Freeway guide signing in Georgia: what old plans say

[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]

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?

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.

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.)

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.

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?

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]

Aside from drawings of cutout shields (at sizes appropriate for independent mount rather than guide-sign use)

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

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).

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?

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.

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.

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.

and I was not able to find it.  Rats!

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?

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.

(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.)

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]

*  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.

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?

[agentsteel53]

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?

my dad took a photo in 1984 of Atlanta's central artery and it shows "exit 246" just where it is today. 

was the plan implemented in phases?

[Alex]

*  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.

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?

Exit numbers were indeed changed in 1999. I remember well Interstate 95 going up to Exit 19 before the changeover.

[agentsteel53]

what does this say, then?  I could've sworn it said exit "246".

(this is a crop of maybe 3% of the area of a 35mm photo.  My dad is clearly not a roadgeek  )

[Bryant5493]

^^

That's exit 246 -- it's the Central Avenue/Fulton Street/Downtown Atlanta/Georgia State University exit, just south of I-20.


Be well,

Bryant

[agentsteel53]

it is exit 246, but does it say that, or does it say some other number corresponding to a sequential numbering?

[Bryant5493]

it is exit 246, but does it say that, or does it say some other number corresponding to a sequential numbering?

Exit 246 used to be sequential exit 91. The exit looks like it might say Georgia Avenue, which is in the same area.


Be well,

Bryant

[agentsteel53]

the exit says "Georgia Avenue" and "Stadium" (old Fulton County Stadium, is my guess) - are 92A and 92B plausible exit numbers for I-20, because if so, that may be what is on that pair.

[Bryant5493]

the exit says "Georgia Avenue" and "Stadium" (old Fulton County Stadium, is my guess) - are 92A and 92B plausible exit numbers for I-20, because if so, that may be what is on that pair.

Georgia Avenue (now Ralph David Abernathy Boulevard) is the exit before Central Avenue/Fulton Street and I-20. I'm assuming I-20 West used to be a left exit, based upon this photo.

Abernathy Boulevard becomes Georgia Avenue again when it crosses Hank Aaron Drive, right across from Turner Field and the old Atlanta-Fulton County Stadium (which is now a parking lot).


Be well,

Bryant

[Alex]

the exit says "Georgia Avenue" and "Stadium" (old Fulton County Stadium, is my guess) - are 92A and 92B plausible exit numbers for I-20, because if so, that may be what is on that pair.

I have video from April 1995 I could check to see what was in place then.

[J N Winkler]

the exit says "Georgia Avenue" and "Stadium" (old Fulton County Stadium, is my guess) - are 92A and 92B plausible exit numbers for I-20, because if so, that may be what is on that pair.

I have re-checked and it seems I allowed myself to be fooled into thinking GDOT had changed to mileage-based exit numbering in 1977 based on the gap between Exit 118 and Exit 120 on I-75 (there was no Exit 119).  This portion of I-75 received what a quick check of Wikipedia confirms were sequential exit numbers in 1977-78.  The signing work was done in GDOT contract number I-75-3(80)251 Ct. 1 (PI 711270-) ("Signs and Exit Numbers:  Interstate Road 75:  Brookwood Station to US 411").  To add to the confusion, at some point in the mid-1970's GDOT dumped cardinal direction suffixes in favor of alphabetical suffixes for interchanges which had multiple exits.  So if, for example, a freeway interchange had had previously had exit numbers of 26E and 26W, these were changed to 26 and 26A, while retaining the overall sequential numbering scheme.  I am not sure whether GDOT ever had to address situations where additional interchanges (which need to get letter suffixes in order to avoid the need to renumber all exits to maintain the sequence) had multiple exits.  Presumably the suffixes for these exits would have been displaced further down the alphabet.

I apologize for my mistake--I should know better than to generalize from a narrow base of evidence.

In regard to the 1980's existence of Exit 246 in the I-75/I-85/I-20 interchange complex, a signing contract from 1976 suggests that the I-20 exits off I-75 were, in fact, Exits 92A and 92B.  The signing contract in question is I-75-2(74)166 (PI 710090-).

Closer examination of the signing contracts suggests that the date for start of exit numbering can be pushed back at least to 1968.  This is based on contract number EHS-I-75-2(64)209 (PI 310022-), which was carried out during 1972 but has sheets showing "existing" signing with cancelled chopblocks dating to 1968.  Based on my understanding of the reprographic technologies used back then, I surmise that the "existing" sheets originally came from an earlier signing contract, carried out in 1968, for which scanned as-builts are not yet available, and that GDOT opted to recycle the older sheets for the newer contract by crossing out all the information that was no longer valid rather than redrawing all of the signs on new sheets.

Interestingly, part of the work done in this contract was to remove exit numbers already installed, probably in the 1968 contract.  The exit numbers to be removed appear to be sequential but are not the same as the sequential numbers later installed.  For instance, the Locust Grove/Hampton exit (probably now signed for "Bill Gardner Parkway") was Exit 68 during the sequential era, and is Exit 212 now, but on the plans with cancelled 1968 chopblocks it is shown as Exit 65.  Similarly, the SR 155/McDonough exit (Exit 69 in the sequential era, Exit 216 now) is shown as Exit 66.  Moreover, exit numbers on these 1968 signs are formatted differently.  The "EXIT XXX" expression is at the top of the sign panel, but not separated from the main sign message by a ruled horizontal line, and the distance expression contains the (redundant) word "EXIT."  The 1972 modifications to these signs deleted the exit number but not word "EXIT" at the top of the sign, added a horizontal ruled line between "EXIT" and the main sign message, and deleted "EXIT" from the distance expression.  The distance expression was re-centered horizontally but "EXIT" at the top of the sign was not, implying that new exit numbers were to be inserted in the future.

[architect77]

Most other states say "Left 3 Lanes", but Georgia says, "3 Right Lanes". Also, GDOT adds "Next 3 Exits" to the center pedestal signs listing upcoming exit distances, stating the obvious....

GDOT also tilts overhead signs down toward the roadway about 5 degrees or so. Makes sense, to catch headlights for reflectivity, but I've never seen other states do this....

[agentsteel53]

GDOT also tilts overhead signs down toward the roadway about 5 degrees or so. Makes sense, to catch headlights for reflectivity, but I've never seen other states do this....

that and it also changes the time of day at which the glare from the sun is the worst to earlier at dawn or later at dusk, when the sun is less bright... if it is up above the tree line in the first place.

[Breadman17]

GDOT also tilts overhead signs down toward the roadway about 5 degrees or so. Makes sense, to catch headlights for reflectivity, but I've never seen other states do this....

Pennsylvania and Arizona do this

[Scott5114]

You didn't need to bump a Georgia thread from 13 years ago to post something that doesn't have anything to do with Georgia.