Arlington is deploying the latest state-of-the-art, intelligent light-emitting diode (LED) street light and signal technology throughout the County to modernize the network, reduce overall costs and minimize the environmental impact. The County maintains approximately 6,200 street lights. Almost all of these street lights were based on outdated, inefficient high-pressure sodium technology which is expensive to operate.
The County began converting traffic signals in Arlington to LED technology in the mid-2000s. In 2010, the County began upgrading street lights along both residential streets and major corridors. As of September 2013, approximately 4,800 (77.4%) have been converted to LEDs.
Through 2013, the next conversion of existing street lights to LEDs in residential areas will occur in the following neighborhoods. Click on the name to view area map:
- The retrofitting/conversion process takes up to two weeks for each street.
- During the conversion installation process, street lights will remain off, and crews will work to minimize the traffic impact in the area.
- Conversion includes testing of the initial operation of the newly retrofitted lights and the implementation of the remote dimming capability. Each light must be individually programmed for dimming purposes.
LED Street Light Program Goals
- To modernize the network, reduce costs, minimize environmental impact, and improve safety and visibility for vehicular and pedestrian traffic on the County roadways.
- The converted energy-efficient street lights support Arlington’s environmental and energy goals.
- The project meets or exceeds the International Dark Sky Association standards (they do not produce upward light and minimize the backlight above a 45 degree angle), thus reducing light pollution and minimizing interference with wildlife.
- The LED lights do not contain mercury, lead, and harmful UV and IR light, which were found in older light bulbs.
- The system’s wireless capability will allow staff to program the lights to automatically gradually dim according to the time of day and the surrounding area (commercial or residential). Additional details are below.
- The County anticipates an energy cost savings of nearly 75% annually and a further reduction in greenhouse gas emissions. This program is another way that Arlington County is meeting its energy savings goals through carbon reduction.
- LED lights have many features that make them ideal for use in Arlington’s street lights and signals.
- LED street lights have longer usable life – 25+ years (as opposed to three years for older bulbs)- and use approximately 75% less power making them less expensive to maintain.
- The LED street lights selected by the County have a seven year warranty. The pay back on the investment is approximately six years, before the end of the warranty.
- The lights produce uniform distribution and dispersion creating safer roadways and sidewalks for all users.
Brightness of LEDs
- LED street lights are a “whiter” light than the perceived “yellow” light of high-pressure sodium lights (HPS).
- The LEDs produce light very close to the color of sunlight, almost pure white, which is the most effective color for seeing during the night.
- With the passage of time the HPS lights produced less usable light due to discoloration and baking of dust on the globes – with time their usability diminished. LEDs do not degrade over time, and do not result in discoloration of the globes.
- LED street lights actually put out less light. The HPS lights put out 9,600 lumens as compared to LEDs, which put out 4,600 lumens. The old HPS lights produce very little usable light on the streets and sidewalks for the energy they consume.
- All LEDs in residential areas will be connected to a smart technology that dims the lights for residential streets as the activities on the roadway lessen. The dimming technology works on dusk to dawn cycle: light comes on at full 4,600 lumens for the first 20 minutes or so, and then drops to approximately 50% (2,225+/- lumens) until about 11:00 p.m., when it drops to approximately 25% (1,050+/- lumens) until dawn. The timing of the dimming program is set to balance concerns for brightness with national standards for safe lighting of sidewalks and streets for bicycles, pedestrians, and vehicles.
- In order to reduce the brightness of the LEDs on neighborhood streets, the County has also begun installing “eyebrows”, which shield some of the light output, on the side of the lights adjacent to homes at the time of retrofit. In addition to the dimming, these eyebrows should mitigate concerns for the brightness of the LEDs.
For questions regarding Arlington’s street lights and signals, contact Santosh Neupane, Street Light Engineer, via email or 703-228-0778.