Thinking by analogy, I come up with this:

Spock and Bones are seated at a park bench. They are joined by the city planner, a thin, clicking guy who gestures like a puppet hopping on stage.

We’ll have roads, he says. They’ll be 30 feet wide. A yellow line will separate them into lanes and on them vehicles, some tons in weight, will go north and south at 45 miles per hour.

Spock observes, That means the cars passing abreast will be spaced some 6 feet apart at average. It’s a brilliant idea.

Bones says, Are you fucking nuts!