Green Bus Interstate Shield

[sammack]

Anybody have any idea as to the origin of the green shield?

Why would they use something that has the same green as the guide sign.  Providing no contrast.

[agentsteel53]

the business loop shield was introduced in a June 27 1958 addition to the then-circulating February 22 1958 revision of the Oct 1957 AASHO interstate manual. 

I have an example of this manual, and the business loop insert is a single double-sided page stapled in the front cover.

the reason for its greenness (specified "standard Interstate green", defined as the exact same color as the background) was so that it matched the outline shields that were specified in 1957 for US and state routes.  Basically, you ended up with an interstate outline shield, and that was the intent.

The 1961 manual went to white shields because drivers were getting confused by the mismatch in color between guide-sign and surface-mounted shields.  Since the business loop shield was green even when mounted on a pole, there was no reason to change its color.  Maybe it should've been changed to white then ... as the vast majority of state and US shields at the time were white.

[yakra]

...the outline shields that were specified in 1957 for US and state routes.

I'm curious to hear more about this...

[agentsteel53]

I'm curious to hear more about this...

I'll dig up a scan at home - the 1957 AASHO manual specified outline shields on the green signs.  Examples were shown for US routes; state routes were to be "fundamentally similar". 

here's an example from Pennsylvania:



this is a non-standard shield shape.  The 1957 AASHO manual uses the 1948 shield shape (classic US shield, just no crossbar) while this is some variant.  Stimsonite, the button-copy manufacturer, came out with this shape in 1957, that was used in many states.  Here is a Colorado example:



the standardized use of a slightly wider than tall US route shape for both two and three digit routes was not formalized until 1961, with the white shields.

here are outline-shield state route signs from Missouri.