Although light-emitting diodes (LEDs) bring demonstrable benefits to traffic signs and traffic signals, their development has so far been slow. This article shows how LEDs can begin to realise their market potential, by applying precision lensing to bring the latest LED technology into compliance with ITE specifications. Although LEDs are moderately expensive to install at signal-controlled intersections, their costs can be recovered within three or four years through energy savings alone. Maintenance savings are maximised, when all lights at an intersection, including pedestrian signals, are converted to LEDs. Even retrofitting red lights only can halve maintenance costs. Relatively few cities are yet converting traffic lights to LEDs, because trials of older LED technologies have received mixed reviews. New LED technology promises to deliver the unique benefits of LED-based signals, without their past disadvantages. To maximise the efficiency of a LED-based signal head, its light radiation must conform to the pattern specified by the ITE. The only known way to obtain this pattern is by using precision lensing, which should match the LED's dominant wavelength to minimise light loss.
Abstract