The Texas Department of Transportation (TxDOT) started installing LED signal lamps at signalized intersections around the mid 1990’s. Initially, TxDOT decided to utilize LED signal lamps because they were expected to last longer than incandescent lamps and would not require re-lamping on a yearly basis. Additionally, the LED lamps save in power consumption when compared to incandescent lamps. The installation of LED signal lamps, which use approximately 20 watts or less per indication as compared to incandescent light bulbs at 150 watts, made the installation of UPS/BBU systems more practicable.

Most signalized intersections using LED lamps operate at 400-600 watts, and in a power outage situation, can be powered by four 12-volt batteries for up to four to six hours.

TxDOT has installed UPS/BBU systems at signalized intersections on a limited basis since about 2002. The installation of UPS/BBU systems has become more common and can be found at locations on the state system that are maintained by local governments.

Initially, most of the intersections chosen were at locations that experienced reoccurring power issues. Power issues can damage signal equipment, impair video detection equipment performance, or cause traffic signals to go dark. Some examples of power issues include failures (blackouts), voltage sags and surges, brown outs (under voltages), and over voltages. Power failures require TxDOT maintenance and signal technicians to respond to emergency calls, place the traveling public in less orderly traffic control situations, and result in increased delays, auto emissions, driver frustration, and possibly crashes.

Installing UPS/BBU systems at locations where there have been power issues helps reduce down time and electrical damage to equipment. A signalized intersection that is equipped with UPS/BBU can continue to operate through short-term power losses. Maintaining the green, yellow, and red signal operation through power outages is very beneficial in reducing problems with congestion, substantial delay, and safety. UPS/BBU systems at intersections with preemption for emergency vehicles or railroad crossings are also extremely beneficial.