RELEASE: CONTACT:

IMMEDIATE Erin Gregg 757-925-2584 Sandy Shortridge 757-925-3627

HRO-0302 Jan. 6, 2003

Future looks brighter, cheaper for traffic signals

While stopped at a traffic signal in Hampton Roads, you may notice that things seem a little brighter. That’s because the Virginia Department of Transportation is investing in new technology that not only makes traffic signals brighter and easier to see, but will also save the department thousands of dollars per year in the Hampton Roads region.
Energy efficient light-emitting diodes (LEDs) were installed in traffic signals throughout Hampton Roads and across the state to replace red and green incandescent bulbs. LEDs appear brighter because they fill an entire signal with about 100 diodes, each producing points of light about the size of a pencil eraser. Because the diodes are pointed straight out, they produce equal brightness across the entire surface, making the LED signals seem brighter.
In contrast, traffic signals that use 12-inch diameter bulbs with single incandescent filament use a lot of energy that goes into heat, not light. The filament is heated with the electricity until it glows. This older technology demands a lot of electricity and the bulbs burn out quickly. The incandescent signals also do not spread the light evenly across the surface, but appear to glow in the center of the round signal.
While motorists benefit from brighter bulbs, the bottom line at VDOT benefits from the lower energy costs and less maintenance that LED technology provides. A typical intersection with incandescent bulbs uses about 1800 watts of electricity per month. The LED intersection uses only 240 watts per month, a reduction of 87 percent. LED bulbs have a lifespan of about ten years, which means they have to be replaced less often than incandescent bulbs, which typically last about two years. This results in decreased maintenance costs. VDOT recently changed over red and green signals. An amber-producing diode of sufficient intensity has not been chosen.
Todd Morrison is an LED enthusiast. He manages the traffic signal systems for VDOT in Hampton Roads and is active in the department’s Traffic Signal Field Technicians Roundtable Committee. This group, operating under the nickname “The Knights of Light”, proposed the switch to LED statewide. “This technology is a springboard to other technologies. Once you can run all three traffic signal colors from LED, intersections could run on solar power with utility back up or utility with battery back up. This translates into no loss of traffic signals during a storm or power outages,” says Morrison.
The switch to LED technology is now 100 percent complete in the Hampton Roads district, which includes western Tidewater and the Eastern Shore. Of the 210 total traffic signals maintained by VDOT in the Hampton Roads district, 125 were eligible to convert to LED technology. All red and green bulbs on the more stable 12-inch mast arms were switched to LED. VDOT did not replace bulbs in traffic signals that hang from wires. These signals can turn in the wind and the VDOT Salem District is currently studying LED reflectivity to determine if motorists can easily see the LED lights when the signals hang from wires.