IF THERE WERE INFIRMARIES for infrastructure, American roadways would be laid up in the intensive care unit. So suggests the American Society of Civil Engineers , which gave U.S. highways a ‘D’ grade in its 2017Infrastructure Report Card. Despite the dire prognosis, things were looking up as recently as last summer thanks to a handful of “smart highway” projects underway across the nation, the most ambitious of which was Colorado’s RoadX program.