Sight easements shall be provided at all intersections, and shall include the area on each street corner that is bounded by the right-of-way lines and the line which connects the two sight or "connecting points" located on each of the center lines of the intersecting streets. The first sight point shall be located on the center line of the side street, 20 feet from the pavement edge of the through street, measured perpendicular to the through street. The second sight point shall be located on the center line of the through street, at a distance, measured along the street center line, from the intersection of the street center lines as indicated in the following schedule: