Los Angeles to Coachella Valley is one of the California emerging corridors which has been under study for quite awhile (there's been studies on it since at least 1982). They're doing yet another study on it and Riverside County Transportation Commission has a good site on it complete with previous studies back to the 1991 one (though not the 1982 one), interestingly with some proposed extensions to Calexico. Thought I'd drop this in here as a resource for advocacy.