IAEEL newsletter 3-4/97
World´s largest order of LED traffic lights
World´s largest order of LED traffic lights
Caltrans, the California Department of Transport, has put out a call for tenders for 50 000 red and orange light-emitting diode (LED) traffic signal lamps, with an option for 24 000 more. Delivery is scheduled for May or June 1998. Battery backup may be the next step.
More and more US cities and states are now putting out larger and larger orders. Henry Arcand at EcoLux (Canada) has sold 33 000 units in California, starting in San Diego, and hopes for other big orders from New York, San Jose, Connecticut, and Minneapolis/St Paul.
Dialite is also doing good business, and Electroctech has sold some 7 500 lamps, with most of them going to West Palm Beach, Florida, and the state of Oregon. "The State of Oregon almost completely converted, and virtually all of their cities have LEDs", says Mike Friedman at Electrotech.
But the planned Caltrans procurement will be the biggest so far. The rationale for the procurement is energy savings. On that basis alone, the pay-back time is 1836 months, depending on the utility kWh price, which ranges from 5.5 cents to 12.5 cents.
"There is no great savings potential in the area of maintenance in California, since every intersection is visited four times a year anyway, in order to check traffic-signal control systems", says Stephen Prey at Caltrans. However, Prey adds that the low power consumption of the LEDs allows the use of a battery backup system. Electrotech offers a battery pack with their LED lamp, so if there is a blackout, the red light will flash for several hours. (In the US, flashing red is similar to a stop sign ‹ first stop, then drive.)
This can save lives during nighttime since some drivers will just pass the non-functioning traffic light without even noticing that there is an intersection. During a major storm, the battery backup will give Caltrans some extra time to fix the problem.
Green lamps are still too expensive for California, but Stephen Prey expects that prices, now 2.5 times higher than for red ones, will fall substantially during 1998 and that solid-state traffic signal heads with a single power source will have been installed by about year 2000. But other states are going for green LEDs right now, such as the state of Vermont, adds Stephen Prey.
Quality issues are very important in California, where temperatures in Death Valley can reach 60°C (140F). High temperature reduces light output, which has to be compensated for either by a different design or by adding more diodes.
Caltrans expects to save about 97 million kWh per year on the retrofit.
Fredrik Lundberg
More info on Caltrans at:
http://www.dot.ca.gov/hq/traffops/elecsys/led/index.htm