The Constitution grants the power to Congress to “establish post roads,” and to regulate “commerce among the states.” As I see this, the authority to set standards for how roads are designed, what signage means, and so forth, are authorities meant to be uniform and useful across the nation. This includes setting uniform rules for traffic signals, speed limits and other rules of the road. Given these rules, states and communities are empowered to build roads, put up signage that conforms to the rules, and enforce them.Local and even state authorities have often exercised their powers without being aware of the national guidelines, of the need for consistency, or the effect on safety. The too-frequent result of this is recognized by the term “speed traps.” Proper legislation at the state level can help subdue this too-frequent temptation to raise community revenue rather than actually improve traffic flow and safety.Motorists have also become a target of overbearing efforts to catch drugs and other illegal activities. Searches and seizures without warrants have begun to acclimatize citizens to embarrassing, unnecessary and unwise submission to improper exercises of government power. Again - state legislation can help steer these deviant activities back to the proper constitutional functions.