Rivet City Security Force

Led by Chief Harkness, Rivet City Security serve as the security/police force protecting Rivet City. They guard key points within the City, such as the bridge into the city and the Market, as well as patrolling the corridors of the ship-city for "troublemakers".

They seem to have a rather laid-back attitude towards their job, informing the player that "If someone steals something from you, take it back. If someone shoots at you, shoot back." and stating that they will only intervene against crimes they personally witness. They do, however, become hostile towards and hunt down anyone seen commiting acts of violence against Rivet City inhabitants (namely, the player character if they go on a rampage).

Rivet City Security wear a Rivet City Security Uniform (an inferior variant of Combat Armor but excellent to repair reilly's armor with) and a Rivet City Security Helmet (a combat helmet with a plexiglas face shield in front). They wield 10mm SMGs. In terms of durability, they're about on par with mid-level Raiders, and go down after 2 or 3 hunting rifle headshots.

Rivet City Security Guards carry a "hangar key" to the Marketplace.

There are an unlimited number of Rivet City Security, as new members will gradually respawn to replace any that you kill. This makes them a decent source of repair parts for Combat Armor and the 10mm SMG, although killing them for their equipment will of course put you at odds with Rivet City.

Broken Steel
In Broken Steel, Rivet City Security can be seen acting as guards for the Water Caravans transporting Aqua Pura from Project Purity to the rest of the Capital Wasteland. Each Water Caravan is usually accompanied by 2 Rivet City Security guards armed with 10mm SMGs. If spoken to, these guards often express concern over Water Caravan duty, stating that it is a suicide mission. Indeed, these caravans often fall victim to attacks by Super Mutants, Enclave, critters, and the Wasteland's various other hostile inhabitants.

Water Caravans also sometimes have Brotherhood of Steel Paladins instead of Rivet City Security as guards. These heavier-armed caravans tend to perform better when ambushed by hostiles.

Appearances
appear only in Fallout 3.