Bullet trains stay in normal atmospheric pressure at all times. Hyperloop is described as a sealed tube or system of tubes with low air pressure through which a pod may travel substantially free of air resistance or friction. Entering an atmosphere would slow it down immensely so the entire hyper-run must be pressure sealed.
Those pictures showed elevated portions, which would have to hold a vacuum. Any type of damage could make them lose their pressure integrity and possible halt operations.
Underground could work but is California the place to put buried travel modes?