It is thought to have been sited with reference to the Stanegate Roman road, before the building of Hadrian's Wall, to which it is not physically attached. In fact the Vallum ditch unusually goes north of the fort, separating it from the Wall.
The location of this site is thought to have been near the Stanegate Roman road before the building of Hadrian's Wall, but it is not directly linked to the wall.  Furthermore, the Vallum ditch runs north of the fort, creating a separation between it and the wall.