I know, right?@ 6:24... Damn it @TonyR
He barely tapped it and over it went!
The traffic signal pole was installed on what's known as a ballast base that was used many, MANY years ago when the ballast for the mercury vapor street light could be located there and then wires run up to the luminaire on the tip of the upper mast arm. They made them also out of aluminum for aluminum street light poles with NO long mast arms for traffic signals, it was strictly for street lights. The long arm of the signal mast arm acts like a lever and if you install the wrong type of ballast base OR not have enough of the foundation bolt threads showing above the 4 nuts, it can happen.
Bottom line: poor job by someone installing the pole, it should have taken that bump, even to the point of denting the pole. Some moron may have used expanding anchors in the sidewalk and mounted it that way.