KITTERY — The New Hampshire Department of Transportation and the Maine Department of Transportation have decided to permanently close to motor vehicle traffic the 76-year-old Sarah Mildred Long Bridge connecting Portsmouth, New Hampshire, and Kittery. This action follows a mechanical failure of the lift bridge on Sunday.

The mechanical issue in the south bridge tower was discovered Sunday morning. Engineers were able to lift the bridge to the “up” position at about 1 a.m. Monday to accommodate marine traffic. By keeping the bridge in this position, federal law, which requires a bridge to be accessible to marine traffic at all times, is adhered to.

Engineers have determined the bridge is not safe for routine operation without complicated and extensive repairs. The estimated cost of repairs is upwards of $1 million, and would take more than six weeks to complete.

The Sarah Mildred Long Bridge was already scheduled to close permanently on Nov. 1, to make way for continuing construction of the new Sarah Mildred Long Bridge, which is on schedule to open in September 2017.

Detours are in place for motorists to use alternative routes between Portsmouth and Kittery via the Interstate 95 “High Level” Bridge and the Memorial Bridge (U.S. Route 1).

The Long Bridge will continue to remain open for marine traffic on the Piscataqua River.