How do I change the allowable weight limit on a bridge?

The first step is to determine the allowable load on the bridge. This must be done by a licensed professional engineer. If the engineering review determines the weight limit should be changed, the next steps depend upon who owns and maintains the bridge.
- County
The County Highway Superintendent can post the bridge and should notify the emergency management and sheriff offices of the change. Since this involves a regulatory sign, an order will need to be filed with the County Clerk. - Town
While the Town Highway Superintendent puts up the signs showing the weight limit, the Town Board needs to pass a resolution to change the weight limit. - Cities and Villages
The elected board needs to pass a resolution changing the weight limit. Any signs are placed by the official with responsibility to place any signs. This is typically done by the DPW, but the Mayor is the official who authorizes the signs.
In all cases, signage on the approach to the bridge notifying the public of the change is also required. It is recommended that the posting also be publicized in the local paper and media.
In the case of an emergency, the Highway Superintendent or responsible official for a City or Village may close a road or a bridge, but must notify the municipal clerk and the emergency management/sheriff’s offices of the changes.
Resources
Highway Law, § 234(3):
Vehicle & Traffic Law, § 1660 (Town)
Vehicle & Traffic Law, § 1650 (County)
Vehicle & Traffic Law, § 1640 (Cities and Villages)
NYS Vehicle and Traffic Law
Red Book (Pages 22 & 30)
Association of Towns of the State of New York
Professional Engineering & Land Surveying
New York State Department of Education
Bridge/Culvert, Legal/Liability, Safety - Highway