Caltrans External Exit Tabs & 240 Inch Tall Overhead Signs

[jakeroot]

I would imagine the reason they went with a two-line tab is because, with a one line tab, it is too easy to get into a situation where the tab is wider than the main panel is. (LEFT EXIT 149A ... Jones)

I'm not sure about that. If it were an issue of the exit tab potentially being too wide, they should allow for the "LEFT" legend to be placed either next to or above, not always next to.

And if size was really an issue, why not experiment with alternative design options? Such as (a) exit tabs with black-on-yellow text to symbolize a left exit, or even (b) replacing the words with a symbol pointing left or right?

I'm pretty sure I read that the FHWA specifically wanted the "LEFT" legend to be stacked for improved recognition of the condition. Still, I'm insanely skeptical it makes any difference.

[vdeane]

I wouldn't be surprised if the extra height of having "LEFT" on top helps to draw attention to it as well.

[jakeroot]

I wouldn't be surprised if the extra height of having "LEFT" on top helps to draw attention to it as well.

Most likely. But then, of course it would stand to reason that if we made every sign a hundred feet tall, of course no one would miss it.

Exaggerating slightly less: as much as I love APLs, I'm sure the extra sign area plays a role there, too.

I feel like there's a certain art in sign design that's being completely disregarded when it comes to LEFT exit tabs.

[Scott5114]

I've always felt like the real best practice would be to use the independent "LEFT" tab (which is intended for unnumbered left exits) and stack it on top of a standard exit tab.

[jakeroot]

I've always felt like the real best practice would be to use the independent "LEFT" tab (which is intended for unnumbered left exits) and stack it on top of a standard exit tab.

I would have assumed this was already allowed.

I think it's a good interim solution, but I feel the best long-term solution is something that doesn't involve literally spelling out "LEFT". Something with color, or a symbol. Something else that doesn't require our highway signs to have top edges that look more like a mountain range.

[flaminhotfrank]

I honestly wish they just posted the exit numbers in the gore and posts of the gantry, like they do on the signs with really short truss heights. It would've allowed for more button copy signs to stay up and still have exit numbering. Really pisses me off when they replace button copy that has more lifespan to it/in good condition, only to leave the most decrepit, discolored sign you have ever seen. 

[Techknow]

I just came back from a trip to Lake Tahoe and saw several external exit tabs, here they are! These are all dashcam photos that I don't mind sharing, the GPS coordinates basically geolocate them on any Maps application.

Honestly these exit tabs are like the ones I have seen from other posters and those that I have posted myself, and they all look oversized and more or less terrible. I have yet to see an exit tab like the one discovered on CA 57

All of them were in I-80 going westbound:

Exit 184 at Truckee



Exit 94 at Sacramento (it was posted here first!)







Exits 14B and 15 at Richmond

[roadfro]

The Donner Pass Road one I think may be a completely new installation, so that somewhat makes sense.

Most of the others are interesting in that there are external exit tabs on what appear to be existing gantries. It looks like they may have reduced the size of existing signs to add exit tabs, so that external tabs can be used without significant difference to the wind loading of the sign structure. But that last Light Rail Stations sign has that huge tab on an undersized gantry that the signs don't appear (and really couldn't get) any smaller, so I wonder how that came to pass.

[myosh_tino]

The Donner Pass Road one I think may be a completely new installation, so that somewhat makes sense.

That one and the stand-alone Light Rail Stations sign are new and use the new versatile truss where the sign panel is centered on the truss.  All the other ones are mounted to an existing gantry which I thought was a no-no

But that last Light Rail Stations sign has that huge tab on an undersized gantry that the signs don't appear (and really couldn't get) any smaller, so I wonder how that came to pass.

That exit tab is almost as tall as the sign.  And yes, I too am wondering how that was allowed to happen.

[Scott5114]

The main panel of the Carlson and Cutting signs aren't using the full 120" height of the gantry (I'm eyeballing the Carlson sign as only being 56" or so high). Given that, their wind loading calculations must have shown that the sign was fine to be mounted to an existing gantry.

[cl94]

The Donner Pass Road one I think may be a completely new installation, so that somewhat makes sense.

.

It is. Several new gantries went up in the Truckee area in 2023, all of which have external tabs. I have a feeling that will be the standard from District 3 moving forward given how many new installs I have seen in the past year.

I still think the wind loading stuff seems like a bunch of BS used to excuse an unwillingness to change, given that Nevada uses the same damn gantries with external tabs and tall signs in some pretty windy locations.

(personal opinion emphasized)

[roadfro]

I still think the wind loading stuff seems like a bunch of BS used to excuse an unwillingness to change, given that Nevada uses the same damn gantries with external tabs and tall signs in some pretty windy locations.

(personal opinion emphasized)

I've also thought the wind loading rationale was also bunk, for the exact same reason.

[Max Rockatansky]

All the same, I can understand finding a rationale not to alter existing/programmed sign gantries for external exit tabs of all things.  I don't see much more than nominal value, I would imagine some at Caltrans feel the same way.

[roadfro]

All the same, I can understand finding a rationale not to alter existing/programmed sign gantries for external exit tabs of all things.  I don't see much more than nominal value, I would imagine some at Caltrans feel the same way.

I totally get that, and agree with you there as well. I had no problem CalTrans' implementation of internal exit tabs as a stopgap solution, because at least it was something.

But it's also kinda ridiculous that it took nearly 20 years after beginning the Cal-NExUS exit numbering program for external exit tabs to make it into California. And that wind loading was the excuse, when Nevada has been using the same trusses with external exit tabs without issue as long as I've been alive...

[fwydriver405]

I've always felt like the real best practice would be to use the independent "LEFT" tab (which is intended for unnumbered left exits) and stack it on top of a standard exit tab.

I would have assumed this was already allowed.

Not to get too off-topic and/or if this is what you're talking about, but Massachusetts (since the mid 2000s) and I think Michigan too use this "LEFT" exit tab style - stacked above the normal exit tab.

However, MassDOT actually removed some of those tabs in the summer of 2023 in the eastern part of the state (example on MA 24 before, after) - no official reasoning has been given, but could be attributed to a sign falling down on I-93 in Dec 2022, which did prompt DOT to erect smaller signs on that stretch of I-93 (before, after).

Some of the left exit tabs have actually returned after their removal, but with reinforced brackets on the tab (before, after).

[Techknow]

Thanks all for these insights about the trusses and the signs. My road trip that day was full of rain and high winds thanks to an atmospheric river. I later read that winds in the Sierras topped out at 165 MPH. I don't know how strong the winds were around Donner Summit/I-80 that time, but I'm convinced the (versatile) trusses and signs were engineered to be robust enough against such weather. I don't have much understanding yet about the wind loading context but I can educate myself on it

As for the "oversized" external exit tabs I saw, they might make sense to me. I became curious as to what exit tabs looked like outside of California, and it looks like some states have big external tabs (lots of examples in the Road Sign UNO thread) while other states use tabs the size of "internal" exit tabs seen on Caltrans BGSes, and of course some states use internal exit tabs too. Honestly, having only driven around or lived in California save for a few exceptions, I was so used to how small and squished the internal exit tabs are that my expectations of the external exit tabs appearing here and there are kinda off.

[ran4sh]

All states are supposed to use 30-inch height exit tabs, because that's what the MUTCD specifies. However, this standard is only 2 decades old, in the mid-00s the standard was 24-inch height. Since there are numerous signs that were installed and/or designed before the change, that is why those signs have smaller looking tabs.

[TheStranger]

Thought of this thread last night as I was going home on I-80 in San Francisco:

The large left exit external tab for the westbound advance Harrison Street overhead sign on the Bay Bridge has fallen off!

SM-S901U1