Every day I can look out the window of my office in downtown Austin and watch traffic creep along Interstate 35, half a mile away. The time of day doesn’t seem to matter, nor does the weather: morning or evening, wet or dry, the snarl persists. Part of this is due to the unwieldy design of the downtown exit and entrance ramps, but the main reason is the volume of traffic, much of it commercial. I dread the drive to Dallas, which I last made on the Friday afternoon before the Texas-Oklahoma football game – surely the worst day of...