The Mill Plain Road bridge -- closed since April 2010 to make way for a wider span in place of the eight-decade-old structure -- has reopened.

But the new bridge will have to be shut down -- this time only briefly, officials say -- for additional work. Few details of the pending closure were immediately available, but indications are that the work would take about a half-day and probably be done on a Saturday.

"It is on time," Public Works Director Richard White said last week of the 18-month project, despite comments on local blogs complaining about the length of time the bridge was closed and the circuitous detour its closure required.

The bridge had initially been slated to open in time for the start of the new school year, but Tropical Storm Irene delayed both openings.

The $3.9 million project was funded almost entirely with grants from the state and federal government, White said, with the town chipping in $165,000.

White said there were several reasons why so much time was needed to complete the work.

"They had a normal, planned shut down during the winter time," he said, and the times that construction work could actually be done in the water -- the bridge spans the Mill River -- were limited. Utilities also had to be moved, he added, and special care taken not to damage fiber cables and conduits.

Had one lane of the bridge been kept open to traffic while work was being done, White said the project would have taken twice as long. "That's why we went with the complete shutdown."

He said the town didn't hear an inordinate amount of complaints from residents while work proceeded to replace the bridge, built in 1929. "Certainly the residents living south of it, I think they somewhat enjoyed living on a dead-end street," White said, "but there's no doubt about it the detour was long and convoluted, but it was the only reasonable path to get people around the bridge."

The Mill Plain bridge is actually two separate bridges connected by a short section of roadway supported on an island in the middle of the river.

The finished span has a stone facade and timber guardrails backed with steel. The road has been widened by a few feet and a sidewalk added to the bridge's eastern side closer to the park.

Drainage improvements were also made to the north bank of the Mill River and the small island that supports the bridge.