RALEIGH — North Carolina’s traffic congestion could double in the next couple of decades, with Charlotte drivers facing the same types of delays Chicago drivers face now. That was the conclusion of a 2007 John Locke Foundation report. It recommended $12 billion of spending to clear North Carolina’s congested urban roads and prepare for future traffic growth. Many traffic problems outlined three years ago continue to cause concerns today. Randal O’Toole, senior fellow with the Cato Institute, recently tackled the issue from a national perspective in the book Gridlock: Why We’re Stuck in Traffic and What to Do About It....