LAWRENCE — The Massachusetts Department of Transportation has announced that the bridge which carries Union Street over the Merrimack River, also known as the Duck Bridge, will be reopened to traffic on Thursday evening with a 3-ton posted weight limit.

The bridge is safe for travel and this weight limit is being implemented to ensure the continued use and reliability of the structure, according to a press release issued by MassDOT.

The state agency is currently developing repair options to restore the load-carrying capacity of the bridge.  

Confining traffic to 3 tons limits a lot of vehicles from using the bridge, including ambulances and school buses. No heavy trucks will be allowed to cross the bridge.

A typical pickup truck weighs around three tons, according to the Pennsylvania Department of Transportation website. Ambulances weigh up to 5 tons and school buses up to 17 tons, fully loaded. 

The bridge is reopening after inspections and analysis from MassDOT engineers and close coordination with key stakeholders. The bridge was struck by an over-height vehicle on Monday.

Someone driving over the bridge noticed the damage on Tuesday, which is when state and local officials decided to shut it down.

It has been closed since 11 a.m. Tuesday, and traffic has been diverted to the Central Bridge or Interstate 495.

As of 2:30 p.m. Thursday, MassDOT and SPS New England Inc., completed a partial repair of the Duck Bridge with parts they were able to obtain, according to a statement from Mayor Dan Rivera.

MassDOT will open the bridge sometime after midnight on Friday.  

The Lawrence Police Department and the Department of Public Works are working with MassDOT to install signage indicating the 3-ton weight limit. The Lawrence Police Department will also have police details on either side of the bridge to enforce this weight limit.

The restriction will remain in place until further notice. MassDOT and SPS New England continue to work to get all the resources and parts needed to complete the permanent repair.