I'm not a big fan of the rail. But the one idea I do support is that it is elevated. I watched the San Diego trolley evolve. Every entrance to a major business along the coast from San Ysidro to Mission Hills became a traffic nightmare because of the crossing arms impeding traffic. If police activity was involved the crossing arms could be down for some time. Traffic to the military bases and major interstates on ramps were  jammed. Berentania and King Street would become nightmares. Keep it elevated.