I used to run along the tracks. The trains were infrequent so not a problem. Great views of the Pacific. I always wondered how long the tracks would last - given the weight of the trains, erosion by the sea, and the kind of substrate they were on.
I was in San Diego a couple weeks ago on business and took a ride over to Oceanside, where I used to live when I was stationed at Camp Pendleton. The Oceanside station was closed for some reason. But I went to the bridge by the marina where Oceanside connects to Pendleton. I used to walk that railroad bridge all the time from my barracks in Area 21 to Oceanside Beach. I remember having to run a couple of times to escape the trains that were coming up behind me. But they built a nice road since then and also a bike trail.