In my usual rushed commute from Barnard College on the west side of Broadway to Columbia just across the street I was stopped by a red illuminated pedestrian signal. I suppose the two hours I had just spent in Environmental Ethics stirred the environmental conscience in me, and I began to think about the electricity consumed from the traffic lights, pedestrian walk signals, and streetlights that adorn every city street corner. A city would not be able to function without such devices, and yet the fact that traffic signals run twenty-four hours a day, seven days a week never occurred to me (the things we take for granted as native New Yorkers). With this as my incentive I decided to do a bit of research on the topic.

According to the PlaNYC 2007 Emissions Data, such traffic signals accounted for 3.7 percent of government greenhouse gas emissions during the Fiscal Year of 2006 (translated as the release of 144,000 metric tons of CO2). With this said, over the 11-year time period from 1995-2006 this particular sector has also seen one of the greatest percentage reductions in CO2 emissions as a result of Citywide installation of light emitting diodes (LED) traffic and pedestrian signals. A report produced by the Traffic Engineering Division Department of Public Works in the City of Little Rock demonstrates that some of the main advantages to LED signals include their lower power consumption (10-23 Watts) and their long life existence which can be as high as 7-10 years. This is compared to incandescent light bulbs that consume up to 135 Watts. Additional benefits include reduction of equipment failure since an LED signal is composed of several dozen LEDs unlike the incandescent bulb that contains only one filament. Intersection safety is enhanced since LED signals are brighter compared to incandescent traffic signals. While their initial cost might be significantly higher than the incandescent price of $2.75/bulb, it seems as though their long life span will lower replacement costs, they provide an eco-friendly alternative to the inefficient incandescent bulbs.

Yet, an interesting article in the Tech Generation Daily foreshadows the potential for the impending doom of LED traffic signals. The author suggests that as more states are replacing incandescent traffic lights with LEDs, many northern regions are discovering a potentially serious flaw that is believed to have caused at least one death in a fatal car crash in Oswego, Illinois. Authorities are partially blaming lower power consumptions and lower heat emissions within LED-based traffic lights for the accident. They argue that the LED traffic lights are ineffective in melting snow and ice, resulting in reduced visibility of snow-covered traffic lights.

LED traffic signals might make progress in the mitigation of greenhouse gas emissions; however as it turns out the costs might not outweigh their benefits.