PORTSMOUTH — The Executive Council on Wednesday approved a $28.7 million payment to the state of Maine for New Hampshire's 46 percent share of construction costs to upgrade the Piscataqua River Bridge.

According to a memo to the council, by Department of Transportation Commissioner Victoria Sheehan, the "bridge preservation construction" project is to extend the life of the circa 1971 steel girder bridge, spanning Portsmouth to Kittery. Total cost of the project is $61.8 million and Maine is paying the balance, with the percentage split "based on the location of the state line and the portions of the bridge located in each state," the memo notes.

"The bridge is New Hampshire's highest priority preservation bridge," Sheehan wrote. "This project is the last in a series of high-profile projects to address the condition of the three bridges over the Piscataqua River between New Hampshire and Maine."

The plan calls for removing pavement from the bridge, "performing partial and full-depth deck repair as needed, installing new membrane and repaving the 1,344-foot main truss span, repaving the 1,810-foot New Hampshire approach span and the 1,344-foot Maine approach span," according to the DOT report.

Bridge rail will be replaced, except a portion previously replaced when sound barriers were added, the memo notes. The median barrier, drainage system and expansion joints will also be replaced, according to the plan.

"Maintenance of traffic is a significant issue," Sheehan reported to the council. "Much of the work will be required to be done in off-season periods, maintaining three lanes of traffic in each direction during summer months, with movable barrier to accommodate short duration, off peak lane closures."

The $28.7 million pays for New Hampshire's portion of engineering, design and construction, the report notes, while also citing affiliated costs for contingency, "possible incentives" and police officers.

Maine is the lead agency for the project and an agreement between the states notes that if costs exceed budget by 10 percent, the state's transportation officials will review and reconsider cost sharing.

The contract for the work was awarded to low bidder SPS New England, funds for New Hampshire's portion will come from the state transportation fund and is in the state's fiscal year 2019 budget, Sheehan wrote.

About 10 miles north, Maine DOT is building a new $40 million toll plaza in York and Maine Turnpike Authority spokeswoman Erin Courtney said in September three lanes of traffic will remain open at all times. Maine DOT spokesman Ted Talbot said at that time delays are expected during the Piscataqua River Bridge rehabilitation, but the state "will work to minimize the impacts to motorists."