The basic purpose of this report is to study the cost-effectiveness of various luminaries mounting heights and to present a method of evaluating alternative lighting designs that will lead to more economical highway lighting. Initial average horizontal foot candles and uniformity of illumination have been computed for one direction of 2-, 3-, and 4 lane divided highways using overhead mercury luminaries spacing are illustrated. Estimated initial, equivalent annual capital, maintenance and power costs per mile are presented for overhead and bridge rail lighting. Floodlighting of an interchange area with luminaries mounted at 100 feet has been evaluated and costs compared to a conventional system of overhead luminaries mounted at 30 feet. It is concluded that lighting design mounting heights of 40 to 50 feet will provide more economical and effective lighting than the usual 30 foot height.Higher mountain heights will normally provide for safer and more aesthetic lighting designs. The information and techniques shown should enable highway agencies to more accurately evaluate alternate highway lighting system designs, and thus provide a wiser expenditure of public funds. Evaluation of present design techniques, and additional applied research to take advantage of recent lamp development could contribute to more effective, economical, aesthetical and safe highway lighting.
Abstract