Our LED streetlights make colors look bright and more "true' to the natural color. Trees look green instead of brown; a blue car looks blue instead of gray. Because of this improved color rendition, everything appears brighter and sharper under the new streetlights, even when the amount of light is less than the old lights.

The “color temperature” (warm-cool) of the streetlights is 4000K, which is in the middle of the warm-cool range.  This color temperature closely matches moonlight. This color temperature of the new lights is the same or “warmer” than the quarter-of-a-million LED streetlights that have been or are being installed in Boston, New York, Los Angeles, Oakland and San Francisco. The color of the new streetlights is the “warmest” typically available for LED streetlights.

The City has selected a Cree LEDway Streetlight, 40LED, 80LED and 120LED. The new lights will reduce unwanted spill light into homes and properties.

The new street lighting system will consume about 25% of the energy of the existing streetlights, saving the City an estimated $500,000 per year in electricity costs, and allowing us to meet the "carbon footprint" reduction goals that we have set for ourselves.

A wireless control system has been installed. This allows dimming of the streetlights. When a new streetlight is installed, it will be much brighter than normal until it communicates with the dimming system. Most of the streetlights are already under the control of the dimming system which turns lights on to only 70% of their potential brightness, and later in the evening, dims them even further to about 35% of their brightness. By the time most of us are going to bed, the streetlights will be dimmed to about a third of their current brightness. This dimming system is unique among mid- to large-size cities in the U.S. and reflects the sophisticated approach Cambridge has taken.

Drawing from a pool of emerging and ongoing research into visibility, safety, and the effects of lighting on the environment, a system of street classifications was developed to determine appropriate light levels for various types of streets, from the smallest tree-lined residential street to the busiest urban intersection. Using detailed information from the City’s Geographic Information Systems (GIS) database, as well as on-site evaluations, streets were evaluated for width, light pole spacing, and vehicular and pedestrian activity.

Each street throughout the entire City was examined in person by a member of the project team. Test installations were conducted on Inman Street and Rindge Avenue in 2010, and on small sections of several others streets in 2013.

After comprehensive analysis, the streets were assigned to a range of categories, addressing lighting requirements for both roadways and sidewalks, and limiting glare and light trespass. These standards are in accordance with the most stringent established guidelines (used by the Federal Highway Administration, MassDOT and the Illuminating Engineering Society) while still aligning with the unique characteristics of Cambridge and its diverse neighborhoods.

LED streetlights will provide more consistent and appropriate illumination throughout the City. Improved color and uniformity, reduced glare, and greatly improved color rendition will increase visibility, security, and safety on our streets and sidewalks. Unwanted “spill light” into homes and onto properties will be reduced by specialized optical assemblies. A state-of-the-art wireless control and monitoring system will allow fine-tuning of light output, enhanced energy conservation, and energy usage tracking capabilities.

The City has replaced about 7,000 lights (4,900 on street, 2,100 specialty and park fixtures) with energy-efficient LED fixtures.