A street light, light pole, lamppost, street lamp, light standard or lamp standard is a raised source of light on the edge of a road or path. Similar lights may be found on a railway platform. Many lamps have light-sensitive photocells that activate the lamp automatically when needed, at times when there is little to no ambient light, such as at dusk, dawn, or at the onset of dark weather conditions. This function in older lighting systems could be performed with the aid of a solar dial. Many street light systems are being connected underground instead of wiring from one utility post to another. Street lights are an important source of public security lighting intended to reduce crime.