Education for all drivers, should be taught that horses and riders have the right of way. There are laws, which state that if a rider ask a driver to stop or slow down, it should be taught to all drivers.
My friend, who makes a living leading trail rides, sometimes rides in the dusk, or on moonlight rides. Even though there is mostly trails and feilds to go in, sometimes they go on the road for short periods of time. She has reflective strips (bought from Curves) on the bottom of her stirrups, and reflective bandages around the horses tail. She was never 'almost-hit'. I have a bright orange vest that I wear when I am out on the road after dark, when I remember to bring it along!