Just south of Victorville, California, the Mojave River cuts through the hills. The Atchison Topeka & Santa Fe Railway took advantage of this natural river engineering to get their rails through as well, and when this line was double tracked years later, a "natural crossover" was constructed at Frost. This allowed trains to position themselves without block any opposing traffic, as nearby Cajon Pass featured left-hand running to take advantage of the newer, gentler grades for uphill running, and the steeper, original grade for westbound, downhill, operations. On a very pleasant spring morning, BNSF Railway train Q-ALTLAC1-12 crosses over a Union Pacific eastbound train (UP has trackage rights here) as it ticks off the last hundred miles (or so) from Alliance TX to Los Angeles. (Victorville, California – May 15, 2020)
