PORTLAND — The operators of the Amtrak Downeaster will be working on railroad crossings that will require temporary daytime road closures and detours through mid-August.

Streets that will be affected over the next month include Walton Street, Riverside Street, Congress Street, Read Street, Woodford Street, Forest Avenue and Allen Avenue.

Crews will spend at least two days at each crossing, removing old track and laying new track. Crossings will be closed for 12 hours at a time, will be covered with temporary crossing decks until paving is completed at a later date.

The track work is part of the Downeaster’s $38 million expansion to Brunswick. The project includes the rehabilitation of approximately 30 miles of track, installation of signals and upgrades at 36 crossings.

Seven rail crossings in Portland have already been upgraded in advance of the service expansion, which is slated to begin by fall 2012, according to the Northern New England Passenger Rail Authority, which operates the Downeaster.

The tentative schedule includes July 12 and 14, Riverside Street; July 15, Walton Street; July 19, 20 and 26, Congress Street inbound; July 27, Read Street; July 28, Woodford Street; July 29 and Aug. 1, Forest Avenue; Aug. 2, Read Street; Aug. 3, Woodford Street, and Aug. 6, Allen Avenue.

Up-to-date schedules for the work may be found at 511maine.gov or at AmtrakDowneaster.com/expansion-project.

Randy Billings can be reached at 781-3661 ext. 100 or rbillings@theforecaster.net. Follow him on Twitter: @randybillings.