The problem-plagued reconstruction of the North Avenue bridge has hit another bump in the road.

Work on the span over the Merritt Parkway, where the state’s lagging project threatened to pose a major traffic bottleneck for school buses in late August as the new academic year was about to start, has now been suspended. That’s because contractors have to shore up damage caused by “numerous impacts from over-height vehicles,” a state Department of Transportation spokesman said.

The latest setback to the construction schedule is expected to push back completion at least a month past October, the date that state and town officials agreed on after the initial mid-August date could not be met.

“Due to the numerous impacts from over-height vehicles, the lower portion of the temporary support had to be removed due to damage,” Judd Everhart, the Department of Transportation spokesman, said Wednesday. “The contractor is redesigning the support system to give additional clearance to vehicles.

“At this time, work has temporarily stopped until this issue is resolved,” he added.

Meanwhile, traffic lights have been installed at either end of the bridge to control traffic — alternating in opposing directions — across the single lane that remains open.

“We have been aware of the difficulty that the DOT has been having with illegal over-height vehicles traveling on the Merritt Parkway and then hitting the support structure,” First Selectman Jim Marpe said when questioned Wednesday about the latest problem with the project.

“I’m extremely disappointed that the work will be extended,” he said, “but it is fortunate that at the insistence of the selectman’s office, the DOT opened one reversible lane of traffic on the bridge in time for the opening of school. While not an ideal situation, the arrangement will continue to provide traffic flow on North Avenue.”

Marpe said town officials “have been waiting for the DOT to work through their technical discussions to develop and announce a solution.

“It’s unfortunate that a safety issue on the North Avenue bridge project has created an additional delay,” he said, but “obviously, the safety of the workers on the bridge is the paramount concern.”