Light-emitting diodes (LEDs) are rapidly taking their place as the pre-eminent efficient lighting source. Many cities have invested in LEDs to light their streets. One such city is Detroit.


Two years ago, the city declared bankruptcy. One of the consequences of the city’s financial distress was the decline and neglect in its streetlight maintenance. The city estimates that as many as half were not in reliable operating condition.


Last year, the city launched a project to switch out almost all of its 88,000 existing street lights, most of which were high-pressure sodium (HPS). 


Since the launch of its conversion to LEDs, improvements are already apparent. In October, the U.S. Department of Energy (DOE) released a report, “Restoring Detroit’s Street Lighting System,” that reaches a number of positive conclusions about the project, which is still underway.


According to the report, the new LED system in Detroit will cut energy use by 60 percent, saving about 46 million kilowatt-hours per year, worth about $2.9 million. It also projects that the resulting savings will more than offset the incremental expenditure for the LEDs, with a payback of less than 2½ years from energy savings alone. Reduced maintenance costs will save the city even more.


The report adds that the new lighting system will help fight crime by improving reliability and safety, improving resistance to vandalism, and decreasing opportunities for theft.


Not all results are positive. According to the DOE report, while the new system generally delivers higher quality illumination than the previous system, the quality of illumination in some residential neighborhoods has been slightly compromised due to the removal of some poles and luminaires. As a result, the remaining lights must illuminate greater distances. Due to budget constraints and population declines in some neighborhoods, the city reduced the total number of streetlights from 88,000 to 65,000.