“A blue flag by day and a blue light by night conspicuously displayed at one or both ends of an engine, car, or train, indicates that workmen are under or about it; when thus protected it must not be coupled to or moved. Workmen will display the blue signals and the same workmen are alone authorized to remove them. Other cars must not be placed on the same tracks so as to intercept the view of the blue signals, without first notifying the workmen.”

Rule 38, Book of Rules, The Washington Terminal Company, effective 12:01 am, October 1, 1925.

DCNRHS (The National Railway Historical Society, Washington, D.C. Chapter, Inc.) is a non-profit 501(c) organization founded in the District of Columbia in 1944.  Gifts are tax-deductible to the maximum extent permitted under the Internal Revenue Code.