If memory serves me right, It was on a road going into a campground. The campground was also enclosed in a high electric fence, but it was 8 years ago, and I am getting older
Cattle guards are a common thing in Oregon, especially the eastern half of the state. There are millions of acres of public land that are under "cattle allotments" (rented to the ranchers for grazing). I don't remember seeing any cattle guards on the coast route.