Split-flap display

Flap display as departure board in Hannover railway station, Germany
A flap display in Taipei Railway Station, Taiwan
Section of a split-flap display board at Frankfurt (Main) Hauptbahnhof (taken April 2005).
Schematic of a split-flap display in a digital clock display
Flap departure board at Gare du Nord (Paris)
Enlarged inner workings of a split-flap clock
The main departure board "Signaltron" produced by "Pragotron", at the vestibule of Praha-Smíchov station, Czech Republic
Split-flap display with the name of the end station on the tram Tatra KT8D5 in Prague, Czech Republic

A split-flap display, or sometimes simply flap display, is an electromechanical display device that presents changeable alphanumeric text, and occasionally fixed graphics.

Often used as a public transport timetable in airports or railway stations, as such they are often called Solari boards after display manufacturer Solari di Udine, of Udine, Italy, or in Central European countries they are called Pragotron after the Czech manufacturer.

Split-flap displays were once commonly used at consumer scale in devices known as flip clocks.


Each character position or graphic position has a collection of flaps on which the characters or graphics are painted or silkscreened. These flaps are precisely rotated to show the desired character or graphic. These displays are often found in railway stations and airports, where they serve as flight information display system and typically display departure or arrival information, although digital equivalents are far more common now.

Sometimes the flaps are large and display whole words, and in other installations there are several smaller flaps, each displaying a single character. The former method is limited to the words it can display on the flaps, while the latter system is not, and output messages can be changed without the need for the addition or replacement of flaps, although images cannot. In the example image on the right, the destinations in the centre of the picture are split into characters, while the messages left and right of these occupy one flap each.

During a power loss or disruption the display will freeze. At first this may be an advantage because the information is still correct. When the information becomes outdated it might be worse than no information.

Flip-dot displays and LED display boards may be used instead of split-flap displays in most applications. Their output can be varied more easily (by reprogramming instead of replacement of physical parts in the case of graphics) but they suffer from lower readability. They also can refresh more quickly, as a split-flap display often must cycle through many states.

Advantages to these displays include:

Many game shows of the 1970s used this type of display for the contestant podium scoreboards. Usually, the flip was left-to-right on a vertical axis, although up/down on a horizontal axis was not completely unknown. Early seasons of the game show Family Feud used a split flap display as part of the game board (subsequent seasons used more modern digital displays, and eventually simply used a large digital flat screen monitor). The game board on the Nickelodeon game show Make the Grade was a 7x7 split-flap display, used to display subjects and wild cards, as well as tracking contestants' progress. The television game show Chain Reaction on GSN features computer-simulated split-flap displays to display the various words in a chain.

In Italy, split-flap displays have also been occasionally used as destination signs for transit vehicles, there was also a brief vogue for them in the United Kingdom in the mid 1980s.[2]

Operational boards in transport terminals

This list is incomplete; you can help by expanding it.

The boards are currently in use at the following stations:




Most of the major railway stations in France still have one or several split-flap displays, including Paris Gare du Nord and Gare de Montparnasse, as well as Strasbourg, Nantes and Toulouse-Matabiau stations.


Frankfurt Airport, gate A check-in area.


In Greece, the usage of these displays is still widespread. Most airports and train stations have one, most notably the Athens International Airport, which has two enormous displays of this kind. Bus stops, tram stops as well as the station of the Athens Metro and the Proastiakos Commuter Rail System of Athens use electronic displays.







Sri Lanka



United States

Boards no longer in operation

Solari Board at London Liverpool Street (now removed).

Stations previously equipped with these boards included, amongst others:



Hong Kong




United Kingdom

United States



The Netherlands

Non-informational uses

The aesthetic appeal of the displays are such that they have also seen use in purely artistic forms, such as in Pedestrian Drama, contemporary artwork using this display technology, and art by Juan Fontanive, who has used the mechanism extensively since 2005.

The album cover for The Enemy's album We'll Live and Die in These Towns is based on the Solari design seen at British railway stations.



  1. Mac Daniel (2006-04-06). "Nostalgia for noise at South Station - The Boston Globe". Boston.com. Boston Globe Media Partners, LLC. Retrieved 2014-04-30.
  2. "Eastern National Olympian Coach".
  3. Ruedi Baumann (2015-10-19). "Sie ist weg". Retrieved 2015-10-19.
  4. Mark Dent (2016-08-25). "Amtrak to replace 30th Street Station's iconic flipping departures sign". Retrieved 2016-08-29.
  5. https://web.archive.org/web/20110707222928/http://www.beloblog.com/ProJo_Blogs/newsblog/archives/amtrak.jpg. Archived from the original on July 7, 2011. Retrieved February 12, 2011. Missing or empty |title= (help)
  6. Soar, Matt. "Solari Displays and Flight YMX". Solari Displays and Flight YMX. Retrieved 7 July 2016.
  7. https://web.archive.org/web/20110717195416/http://www.vicinitee.com/liverpoolstreetlive/index.cfm. Archived from the original on July 17, 2011. Retrieved February 12, 2011. Missing or empty |title= (help)
  8. Network SouthEast Railway Society. "BRIGHTON 'SOLARI' TRAIN INDICATOR BOARD SAVED BY NSERS". Retrieved 2013-11-04.
  9. Smith, Robert A. "MoMA's New Home, for Better and Worse". New York Times. Retrieved 30 April 2014.
  10. Michael Dresser (2010-03-22). "Amtrak | At Penn Station, the sign no longer goes clackety-clack". baltimoresun.com. Baltimore Sun. Retrieved 2014-04-30.
  11. http://www.sbb.ch/en/group/the-company/projects/upgrading-the-rail-network/national-projects/modernisierung-generalanzeiger.html
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