Traffic Signal Light Emitting Diode (LED) Implementation Process
Whether you are a visitor to Grand Blanc or a resident, you may soon notice some differences in the City’s traffic signal operations. Most traffic lights will be brighter and easier to view than before, even when the sun is shining on them. That's because the City of Grand Blanc has received a grant to install Light Emitting Diode (LED) traffic lights in place of pre-existing incandescent lights.
Compared to incandescent traffic lights, LEDs have greater light intensity and are designed to absorb, not reflect, most sunlight that enters the lenses. Also, LED lights are more visible, last much longer, and use much less energy.
Various forms of LEDs have been in use in the U.S. for many years. Most of the tiny red and green indicator lights you notice on your appliances, radios, and other digital visual effects are LEDs. However, in the last decade, their use has expanded to many other areas, including use in automotive tail lights and turns signals, as well as traffic signals.
Research: Timing is Everything
For several years, the City of Grand Blanc monitored the development of LEDs as an alternative means for street signal operation. Since LEDs require much less energy to operate, they cost less to operate.
Until recently, LED traffic light implementation was not an economically sound investment due to operations and reliability concerns as well as high costs for materials. However, technology has changed significantly in recent years, making LED light implementation an economical possibility for the City. However, technology has changed significantly in recent years, making LED light implementation an economical possibility for the City.
The City reviews signal operations annually and determines necessary upgrades Grand Blanc's signal system. During one of these reviews, it was determined to many of the City traffic signal components (see photos at right) were scheduled for upgrade or replacement. To save on installation costs, LED traffic light implementation was considered as part of the traffic signal upgrade or replacement program.
The City of Grand Blanc also consulted with several Michigan municipalities that use LED traffic lights and determined that these lights have become very reliable considering the various climate changes in the state.
Efficiency of LED vs. Incandescent Lights
The basic mechanics of how LEDs create light are very different than that of incandescent lights used in traditional traffic signal operations. As described below, efficiency can be measured by the amount of useable energy.
Efficiency of Incandescent Lights
A standard light bulb relies upon electrically heating an element to emit visible light. Light emission requires a significant amount of power to occur. This process is called incandescence. Approximately 2% of the emitted energy from an incandescent source is useable visible light with the remaining 98% being wasted heat. Incandescent bulbs are likely to burn out frequently and require replacement each year.
Efficiency of LED Lights
In contrast, LEDs are much more efficient and last longer. That’s because LEDs emit light by using an electrical current to create a bond between positive and negative charges. This process is called electroluminescence. This is much more efficient, as nearly 100% of the emitted energy from an LED source is useable visible light. Due to varying energy use, LED traffic lights are known to last approximately 10 times longer than incandescent traffic lights. LED traffic lights usually have a replacement warranty of five years, but are expected to last longer.
Standard incandescent light is diffused light, which basically means the light spreads out when in operation. Standard LEDs produce direct light but can be manipulated to diffuse, or spread out, so the light is visible at different angles. This can be controlled by altering the size, shape and location of some of the LED components that make up an LED traffic light.
Reduction in Energy Costs
Through a coordinated effort with Consumers Energy, a system has been developed to make sure that once the LED work at each signalized intersection is completed, Consumers Energy will be immediately notified. Once notified, Consumers Energy will place the information in their system and reflect the changes on their next billing cycle to the City of Grand Blanc.
To Find Out More...
For more information regarding LED lights, check the following websites:
ENERLEDS Traffic Lights - http://enerleds.com
Olympus Microscopy Resource Center - http://olympusmicro.com
Consortium for Energy Efficiency - http://www.cee1.org
Institute of Transportation Engineers - www.ite.org