Today's circular intersections, known as roundabouts, are a growing trend in the United States. Engineers and urban designers opt for roundabouts when possible to take advantage of their yield-at-entry safety component and their ability to keep ever-increasing traffic on the move.

Carbon monoxide (CO) emissions from operating combustion equipment can trigger state air permitting and annual emission reporting requirements that may drive up costs for owners of landfills and publicly owned treatment works (POTW).