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Author Topic: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs  (Read 13380 times)

jeffe

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Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« on: April 18, 2021, 03:48:13 AM »

Caltrans updated the standard plans on 16 April 2021 to now include external exit tabs. It's plan S122 and they are officially called an Exit Plaque.

All of the overhead sign structures have been redesigned.  There used to be separate sign structures for standard signs and CMSs.  These have been consolidated into a new sign structure called the Versatile Truss.

The Versatile Truss comes in three different heights, or frame depths -- 60, 72, and 120 inches tall.  These allow for a maximum sign height of 80, 180, and 240 inches, respectively.

Placing a 240 inch sign on a 120 inch structure will of course have considerable overhang.  The sign panel will be centered vertically on the structure, as the overhang is designed to be equal above and below the sign structure.

This will lead to much larger sign panels being available for use on California freeways.  They will also look different because the sign panels will extend below the bottom of the sign structure as they do in some other states.
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #1 on: April 18, 2021, 12:07:11 PM »

You have some example images of this update? Want to see how the new BGS design compares to what I see in other states.
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #2 on: April 18, 2021, 12:59:54 PM »

it's not April 1

jeffe

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #3 on: April 18, 2021, 02:55:52 PM »

You have some example images of this update? Want to see how the new BGS design compares to what I see in other states.

I haven't seen any of these new sign structures out in the wild yet, but here is some info from the standard plans:




The updated standard plans are available here: https://dot.ca.gov/-/media/dot-media/programs/design/documents/locked_2018-entire-revised-standard-plans-260-sheets-april-2021-a11y.pdf.  The versatile truss plans start on page 222 of that PDF.

All of the examples show sign panels of equal height; I don't see anywhere that makes that a requirement though.

Quote
The Versatile Truss is a new truss design. It replaces the changeable message sign
(CMS) overhead sign truss. The Versatile Truss can accommodate sign panels (up to 240
inches tall), exit plaques (up to 60 inches tall), changeable message signs (CMS), and
extinguishable message signs (EMS).

The original standard overhead truss on Standard Plan sheets S1 through S22 will remain
available in the Standard Plans during a limited transition period. Projects should begin to
callout the Versatile Truss as soon as possible. The original Standard Plan truss will
eventually be discontinued from the Standard Plans.

Source: https://dot.ca.gov/-/media/dot-media/programs/engineering/documents/standardplanuserguides/versatile-truss/20200112-versatiletrussug_a11y.pdf
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #4 on: April 18, 2021, 05:14:35 PM »

Are these mirrored for some reason or will all the exit number plaques be on the left -_-

Max Rockatansky

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #5 on: April 18, 2021, 05:28:53 PM »

I was kind of liking how the exit tabs in-sign were getting messed up like this:

https://flic.kr/p/2kMKL2N
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jeffe

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #6 on: April 18, 2021, 07:37:43 PM »

Are these mirrored for some reason or will all the exit number plaques be on the left -_-

I think the left mounted exit plaques are there to show a maximum wind loading situation.  The left side plaques will be twice as tall as a right plaques to allow for a LEFT plaque to be placed above the exit number.




I was kind of liking how the exit tabs in-sign were getting messed up like this:
https://flic.kr/p/2kMKL2N

Haha, yeah that sign looks great  :p 
The FHWA has given a hard no to using in-sign exit tabs:
https://mutcd.fhwa.dot.gov/reqdetails.asp?id=359
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #7 on: April 18, 2021, 07:44:23 PM »

^^^

Even more reason why Exit 23.9 is the best thing to happen Interstate 15 and Zzyzx in decades.  Really MUTCD adherence and California (both Caltrans and the DOH) have never really ever seen eye to eye on much of anything.  That’s why it totally wouldn’t shock me if the left Exit tab as illustrated above is real.

FWIW the above statement shouldn’t be taken as a complaint by me about MUTCD adherence in California.  I love interesting and weird signs, California has certainly been a treasure trove over the years.
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jeffe

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #8 on: April 18, 2021, 07:55:15 PM »

Digging a little deeper, it looks like right exits will have right aligned plaques and left exits will have left aligned plaques.  No center aligned plaques here. :p

Quote
Exit number (E1-5P) plaques should be added to placed above and abutting the top righthand edge of the sign for an exit to the right.
Standard:
Because road users might not expect an exit to the left and might have difficulty in
maneuvering to the left, a left exit number (E1-5bP) plaque (see Figure 2E-22) shall be
added to placed above and abutting the top left-hand edge of the sign for all left-hand exits
(see Figures 2E-14 and 2E-15). The word LEFT on the E1-5bP plaque shall be a black
legend on a yellow rectangular sign panel and shall be centered above the word EXIT.

Source: https://dot.ca.gov/-/media/dot-media/programs/safety-programs/documents/ctcdc/july-9-2020/final-ctcdc-july9-2020-agenda-a11y.pdf (Page 14)
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #9 on: April 18, 2021, 11:16:47 PM »

The FHWA has given a hard no to using in-sign exit tabs:
https://mutcd.fhwa.dot.gov/reqdetails.asp?id=359

In that case the FHWA needs to start looking at Washington, Illinois, etc. (As far as I know, Georgia no longer has any left-exit signs with in-sign exit numbers.)
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #10 on: April 18, 2021, 11:22:39 PM »

The FHWA has given a hard no to using in-sign exit tabs:
https://mutcd.fhwa.dot.gov/reqdetails.asp?id=359

In that case the FHWA needs to start looking at Washington, Illinois, etc. (As far as I know, Georgia no longer has any left-exit signs with in-sign exit numbers.)
Also Michigan, which uses both. From what I heard, full length tabs in Michigan are installed on signs that are shorter than the gantry's height, while those taller use side tabs.
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #11 on: April 18, 2021, 11:33:23 PM »

But what about wind loading?

jdbx

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #12 on: April 19, 2021, 03:45:49 PM »

Wow!!  It only took ~20 years since California started numbering exits to actually start doing it right.  The way exit tabs were jammed into signs while keeping existing legends looked awful, especially in urban areas where message loading within the sign was already pretty high.

I can't wait to see the first new design on a versatile truss out in the wild.

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #13 on: April 19, 2021, 06:42:24 PM »

Wow!!  It only took ~20 years since California started numbering exits to actually start doing it right.  The way exit tabs were jammed into signs while keeping existing legends looked awful, especially in urban areas where message loading within the sign was already pretty high.

I can't wait to see the first new design on a versatile truss out in the wild.



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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #14 on: April 19, 2021, 07:05:18 PM »

That's an example of an external exit tab, but the OP is also about 240-inch height signs. I'm guessing that Caltrans hasn't installed any of those yet.

In that case the FHWA needs to start looking at Washington, Illinois, etc. (As far as I know, Georgia no longer has any left-exit signs with in-sign exit numbers.)
Also Michigan, which uses both. From what I heard, full length tabs in Michigan are installed on signs that are shorter than the gantry's height, while those taller use side tabs.

The easy way to fix that problem for Michigan is to only make signs with height that is equal to or more than the gantry height even if that results in blank space on the sign.

(Or just make the sign normally. Plenty of states allow a sign to be shorter than the gantry, such as NC)
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jeffe

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #15 on: April 19, 2021, 08:13:16 PM »

I can't wait to see the first new design on a versatile truss out in the wild.



Great photo of external exit plaques Occidental!

However, the sign structure in that photo is actually a standard sign truss and not a versatile truss. 


Standard Sign Truss:

The verticals and diagonals are attached directly to the top and bottom chord.


Versatile Sign Truss:

With a versatile sign truss the verticals and diagonals are attached to a gusset plate, which it in turn attached to the top and bottom chords.

Closeup of the Gusset Plate:


I don't think there are any versatile sign trusses installed yet, but anyone please send along a photo if you see one!

« Last Edit: April 20, 2021, 02:48:06 AM by jeffe »
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #16 on: April 19, 2021, 09:25:30 PM »

So the only thing Caltrans needed to solve their "wind loading" problems is a feature that's been a part of the standard KDOT gantry since before I was born??
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Alps

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #17 on: April 20, 2021, 12:37:57 AM »

Wow!!  It only took ~20 years since California started numbering exits to actually start doing it right.  The way exit tabs were jammed into signs while keeping existing legends looked awful, especially in urban areas where message loading within the sign was already pretty high.

I can't wait to see the first new design on a versatile truss out in the wild.




Of course the "ONLY" is still a problem  :rolleyes:

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #18 on: April 20, 2021, 03:29:39 AM »

I may be one of the few that likes CalTrans' internal exit tabs, but given how it can lead to cramped and ultimately 'busy' signage, the new external designs are welcome, especially if the CA 57 at CA 91 BGS shown above is anything to go by.
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #19 on: April 20, 2021, 12:00:32 PM »

So the only thing Caltrans needed to solve their "wind loading" problems is a feature that's been a part of the standard KDOT gantry since before I was born??

I still think the wind loading explanation is a bit of BS. Nevada DOT has had a standard truss design nearly identical to Caltrans' for ages, and NDOT has had external tabs for years as well as signs taller than 120" for at least a couple decades...
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #20 on: April 20, 2021, 12:36:23 PM »

I may be one of the few that likes CalTrans' internal exit tabs, but given how it can lead to cramped and ultimately 'busy' signage, the new external designs are welcome, especially if the CA 57 at CA 91 BGS shown above is anything to go by.

I like them too, but the picture of the new exit tabs looks just as good. Only loss here is it'll no longer be unique.
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #21 on: April 20, 2021, 07:14:56 PM »

Wow, this is quite an update.

For the life of me, I don't know of any situation where a 20 foot tall sign is going to be needed in California.  I know there are some in other states but those mostly revolve around some monstrous diagrammatic signs.  I believe California's Express Lane signs that display the current toll are 150" in height.  Heck, even the FHWA example APL is less than 180 inches in height.  I guess CalTrans over-engineered the 120" versatile truss so it can accommodate whatever weird requirements the FHWA hands down next.  I do hope the policy of all signs on a truss be of the same height will remain.  With them going to external tabs, I think it will drastically improve sign layouts.

As a connoisseur of all-things CalTrans, I'm in the process of adding this truss to my sign-making library.  I just completed the 120" truss (capable of holding a max-height guide sign of 240") but I'm still working on the 60" and 72" versions.
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #22 on: April 21, 2021, 12:25:15 AM »

Wow, this is quite an update.

For the life of me, I don't know of any situation where a 20 foot tall sign is going to be needed in California.  I know there are some in other states but those mostly revolve around some monstrous diagrammatic signs.  I believe California's Express Lane signs that display the current toll are 150" in height.  Heck, even the FHWA example APL is less than 180 inches in height.  I guess CalTrans over-engineered the 120" versatile truss so it can accommodate whatever weird requirements the FHWA hands down next.  I do hope the policy of all signs on a truss be of the same height will remain.  With them going to external tabs, I think it will drastically improve sign layouts.

As a connoisseur of all-things CalTrans, I'm in the process of adding this truss to my sign-making library.  I just completed the 120" truss (capable of holding a max-height guide sign of 240") but I'm still working on the 60" and 72" versions.
The LA, SF, and Sacto areas all have complicated enough interchanges that I can see 20' happening. As a sign designer, I find that normal messages are in the 12'-13' range, so it doesn't take a whole lot.

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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #23 on: April 21, 2021, 12:29:30 PM »

Mixed feelings on 240" signs. It can make layout less cluttered, but I don't want it if that brings those ugly MUTCD APL signs to California.

(Note: reason for not liking APL signs is the large amount of blank space)
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Re: Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs
« Reply #24 on: April 21, 2021, 03:12:15 PM »

OK, so here is my version of the new versatile truss design that Caltrans released earlier this week.  The differences between the old and new versions are quite interesting.

First, the current truss design...

Now the new truss design...

Main differences in the new design include beefier chords and vertical and diagonal components.  The thickness of the chord was increased from 6 inches to 8 inches.  The vertical and diagonal components were also increased from 3 inches to 5.  Looking at the new standard plans, these trusses can handle 100 MPH wind speeds and there are soil parameters that must be met before this type of structure can be installed.

Finally, here's a sample I whipped up using the new truss, a 120-inch tall BGS and a 240-inch tall BGS.

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