And as Tom Deley said at the interview, the "farm to market" roads were virtually unused. These "back country roads" and State and Federal highways can carry a huge load, because even stalled traffic can get the hell off the road, but its hard to get out of the center lanes of a freeway.
Every hotel has a sign in every room about the evac route.
Why not do the same for every neighborhood, with conputerized projections of load updated every year, and flyers sent to every household to put in their glovebox in every car. On line places to down load yours, just key in your address and print it off.
The farm-to-market roads were blocked -- either had police or "road blocks" up, preventing people from using them. This according to my sister -- who knew the backroads, but was prevented from using them.
The local LEOs directed traffic to the major highways. They didn't give people the choice.
Perhaps the little communities were afraid they would be overrun by the hords of people passing through their towns.