The Sonoma Marin Area Rail Transit (SMART) train is projected to start service between San Rafael and Sonoma County Airport north of Santa Rosa in late spring although the exact date will depend upon final federal safety approvals. Initially, rides will be free. The free period will run through the July 4 holiday. SMART will then offer 50 percent discounted rates through the September 4 Labor Day holiday. Regular fares will go into effect on September 5. For more information click here