By a wide margin, the Los Angeles County Board of Supervisors voted this month to place a 1⁄2 cent sales tax increase on the November ballot. Recent polls show 70% voter support for the measure even before promotional efforts begin. If 2/3 of voters approve the tax, mostly rail but also highways projects in the county will be funded to the tune of $3.5 billion a year indefinitely. That number includes proceeds from two previous tax measures. When all three are combined, two cents of every sales tax dollar collected will be dedicated to transportation in perpetuity.