Date for Change in Signal Colors?

nw-mailing-list at nw-mailing-list at
Sat Jun 25 21:24:34 EDT 2005

Has anyone figured out from the literature the date that the N&W made the
switch from

WHITE for "clear"
GREEN for "approach" or "permissive"
RED for "stop


GREEN for "clear"
YELLOW for "approach" or "permissive"
RED for "stop" ?

The ICC investigation report covering the rear end collision at Belspring on
July 16, 1915, seems to indicate that the change had not yet been made, as
the operator at Pepper wrote "Block Clear" on the Clearance Card when he should
have written "Block Green" (i.e. "permissive") to advance Ex 1425 West into
an occupied block.

I think I recall that it was only about 1912 that Corning Glass Co. figured
out how to make yellow glass that was suitable for railroad signaling purposes
(i.e. chromatically distinct from any shade of red, and having adequate

The answer surely lies in the timetables at the Archives. Git busy, Harry
B. and James B. !!!!

-- abram burnett,
writing from the La-La Land of senile old fuddyduddies
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