Unless more stringent regulations are provided by other provisions of this chapter, at the intersection of two or more streets no hedge, fence, screening strip or wall higher than 30 inches above curb level, nor any obstruction to vision other than a post not exceeding one foot in diameter, shall be permitted on any lot within the triangular area formed by two intersecting street lines bounding said lot, or the projection of such lines, and by a line connecting a point on each street line located 25 feet from the intersection of the street lines.