The topic isn't the comfort of your individual automobile; the topic is how to move thousands of commuters every day, into and out of Denver.  The Valley Highway is packed, I-25 stretching southward to Castle Rock and Colorado Springs comes to a stand-still in the middle of nowhere even when there is no accident or road construction to impede traffic.  U.S. 36, the old Denver-Boulder Tpk., is at capacity during rush hours now.  For mass transit, that is, for PUBLIC transportation, the use of tax dollars is the only sensible way to create a commuter rail network.