The workers were performing track inspections on outbound tracks between Potomac Yard and King Street when a broken down train resulted in Metro re-routing trains. Unfortunately, Metro did not bother to tell the track inspectors. This was particularly dangerous as Metro employee, John Moore was killed nearby in a similar incident more than a year ago. See http://www.maryland-law.com/blog/metro-employees-death-brings-to-close-tragic-summer.cfm
Fortunately, a track spotter saw what Metro had not deigned to tell its workers. Think Metro will get the message this time?