Alternatives for Energy Conservation in Roadway Lighting

About the report:

From a review of some of the possible methods of conserving energy in the operation of roadway lighting, with due consideration being given to traffic operations and safety under the current energy scenario, it was concluded that the most favorable conservation measure would be to replace the existing mercury vapor luminaires with the more energy-efficient high pressure sodium (HPS) luminaires. Replacement of the existing mercury vapor lighting systems could lead to a savings of up to 50% of the power currently being consumed. Following a discussion of this conclusion by the Department of Highways and Transportation's Special Roadway Lighting Advisory Committee, it was decided to inventory all of the interstate lighting currently in-operation and to estimate the savings that could be achieved through conversion to HPS luminaires. The results of the inventory and analysis indicated that the conversion of 4,752 interstate system luminaires could yield a present worth savings to the Department of $1.2 million over the average remaining service life of the various installations, assuming the use of the available 90% federal funding. It was further determined that it would take only 7 1/2 months for the Department to recoup its 10% investment and 9.9 years to break even on the total investment. Based on these data, the recommendation to convert all the interstate mercury vapor lighting to the HPS type was approved by management. Currently, approximately 75% of the original inventory is nearing the contract stage for conversion. Other alternatives for conserving energy in existing roadway lighting systems are discussed and placed in order of preference in the report.

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