Skyline Drive is a 11.4 mile lightly trafficked out and back trail located near Corona, California that features a cave and is rated as moderate.
I've looked it up in dictionary, "traffick" means "deal or trade in something illegal", I don't know how it relate to the trail. And what does "out and back" mean here? Does it mean starting a hiking then walking back over the same route?
Thanks for your help！
This is the noun 'traffic' meaning 'movement of people/goods/vehicles etc' used as an adjective to describe that this trail has few hikers/mountain bikers (or a light amount of traffic). A more correct alternative would perhaps be 'frequented', or simply 'quiet'.
As for 'out and back', you are correct that it means that you follow the trail 'out' to your destination. Then, to return, you follow it 'back'. This is in contrast to a 'round trail', which would take you in a 'loop' back to where you started (ie without retracing your steps).
Please note that I found a very similar text to the one you quoted, which claimed that in fact this trail is heavily used.
