Right-in/right-out (
RIRO) and
left-in/left-out (
LILO) refer to a type of
three-way road intersection where turning movements of
vehicles are restricted. A RIRO permits only right turns and a LILO permits only left turns. "Right-in" and "left-in" refer to turns from a main road
into an intersection (or a
driveway or
parcel); "right-out" and "left-out" refer to turns
from an intersection (or a driveway or parcel) to a main road. RIRO is typical when vehicles
drive on the right, and LILO is usual where vehicles
drive on the left. This is because minor roads usually connect to the outsides of
two-way roads. However, on a
divided highway, both RIRO and LILO intersections can occur.