These Solar Signs Could Make Roads Safer

Interplex Solar is throwing new light on an old product. The Arlington Heights (Ill.) company has developed solar-powered road signs that offer much greater visibility at night. Their glowing outlines are recognizable at as much as 2,000 feet, compared with 1,200 feet for standard reflective signs. Already, highway departments in Illinois and Washington State have begun testing the new signs, while departments in Florida, West Virginia, and Wisconsin have placed orders.Around the edges of the signs and their letters are light-emitting diodes (LEDs), such as those used for readout displays in some calculators. The LEDs are powered by a battery that gets recharged during the day by two solar panels perched atop the sign. The battery stores enough solar energy to power its sign for up to six days, says Robert J. Nellemann, Interplex Solar's managing director. A photocell turns the signs on when dusk falls and off at dawn. The idea was pioneered in Israel by another unit of Interplex Industries Inc. for the sun-powered signs now popping up in Israel and Germany. At $450 each, the solar signs run five times as much as regular versions, so Interplex promotes them mainly for roads and intersections with high accident rates.