PORTSMOUTH, N.H. — It’s unclear exactly when the new Memorial Bridge connecting New Hampshire and Maine will open to traffic, but the celebration date has been set.

Archer Western Contractors has a contractual obligation to complete the bridge connecting Portsmouth to Kittery by Friday, or face $25,000 in fines each day after that. By Thursday afternoon, that looked unlikely.

N.H. Department of Transportation spokeswoman Madeline Vantine said more work needs to be done before the bridge is turned over to the states.

She said the bridge will probably be ready for vehicle traffic before the ribbon-cutting ceremony, which is scheduled for Aug. 15 at 10 a.m.

The celebration will include an appearance by former Portsmouth Mayor Eileen Foley, who was 5 when she cut the ribbon at the original bridge opening on Aug. 17, 1923.

Archer Western and the state originally planned on a July 6 deadline. The transportation department extended that deadline due to two weather events and unanticipated problems with strengthening the piers.

The original bridge over the Piscataqua River cost $2 million to build. It was dedicated as a “Memorial to the Sailors and Soldiers of New Hampshire who participated in the World War 1917-1919.”

The original bridge closed to vehicular traffic in July 2011.