Originally Posted by wyeast

Minimum of ANSI Class II visibility gear (jacket or vest). Not just for on the bike, but for visiblity if you ever have to dismount to tend to a flat/repair a derailleur, etc. If there are really minimal shoulders (like the right side of the pic - cut into a hill?) for long stretches, I'd consider even carrying a couple of road flares in case you have to tend repairs without being able to pull way off the road.

At least two blinkies on front and back (for redundancy in case batteries or the light dies) Good rear view mirrors. If riding at dusk/night - augment with strong headlights (at least 100 lumens or more) plus as much DOT-spec reflective taping as you can stand putting on your bike. I'd also consider a high-mounted blinky (either helmet-mounted or on a fiberglass flagpole mounted to the bike) to increase your visibility over hill crests / in front of other cars.