To understand the use and placement of breakaway poles, it is important to understand the concept of “falling area.” Research shows that most errant vehicles striking light poles are traveling at an angle less than 20 degrees from their original path and that light poles fall within one mounting height from the foundation along the direction of vehicle travel. A breakaway pole falls within 2/5 (40 percent) of its mounting height in a direction perpendicular to and away from the lane in which the errant vehicle was traveling (see Figure 6‑3, “Falling area — final position of 50 feet luminaire support.”) Therefore, to prevent knocked down poles from encroaching onto other traffic lanes, breakaway poles should be placed so that they have a falling area of at least 2/5 of the mounting height behind the poles and one mounting height on the side of the pole.

EXAMPLE: In Figure 6‑3, the falling area is calculated as follows:

2/5 × 50 ft. mounting height = 20 ft. falling area