The raider encampment is an unmarked raider camp southeast of the Minuteman Metro Station. You will pass this area if you choose not to fast-travel to Rivet City with James after completing Tranquility Lane; it can be dangerous for low level characters. Take note of the large number of cars when approaching, and beware engaging the raiders from a distance, as the crossfire can easily set one of the many vehicles alight.
The encampment is accessible via the covered bridge to the northeast or through a hole in the fence at the southwestern side. The bridge is held by a single raider, supported by an automated turret controlled by an Average locked terminal at the opposite end. The other side is guarded by a group of patrolling raiders, one of whom is positioned on top of a fortified rubble pile, wielding a missile launcher.