A base plate, which is made of plastic and is intended for supporting a rail for a rail vehicle on a substrate, may include a lower face, and an upper face on which a supporting surface for the rail is formed, a recess, from which a passage leads to the upper face of the base plate, being formed in the lower face of the base plate, the diameter of the recess in a direction transverse to the longitudinal axis of the passage being greater at least in part than the diameter of the passage, so that a stop for an insert piece fitted into the recess is formed on the top surface, assigned to the upper face of the base plate of the recess.