Metro Ticket

Metro tickets are miscelaneous items in Fallout 3.

Characteristics
Metro tickets are requested at any metro station in the Capital Wasteland that still have active protectrons. Having a ticket can prevent one of these protectron from turning hostile. These Protectrons are inactive by default but can be activated if you can hack the nearby terminal.

Locations
Metro tickets aren't in abundance around the wasteland except in metro stations, but if you have Broken Steel, metro tickets will be scattered everywhere on desks in the Olney Powerworks. As many as 50 can be recovered. While travelling through Old Olney Powerworks, there is a desk which has a stack of metro tickets built in a traditional triangular card stack.

Some Feral Ghouls in the Metro tunnels carry metro tickets. This implies that those are passengers who encountered Nuclear emissions while riding a train.

Bugs

 * Sometimes when the Protectron scans you and you do have a ticket, it won't take it and, in turn, attack you.