HADLEY — Travel restrictions remain on the Bay Road bridge that runs over the Fort River, as Department of Transportation engineers are working to design fixes for the crossing which is more seriously damaged than previously thought.

The bridge has been reduced to one lane as a safety measure since February, after inspectors found that its timber piles were deteriorating. Since then the state has been using a temporary stoplight to direct traffic as only one direction at a time can use the bridge. That has led to delays on Bay Road.

In addition, the state has imposed a three-ton per vehicle limit on bridge traffic, which has forced trucks to use a detour and has caused the PVTA to reroute buses in that area.

The state originally had hoped to begin and finish work on the bridge during the summer, before college students return for the fall semester.

But a May reevaluation of the bridge revealed that the damage was worse than originally thought, said Hadley Department of Public Works Director Marlo Warner. He said the project was sent back to the drawing board, pushing construction back “a couple months.”

Engineers will now have to redesign their plans, said Ryan Grannan-Doll, Department of Transportation deputy communications director.

The timeline for the repairs to be completed remains unclear, as does its cost, until the design process is finished.

“At this point, there is no timetable for when repairs would begin or be completed,” said Grannan-Doll.

Email Isaac Burke at iburke@umass.edu.