Maine and New Hampshire are expected to jointly pay $5 million to Pittsfield contractor Cianbro Corp. to settle its claim that inadequate design work created cost overruns and delayed the opening of a major bridge between the two states for months.

The payment caps a contract dispute about construction of the Sarah Mildred Long Bridge between Kittery and Portsmouth that has dragged on for more than a year.

The final price of the bridge that carries rail and vehicle traffic over the Piscataqua River was $181.2 million, about $4.5 million more than estimated two years ago. Maine and New Hampshire will share the added construction cost equally.

Cianbro earlier filed a request for an equitable adjustment asking to be compensated $16.9 million for cost overruns and time extensions due to deficiencies in the original bridge design, according to a memo sent this month from New Hampshire Department of Transportation to Gov. Chris Sununu and the executive council.

Cianbro agreed to accept an adjustment of $5 million after mediation.

“The Maine and New Hampshire departments of transportation have resolved Cianbro’s request for equitable adjustment regarding the Sarah Mildred Long Bridge project,” Maine DOT spokesman Paul Merrill said in a written statement.

“The agreed-upon amount represents less than 3 percent of the total project costs,” he said. “We’d like to thank the negotiators involved for their hard work to help the taxpayers of our two states avoid more costly litigation.”

The $4.5 million in added construction costs, plus the $5 million in Cianbro settlement costs, brings the total amount to settle the dispute to $9.5 million.

New Hampshire’s executive council is expected to vote Wednesday on its entire $4 million payment, including the $1.8 million it owes to settle the Cianbro adjustment claim. Maine is responsible for the remaining $5.5 million.

In response to an interview request and explanation for its initial settlement claim, Cianbro spokesman Scott Tompkins said the company declined to comment.

The bridge opened to traffic in March 2018, seven months behind schedule.

In the lead up to its opening, Maine Department of Transportation officials and Cianbro executives spent months trading blame for the delay. Communication between the company and state officials acquired by the Press Herald through a Freedom of Access Act request showed increasing frustration on both sides as repeated deadlines to open the bridge passed.

The state accused the company of violating its contract, removing key staff from the project and threatening to withdraw work. Underlying its message was a possible $1,000 per-day penalty for not delivering the bridge on time.

Cianbro argued the plans it was given had to be changed during construction, creating substantial delays and costing the company millions of dollars.

The Sarah Mildred Long Bridge is a lift-span bridge that can be raised and lowered for vessel travel over the river. The bridge replaced a span that was closed in August 2016 after the lift span got stuck in the open position. It was demolished two months later.

About 15,000 vehicles cross Route 1 over the bridge daily, and it is part of a three-bridge system between Kittery and Portsmouth maintained jointly by Maine and New Hampshire.

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