Griswold Signal Company

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Griswold Signal Company
Griswold Safety Signal Company
IndustryRailway Signalling, Traffic Signalling
FateMerged with Railroad Accessories Corporation
Founded1923; 96 years ago (1923) in Minneapolis, Minnesota, United States
FounderFranklin Wolcott Griswold
Defunct1964; 55 years ago (1964)
Area served
United States, Canada, New Zealand

The Griswold Signal Company was a manufacturer of traffic signals and railroad grade crossing signals based in Minneapolis, Minnesota. The company was founded by Minnesota native Frank W. Griswold, one of thirteen children born to attorney and local landowner Franklin C. Griswold.


Bobby signal[edit]

Griswold got his start in 1923 with the invention of the "American Bobby," a traffic signal designed for placement in the middle of an intersection that would collapse if struck by a vehicle. Many bobby signals were sold to municipalities throughout North America; this led to the development of the rotating banner signal.

Rotating banner signal[edit]

In 1927, Griswold introduced the rotating banner signal. This was a unique combination of highway flasher and rotating stop sign. An approaching train would trigger not just the requisite red flashing lights and bells, but a mechanism that rotated a yellow stop sign ninety degrees to face traffic as well. (The signs eventually changed to red.)[1] This type of signal was relatively common throughout the Midwestern United States, where state regulators required use of the design. Some were also installed in the Western United States, especially along the Great Northern, Milwaukee Road, and Southern Pacific.

Surviving signals[edit]

Griswold signals on 22nd Avenue NE, Minneapolis, in 2018

As of November 2016, there are only half a dozen known Griswold signals still in service along active rail, all in Minnesota, none with rotating stop sign signals. The last pair with an operating banner protected 22nd Ave NE in Minneapolis, Minnesota. The Griswolds in Tacoma, Washington and San Jose, California were both removed circa 2010.

Magnetic Signal Company[edit]

The firm purchased Los Angeles-based Magnetic Signal Company in the late 1940s and moved production to Minneapolis. Magnetic Signal is the company credited with the invention of the wigwag grade crossing signal once common throughout Southern California.

Railroad Accessories Corporation[edit]

Railroad Accessories Corporation (RACO) merged with Griswold Signal Company in 1964. Manufacturing of crossing signals continued in Minneapolis.

Safetran Systems[edit]

RACO and Marquardt Industrial Products merged in 1971 to form Safetran Systems. Management, sales, and manufacture of crossing signals continued in Minneapolis until 2000, when the division moved to Kentucky.

External links[edit]


  1. ^ See a photo of one without the lights at