The state Department of Transportation plans to close the Elm Street Bridge Monday to begin a long-awaited bridge replacement project. Town officials said the current bridge over the Jones River will be closed until completion of the new one, forcing drivers to seek alternate routes. The federally funded $3 million project to replace the bridge over the river on a scenic portion of Elm Street is expected to include traffic-calming measures such as a solar-powered speed warning flasher. The project was delayed for a year after federal officials required Town Meeting to vote to take permanent easements on private property along the bridge needed for the project. The town had previously acquired temporary easements.