I've worked on the Santa Ana River Interceptor (SARI line) project over the last year. As I recall, no part of that job involved crossing the rails at the crossing near the Green River golf club house. I'd bet the driver got lost. The tie in location is just about 1/4 mile towards Fullerton from xing and on the southerly side of rails. Tie in is at concrete slab.
The second photo shows lead loco 100 yards or so before crossing. My location was between tie in and xing. Many trains traversed these rails during my work days. Got lots of photos since, how fast can they connect up a 54" diameter pipe?