The old granite block culvert that carries the Miles River under Bridge Street is being replaced with a precast concrete box culvert, starting Monday, July 11.
The work will mean that the bridge will be down to one lane during the project, which is expected to last through the end of September. Temporary traffic lights will control traffic during the project by alternating traffic from both directions.
The Federal Emergency Management Agency is paying for about 75 percent of the project costs from a grant, according to DPW Director Bill Redford.
The work will involve blocking the river with a coffer dam and the flow will be diverted through temporary pipes while the culvert work is performed, Redford said.