In 1980, the City of Portland began a conversion project to change out all existing mercury vapor street lights to high pressure sodium. During the planning and design portion of the project, the City hired a consulting firm to look at our existing system and make recommendations as to light source and fixture configuration. After some on site studies of existing street lighting, it was recommended that all arterial streets of the City of Portland be converted from mercury vapor to high pressure cut-off fixtures, in order to cut down glare in the eyes of drivers. Secondly, it was recommended that, on arterial streets, the City could no longer afford to light “key-hole to key-hole.” It was important to confine the light to the street right-of-way.