In a taper on a 45 mph roadway, a common rule of thumb for the maximum spacing between channelizing devices (cones) in the taper is that the spacing in feet should be about equal to the speed in mph. Roughly what maximum cone spacing does that give?

Giải thích

Correct: the guidance sets device spacing in a taper at roughly the speed number in feet, so at 45 mph the cones should be spaced no more than about 45 feet apart. Ten feet is far tighter than required (used more for very low speeds or tight work areas). Ninety and 145 feet are much wider than the rule allows and would leave gaps a driver could misread.