The roundish things are fiberglass enclosures that protect various bits of wiring and other electrical stuff involved with monitoring the state of the railroad. Redwood City, California.

Shot with the Nikon D70s and the 18-70mm f/3.5-4.5 zoom at 70mm, ISO 400, f/9, shutter 1/1000 sec. Exposure, contrast, saturation, levels, and highlights adjustments in Aperture.