Chris Christie sure has a knack. The New Jersey Governor keeps shocking the political class on behalf of taxpayers, most recently by terminating work on a new passenger-train tunnel that was supposed to run under the Hudson River into Manhattan.

Mr. Christie lowered the boom last week, citing cost overruns from a federal audit that had revised the tunnel price to as much as $14 billion, up from $8.7 billion only two years ago. "The only prudent move is to end this project," he said. "I can't put...