Street signs shall be metal on metal posts of the type, design and standard required in the street ordinance or, if there is no street ordinance in effect at the time, than as approved by the approving authority on advise of the Planning Board Engineer. The location of the street signs shall be determined by the engineer but there shall be at least two street signs furnished at each four-way intersection and one street sign at each “T” intersection. All signs shall be installed free of visual obstruction.