to notice the special meeting and hold a public hearing, a process that would take about a month, according to Bartlett.

“I’m hopeful we’re looking at mid-January for a date for the special town meeting,” he said.

That would allow construction, which is expected to take 18 months, to start in April or May, Bartlett said.

Paul Cuno-Booth can be reached at 352-1234, extension 1409, or Follow him on Twitter @PCunoBoothKS.