Powering Traffic Signals in an Emergency With Alternative Power Sources

Abstract

Disasters, whether man-made or natural, destroy buildings, structures, lives and natural surroundings. As an example, Hurricane Andrew devastated South Florida with winds up to 140 miles per hour leaving more than 250,000 people homeless and severely damaging at least 85,000 buildings, in addition to traffic signals and other roadway devices. Traveling was hazardous with debris in the roadway, power lines down, traffic signals damaged or not working, and road signs missing. With so many traffic signals not working, normal traffic flow was disrupted and roadways became congested. The importance of maintaining traffic flow in a disaster was evident for effective movement of emergency vehicles and to support recovery efforts. The same effect is realized, but to a smaller degree, during brown-outs, severe storms, accidents and other power outages for whatever the cause. During power outages caused by disasters or other events, there are many traffic signals that are still functional, but not operational due to loss of electrical power. Recent advances in power electronics, lighting and alternative energy sources provide a means of making these functional traffic signals operational during power outages. Updating signal heads with new light emitting diode (LED) lamps will lower the energy consumption by 60 to 80 percent of that of existing incandescent lights. With lower power requirements, renewable energy sources such as photovoltaics, become capable of providing the needed electric power. Redesigning traffic signals to incorporate new low-energy technologies make renewables a more viable source of power. This paper addresses these issues with respect to energy consumption and describes a new design that uses renewables to power these new lighting technologies.