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Freeway guide signing in Georgia: what old plans say

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J N Winkler:
I have spent a few hours examining old GDOT freeway guide signing plans.  Here is what I have been able to find out:

*  GDOT was installing permanent guide signing for its Interstates by 1960.  The initial signing scheme called for distance expressions of the form "EXIT 1 MILE," a final advance guide sign with "RIGHT LANE" (or "LEFT LANE" as appropriate), and an exit direction sign with the arrow generally positioned at the bottom of the sign panel.

*  GDOT began numbering exits around 1970.  Initially the numbering was sequential with cardinal direction suffixes for interchanges having multiple exits, and tabs (generally full-width with the exit number centered) were attached to existing sign panels.  Exit numbers were also generally retrofitted onto gore signs.  GDOT took the opportunity to revise the distance and exit indication messages on the existing advance guide signs, generally by deleting the word "EXIT" in distance legends ("1 MILE" in lieu of "EXIT 1 MILE") and by replacing "RIGHT LANE" with "NEXT RIGHT."  Most of the contracts to perform this retrofit work had "safety modification" in their titles.  Where overhead guide signs were concerned, GDOT generally (but not always) reused the existing sign structures.

*  GDOT changed to mileage-based exit numbering around 1977.  As far as I can tell, this was done primarily by revising messages (removing old legend and installing new legend) on the existing guide signs.

*  In the 1960's and 1970's (and possibly later), GDOT used basically two forms of aluminum sign construction.  One was laminated aluminum (i.e., phenol-impregnated paper honeycomb between two sheets of flat aluminum, with porcelain enamel finish on the side facing traffic), while the other consisted of aluminum extrusions bolted together with rounded edge moldings.  GDOT laminated panels were more or less identical to those used contemporaneously by PennDOT and Caltrans, while the use of rounded side moldings on extruded aluminum signs is very similar to what Oklahoma DOT does now.

*  In 1970, GDOT mileposts were unbordered and consisted just of the mileage (no word "MILE" at top) ranged vertically, and immediately beneath, the number of the state route ranged horizontally in a much smaller typeface (6" Series D for the mileage and 1" Series D for the state route number).  By 1972 the design had been changed to incorporate a white border and "MILE" (4" Series C) at the top.

*  I had previously assumed that GDOT had decided to change from 16" uppercase/12" lowercase Series E Modified to 20" uppercase/15" lowercase Series D (mixed-case) in the mid-1990's largely on the basis of research (notably a report by McGee et al. which I think was published in 1990) suggesting that a conversion from 16"/12" to 20"/15" (including on overhead guide signs) would be necessary at some point in the future in order to accommodate older drivers.  It seems, however, that GDOT was already using mixed-case Series D by 1987, so the McGee study seems to have trailed rather than led the GDOT change.

agentsteel53:
do you have any data on materials used?  Button copy vs retroreflective?  Also, if the shields themselves ever featured button copy (I have not ever seen a photo of a button-copy shield on a green sign in GA), and what the specifications for their shape were?

would be interesting to see if they ever used button copy Series D letters.  I've never seen an example of that.  (I do know AGA offered the uppercase alphabet, have never seen lowercase.)

Noting the existence of mixed-case D in 1987: does this mean there was a federal standard for lowercase D by then, or did Georgia make up their own or borrow one from another state?

J N Winkler:

--- Quote from: agentsteel53 on May 15, 2010, 10:54:48 AM ---do you have any data on materials used?  Button copy vs retroreflective?  Also, if the shields themselves ever featured button copy (I have not ever seen a photo of a button-copy shield on a green sign in GA), and what the specifications for their shape were?
--- End quote ---

Aside from drawings of cutout shields (at sizes appropriate for independent mount rather than guide-sign use), a standard plan sheet indicating that laminated panel signs were to have demountable button-copy borders, and a late 1980's update of the laminated panel standard sheet indicating that the aluminum sheets were to be .063" on the traffic side and .040" on the back, no.  There could very well have been a separate set of standard plan sheets (some state DOTs have separately bound standard plan sheets and "insertable sheets" which are actually inserted in the construction plans set) or possibly a signs manual incorporated into the contract by reference in the special provisions.  There are not even detailed drawings for the guide sign route markers, which you do get with Arizona DOT and PennDOT signing plans of similar vintage.

My guess, based on the photos of Georgia freeway guide signs I have seen, is that older signs with opaque (nonreflective) background had demountable button copy (mixed-case Series E Modified for primary legend and probably "Series D Modified" for all-uppercase legend) and fully retroreflective shields (digits silkscreened onto the guide-sign Georgia and US route markers).  Later, when GDOT moved toward retroreflective green background, this more or less coincided with the change toward mixed-case Series D.  All non-black sign elements were cut out of retroreflective sheeting, and no mixed-case button copy version of Series D was used.


--- Quote ---would be interesting to see if they ever used button copy Series D letters.  I've never seen an example of that.  (I do know AGA offered the uppercase alphabet, have never seen lowercase.)
--- End quote ---

I don't think there was ever a mixed-case button-copy Series D (or even Series D Modified).  My reason for this surmise is that, after Caltrans' Great Redrawing of 1971, "U.C." paired with "L.C." on sign spec sheets was code for the button-copy version of what we now know as Series E Modified, while "CAPS" was code for Series D Modified in button copy.  In that context it would be eccentric, to say the least, to specify a "CAPS" alphabet when the alphabet in question does have lowercase letters in button copy.

An AGA catalogue would confirm the nonavailability of button-copy lowercase "Series D Modified," but the only place I know has a copy is the Caltrans library and I missed my chance to photograph it.


--- Quote ---Noting the existence of mixed-case D in 1987: does this mean there was a federal standard for lowercase D by then, or did Georgia make up their own or borrow one from another state?
--- End quote ---

Nope, there wasn't a federal standard--lowercase letters for all alphabets except Series E Modified were unapproved extensions until well after 2000.  My best guess, as noted in the thread dealing with this issue, is that the glyphs were informally circulated among state DOTs and the signing industry (I am not sure which was the first to develop lowercase alphabets or how well standardized they were).

A question for you:  have you ever succeeded in getting a state DOT to admit that they used a custom font in the past, and to send you drawings of the letters?  (It makes me queasy to acknowledge that custom fonts existed and were used, because that offends my sense of orderliness and consistency.  But even setting aside the photographic evidence, which cannot be denied, custom fonts did make their way onto standard plan sheets in places like Michigan and California.)

agentsteel53:

--- Quote from: J N Winkler on May 15, 2010, 01:10:27 PM ---Aside from drawings of cutout shields (at sizes appropriate for independent mount rather than guide-sign use)
--- End quote ---

can you by any chance get me these pages?  I'd really like to see them.


--- Quote ---My guess, based on the photos of Georgia freeway guide signs I have seen, is that older signs with opaque (nonreflective) background had demountable button copy (mixed-case Series E Modified for primary legend and probably "Series D Modified" for all-uppercase legend) and fully retroreflective shields (digits silkscreened onto the guide-sign Georgia and US route markers).
--- End quote ---

this makes sense, given what I have observed. I've seen 1961-spec shields on button copy signs that were, themselves, retroreflective instead of button copy.



were the interstate shields made by layering retroreflective colored elements on top of each other, or were they printed?


--- Quote ---I don't think there was ever a mixed-case button-copy Series D (or even Series D Modified).  My reason for this surmise is that, after Caltrans' Great Redrawing of 1971, "U.C." paired with "L.C." on sign spec sheets was code for the button-copy version of what we now know as Series E Modified, while "CAPS" was code for Series D Modified in button copy.  In that context it would be eccentric, to say the least, to specify a "CAPS" alphabet when the alphabet in question does have lowercase letters in button copy.
--- End quote ---

I will have to look through the Caltrans spec sheets to see where they use Series DM button copy.  Some of the mileage signs have the numbers in DM, but that is the only example I can think of offhand.


--- Quote ---An AGA catalogue would confirm the nonavailability of button-copy lowercase "Series D Modified," but the only place I know has a copy is the Caltrans library and I missed my chance to photograph it.
--- End quote ---

and I was not able to find it.  Rats!


--- Quote ---A question for you:  have you ever succeeded in getting a state DOT to admit that they used a custom font in the past, and to send you drawings of the letters?
--- End quote ---
never, but my interaction with state DOTs is much more limited than yours.  I tend to go after the sign collectors and historians more than the DOTs.


--- Quote ---(It makes me queasy to acknowledge that custom fonts existed and were used, because that offends my sense of orderliness and consistency.  But even setting aside the photographic evidence, which cannot be denied, custom fonts did make their way onto standard plan sheets in places like Michigan and California.)

--- End quote ---

I have never seen a custom-font sign in California more recent than 1956 or so, with the exception of what I am assuming are contractor errors, or local issue. 



there is this 128 that is almost unique (somewhere near there, there is another one and I forget which number it is) and I am guessing some contractor took extra liberties.  I have seen the custom fonts on the Caltrans signage sheets, but I thought they were not intended to be pattern-accurate, as I have never seen a consistent application of a non-standard font set more recent than the porcelain days. 

I believe the old porcelain fonts tended to be carried forward (see 1956 California US marker, with block fonts for everything but the number, for example) simply because CAMEO already had the stencils made and saw no need to upgrade. 

as for the retroreflective, button-copy, and post-1957 porcelain signs - as far as I know, they've all used FHWA 1948 (plus the Modified variants) alphabets.

Eth:

--- Quote from: J N Winkler on May 15, 2010, 10:30:42 AM ---*  GDOT changed to mileage-based exit numbering around 1977.  As far as I can tell, this was done primarily by revising messages (removing old legend and installing new legend) on the existing guide signs.

--- End quote ---

Are you sure about this?  I ask because I grew up in Georgia myself during the 1990s, and all Interstate exit numbers were still sequential at that time.  I remember it being a fairly big deal when it was announced in either 1999 or 2000 that the numbers would be changing.  Did GDOT change to mileage-based earlier and then change back?

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