I live in South Carolina just outside of Greenville.  I have a common
driveway shared between myself (homeowner), and my neighbor who lives
in a rented house.  This person also is the apartment manager for the
apartments located across the street.
On many days, at any time of the day, apartment hunters will park at
the head of the driveway while seeking rental information or paying
fees, effectively blocking access from our four lane road and exiting
from our own home.  This practice has caused two 'fender benders' in
the drive, both of which have been construed as our fault.  I can
understand the legalities of it being our fault seeing that we were
doing the backing up both times.
My questions are:
Doesn't this apartment manager's property, rented or not, need to be
zoned for business purposes?
Am I allowed to separate our two drives with a curbstone or some other divider?

The Apartment building needs to be zoned as a multi-family dwelling.
No, you are not allowed to impede access to the driveway by erecting a divider.

You are down to three choices, the way I see it:

1) Mediate
2) Arbitrate
3) Litigate

~~Cynthia