Metra says the NATO summit held in Chicago last month cost the commuter rail agency $800,000.
The Chicago Tribune reports that some Metra board members say they're surprised the costs weren't higher.
Metra says the money includes $400,000 in lost passenger revenue for customers who stayed away and money for extra security expenses, including bomb-sniffing dogs and hiring outside security firms.
Metra Chief Financial Officer Thomas Farmer is expected to present the NATO costs at Friday's meeting of the Metra Board.
Metra Board member Jack Schaffer says his agency serves "a great city, and occasionally we have to pay the bill."
According to Metra, the total tab for the NATO summit was about $1 million but the agency expects the federal government to reimburse it about $200,000.