In a suburb just northwest of D.C., cars, pedestrians and bicyclists navigated a major intersection whose recent redesign, officials say, is saving lives. The crossroad features raised islands at each corner, physically separating vehicles from bicycle lanes that line each street, as well as marked crosswalks. Drivers are forced to slow down and turn at a tighter angle, giving them, and pedestrians in their path, more time to react. Some residents welcomed the changes. Others pushed back. Shortly after the redesign, a driver pulled up next to county safety specialist Matthew Johnson and rolled down her window. "This is the dumbest interchange I've ever seen. It's so hard to drive through, I had to go so slow," Johnson, standing in the intersection in an orange vest, recalled her telling him. "And I was like, ‘That's the point," he said. “‘The whole point of this was to make you drive more slowly so that you'll yield to a pedestrian.’" This neighborhood could have been anywhere on...