Depending on whom you talk to, the Trans Texas Corridor is a daring futuristic plan, the state's most ambitious ever, or it's a money machine and a destructive land grab. But for now, most of all, it's an enigma. There are no construction contracts for any of the 4,000 miles of car and truck lanes, freight and passenger rail lines and utility lines that are supposed to crisscross Texas by midcentury, just a $3.5 million deal with a private consortium to develop plans for the leg paralleling Interstate 35. And nobody knows just where the routes would go, though any...