The California Department of Transportation has been involved with the
development of LED traffic signal modules for more than a decade. The
recent energy crisis played a key role in speeding up the statewide
conversion from incandescent lights to LEDs.
Caltrans is one of the
largest users of LED traffic signal modules in
the world. Since January 1998, Caltrans has purchased more than 230,000
units for deployment at signalized intersections, ramp meters and
flashing beacons. This number does not include the 8,000 units deployed
prior to 1998 in the Fresno and San Francisco Bay areas of California.
With the current deployments at signalized intersections and ramp
meters, Caltrans has dropped its power demand by 10 megawatts and has
reduced electrical consumption by 71 million kilowatthours per year.
This translates to taxpayer savings of $10 million per year for the
California state highway system alone.
Caltrans operates about 10
percent of the traffic signals in California; therefore, the statewide
energy savings are far greater if all traffic signals are converted.
The availability of LED traffic signal modules led the California
Energy Commission to introduce rules prohibiting the use of
incandescent lamps for traffic signal indications on future traffic
signal installations.
The energy crisis did play a key role in speeding up the statewide
conversion from incandescent lights to LEDs for Caltrans as part of a
statewide effort to relieve pressure on the electrical grid. Prior to
the crisis, the energy and maintenance savings for Caltrans were more
than enough to justify the increased expense of LED modules. The energy
crisis accelerated the rate of deployment by about three to four years.
The rising cost for energy as a result of the crisis simply increased
the economic viability of LED modules.
Energy requirements and prices for LED modules have decreased. Not using LED modules now is an unwise business practice.
Caltrans' involvement in LED traffic signal modules began in 1992, when
the department's Fresno-area electrical crew supervisor, Gerald Tripp,
came across a company with the idea to use LEDs to replace incandescent
lamps in red indications. A large eight-phase intersection in the city of Clovis, CA, (near
Fresno) was the main reason Tripp looked into LED modules. The newly
installed signal in operation at the intersection was too large and
often overloaded the electrical system, causing constant signal
malfunctions.
One option was to redesign the intersection to allow for the traffic
signal, which would have been expensive and would have taken years to
finish. Instead, Tripp initially installed eight LED pedestrian
signals. This helped, but it was not enough. Tripp knew he needed to
find a low-power lamp replacement for the red signals.
After talking with a local supplier, he replaced the red indications
at the intersection with LED modules. The overloading problems
disappeared. The current draw decreased from more than 50 amps to 14
amps. Tripp also found that energy usage for the intersection dropped
significantly-more than anyone expected from simply replacing red
indications. In addition, as one would expect, dollar amounts were
greatly reduced because less energy was used.
Tripp and his supervisor, Jerry McElroy, began a mission to change
traffic signal operations in California. Tripp suggested the idea to
Caltrans management and was rewarded for his ingenuity and innovative
style through the State of California Merit Award Program.
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