Railroad signals serve much like traffic lights, telling locomotive engineers when to proceed, proceed with caution, or stop. Colored-light railroad signals of this kind were introduced around the turn of the last century and remain in use on railroads such as CSX, Norfolk Southern, and Amtrak. Because this type of signal has no reflectors in its lights, a locomotive headlight will not make the lights appear lit when they are not. One such signal, made by the Union Switch and Signal Company of Pittsburgh, Pennsylvania, sometime in the 1930s, was used on the Pennsylvania Railroad's New York and Long Branch Railroad in New Jersey. Tall switch stands were used to change track positions, allowing trains to switch tracks, and were used mainly along mainlines rather than in yards. Their metal flag, called a target, showed engineers from a distance which way the switch was set, and some had lanterns on top for nighttime use. In earlier years, a dispatcher controlled signals and switchstands from a signal tower beside the tracks; today, the dispatcher works at a computer in a dispatch center.