Destination sign

A destination sign (North American English), or destination indicator (British English) is a sign mounted on the front, side or rear of a public transport vehicle, such as a bus, tram/streetcar or light rail vehicle, that displays the vehicle's route number and destination, or the route's number and name on transit systems using route names. The main such sign, mounted on the front of the vehicle, usually located above (or at the top of) the windshield, is often called the headsign, most likely from the fact that these signs are located on the front, or head, end of the vehicle. Depending on the type of the sign, it might also display intermediate points on the current route, especially if the route is particularly long and its final terminus by itself is not very helpful in determining where the vehicle is going.

Several different types of technology have been used for destination signs, from simple rigid placards held in place by a frame or clips, to rollsigns, to various types of computerized, electronically controlled signs, such as flip-dot, LCD or LED displays. All of these can still be found in use today, but most transit-vehicle destination signs now in use in North America and Europe are electronic signs. In the USA, the Americans with Disabilities Act of 1990 specifies certain design criteria for transit-vehicle destination signs, such as maximum and minimum character height-to-width ratio and contrast level, to ensure the signs are sufficiently readable to visually impaired persons. In the 2010s, LED signs have replaced flip-dot signs as the most common type of destination sign in new buses and rail transit vehicles.

For many decades, the most common type of multiple-option destination sign was the rollsign (or bus blind, curtain sign, destination blind, or tram scroll): a roll of flexible material with pre-printed route number/letter and destinations (or route name), which is turned by the vehicle operator at the end of the route when reversing direction, either by a hand crank or by holding a switch if the sign mechanism is motorized. These Rollsigns were usually made of linen until Mylar (a type of PET film) became the most common material used for them, in the 1960s/70s. They can also be made of other material, such as Tyvek.

...
Wikipedia