Overhead Signs with External Exit Tabs?!?

[myosh_tino]

About a month ago I was headed north on I-5 when I noticed that Caltrans installed new signs prior to the I-5/CA-120 interchange.  What caught my eye was this...





... so because I was in the area again today, I snapped the above two pictures.

Now I know that there are a number of ground-mounted guide signs that feature separate exit tabs and there are a few in southern California but this is the first time I've personally seen separate exit tabs on overhead signs.  Doing some quick measurements, I am able to determine these tabs are 24 inches tall which is undersized by MUTCD-standards but correct under current Caltrans policy.  The signs in the first photo are 110" tall and 100" tall in the second photo.

I'm not sure if this is any indication that the use of external tabs is going to become the norm in California or they were just an "experiment".  Perhaps jrouse can shed some additional light on the matter.

[roadfro]

Interesting...

Other than the old exit numbering experiment from way back, I've never seen overhead signs in California with external exit tabs. Hopefully it's a sign of new things to come (it would really help towards Caltrans not having so many "squished" sign designs as is common under current standards).

[TravelingBethelite]

About a month ago I was headed north on I-5 when I noticed that Caltrans installed new signs prior to the I-5/CA-120 interchange.  What caught my eye was this...





... so because I was in the area again today, I snapped the above two pictures.

Now I know that there are a number of ground-mounted guide signs that feature separate exit tabs and there are a few in southern California but this is the first time I've personally seen separate exit tabs on overhead signs.  Doing some quick measurements, I am able to determine these tabs are 24 inches tall which is undersized by MUTCD-standards but correct under current Caltrans policy.  The signs in the first photo are 110" tall and 100" tall in the second photo.

I'm not sure if this is any indication that the use of external tabs is going to become the norm in California or they were just an "experiment".  Perhaps jrouse can shed some additional light on the matter.

Never thought I'd see the day. 

[jakeroot]

I prefer internal exit tabs because they keep information within the sign to a minimum. I think of them as sort of a watchdog towards preventing busy signs. If you can't figure out how to fit everything into the sign, then you need to rethink the sign or move the sign to a different gantry where there's more room.

[TravelingBethelite]

I prefer internal exit tabs because they keep information within the sign to a minimum. I think of them as sort of a watchdog towards preventing busy signs. If you can't figure out how to fit everything into the sign, then you need to rethink the sign or move the sign to a different gantry where there's more room.

I personally don't believe that the internal/external exit tabs have anything to do with cluttered/"busy" signs. It's the content of the sign that really matters. The pictured signs are great, regardless! 

[jakeroot]

I prefer internal exit tabs because they keep information within the sign to a minimum. I think of them as sort of a watchdog towards preventing busy signs. If you can't figure out how to fit everything into the sign, then you need to rethink the sign or move the sign to a different gantry where there's more room.

I personally don't believe that the internal/external exit tabs have anything to do with cluttered/"busy" signs. It's the content of the sign that really matters. The pictured signs are great, regardless! 

I agree, yes, the content is most important. But there's a point where too much content can become overload, and cause driver confusion. So, based on that, any method that helps keep info on the sign to a minimum gets my vote.

[roadman65]

I prefer internal exit tabs because they keep information within the sign to a minimum. I think of them as sort of a watchdog towards preventing busy signs. If you can't figure out how to fit everything into the sign, then you need to rethink the sign or move the sign to a different gantry where there's more room.

I personally don't believe that the internal/external exit tabs have anything to do with cluttered/"busy" signs. It's the content of the sign that really matters. The pictured signs are great, regardless! 

I agree, yes, the content is most important. But there's a point where too much content can become overload, and cause driver confusion. So, based on that, any method that helps keep info on the sign to a minimum gets my vote.

I agree as the airports are the best example of that.

[kurumi]

I'm on the side of not liking internal/fake exit tabs and not believing that they have instilled any sort of layout discipline in the Golden State. Drive around the 237/880 interchange in Milpitas for examples.

But maybe the door is cracking open. On CA 237 in Sunnyvale, approaching 101, is a sign bridge where the panels are not the same height: https://goo.gl/maps/JglgK

20 years ago, exit numbers were not going to happen; and look where we are now.

[myosh_tino]

But maybe the door is cracking open. On CA 237 in Sunnyvale, approaching 101, is a sign bridge where the panels are not the same height: https://goo.gl/maps/JglgK

Hmmm... the CA-237 pull-through and the US 101 south exit signs were new ones installed during the conversion of CA-237 to a full freeway back in the early 90's.  Both of these signs are 110 inches tall.  Caltrans retained the existing 100 inch tall US 101 North/Mathilda Ave sign and squished it between the two new signs.  If you zoom in on the GMSV image kurumi linked to, you'll see that the US 101 South sign overlaps the older US 101 North advance guide sign.

[vdeane]

I prefer internal exit tabs because they keep information within the sign to a minimum. I think of them as sort of a watchdog towards preventing busy signs. If you can't figure out how to fit everything into the sign, then you need to rethink the sign or move the sign to a different gantry where there's more room.

It would seem that the internal tabs combined with every sign being the same height would be the CAUSE of CA's squashed, busy signage.

[roadfro]

I prefer internal exit tabs because they keep information within the sign to a minimum. I think of them as sort of a watchdog towards preventing busy signs. If you can't figure out how to fit everything into the sign, then you need to rethink the sign or move the sign to a different gantry where there's more room.

It would seem that the internal tabs combined with every sign being the same height would be the CAUSE of CA's squashed, busy signage.

I would agree with this.

California generally isn't prone to try and add too many extraneous destinations and street names onto guide signs. But the internal exit tabs combined with the maximum sign height of 120 inches can sometimes create busy sign layouts.

[jakeroot]

I prefer internal exit tabs because they keep information within the sign to a minimum. I think of them as sort of a watchdog towards preventing busy signs. If you can't figure out how to fit everything into the sign, then you need to rethink the sign or move the sign to a different gantry where there's more room.

It would seem that the internal tabs combined with every sign being the same height would be the CAUSE of CA's squashed, busy signage.

I would agree with this.

California generally isn't prone to try and add too many extraneous destinations and street names onto guide signs. But the internal exit tabs combined with the maximum sign height of 120 inches can sometimes create busy sign layouts.

That's a good point, now that I think about it. Perhaps if they did it WSDOT style where the entire top 1/xx of the sign was the exit tab, that might help things look less busy.

From an "artists" point of view, I like California because, compared to many other states, their sign gantries don't have this silhouette:



They are instead nice and flat. Yeah, I know, aesthetics aren't key here, but that doesn't mean I can't complain about it.

[myosh_tino]

From an "artists" point of view, I like California because, compared to many other states, their sign gantries don't have this silhouette:



They are instead nice and flat. Yeah, I know, aesthetics aren't key here, but that doesn't mean I can't complain about it.

Just wanted to point out that not all California gantry silhouettes are "flat".  Generally speaking, 110 and 120 inch guide signs do extend above the top of the truss.

[jakeroot]

Just wanted to point out that not all California gantry silhouettes are "flat".  Generally speaking, 110 and 120 inch guide signs do extend above the top of the truss.

Yeah, they did away with the 120" gantry didn't they? Either way, as long as all the signs are the same height, I'm happy.

[jrouse]

What you saw on I-5 at CA-120 is, as far as I know, an aberration.  The reason why the exit number tabs have been placed in the main sign panel over the years is because Caltrans does not have a standard detail for mounting sign tabs on top of the truss.  This is because many of the sign trusses on the system don't meet the current AASHTO wind load standards, and so Caltrans didn't want to put together a detail that would further violate the standards.  The sign trusses can continue to be used but the sign panel area sizes cannot be increased.  Even though the current sign truss designs do meet the AASHTO wind load standards and are capable of handling tabs (and I think the full sign bridge pictured is one of them), Caltrans still has not developed a standard detail for mounting tabs. 

It is likely that these tabs were mounted using a special design.   This has been done in a few cases.


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[vdeane]

Just wanted to point out that not all California gantry silhouettes are "flat".  Generally speaking, 110 and 120 inch guide signs do extend above the top of the truss.

Yeah, they did away with the 120" gantry didn't they? Either way, as long as all the signs are the same height, I'm happy.

IMO the cluttering/empty space that can result from trying to make all the signs the same height is EXTREMELY ugly.  Meanwhile, signs that are different heights on the truss don't bother me at all.

What you saw on I-5 at CA-120 is, as far as I know, an aberration.

IMO it's every other sign in California that's an aberration.

The reason why the exit number tabs have been placed in the main sign panel over the years is because Caltrans does not have a standard detail for mounting sign tabs on top of the truss.

Doesn't Nevada use the same truss?  Take their detail.

The sign trusses can continue to be used but the sign panel area sizes cannot be increased.

In NY, when we replace signage, we usually replace the truss the signs are mounted on as well.  I assume this is one reason why.

[myosh_tino]

What you saw on I-5 at CA-120 is, as far as I know, an aberration.  The reason why the exit number tabs have been placed in the main sign panel over the years is because Caltrans does not have a standard detail for mounting sign tabs on top of the truss.  This is because many of the sign trusses on the system don't meet the current AASHTO wind load standards, and so Caltrans didn't want to put together a detail that would further violate the standards.  The sign trusses can continue to be used but the sign panel area sizes cannot be increased.  Even though the current sign truss designs do meet the AASHTO wind load standards and are capable of handling tabs (and I think the full sign bridge pictured is one of them), Caltrans still has not developed a standard detail for mounting tabs. 

It is likely that these tabs were mounted using a special design.   This has been done in a few cases.

Interesting.

So on the older trusses that already violate wind load standards by AASHTO, new signs cannot be taller than the ones they replace?  For example...

...would not be allowed if the truss already violates the wind load standards.

From what I could tell, it appears that these new signs with the external exit tabs were mounted on the existing trusses which, by my recollection, aren't new by any means.  I believe these trusses are at least 15 years old.  Here are photos of these two trusses from the AARoads Gallery taken in 2004...

[andy3175]

From what I could tell, it appears that these new signs with the external exit tabs were mounted on the existing trusses which, by my recollection, aren't new by any means.  I believe these trusses are at least 15 years old. 

My guess is that the first of those two trusses is even older than that, probably dating to the construction of the freeway. I say that because  both signs on the first truss are porcelain enamel, which was no longer used as a standard after say around 1972 or 1973. I doubt a new truss was placed with the old signs mounted after 1973. So the first truss is likely very old indeed, closer to 40 years old. I didn't take the time just now to review the bridge log to date the original construction of that segment of I-5, but early 1970s seems about right.

[myosh_tino]

Just remembered.  When the new Presidio Parkway opened in July, the news footage I saw included glimpses of the signs for the Marina Blvd exit and I could have sworn I saw an external exit tab on that sign as well.

[AndyMax25]

Just remembered.  When the new Presidio Parkway opened in July, the news footage I saw included glimpses of the signs for the Marina Blvd exit and I could have sworn I saw an external exit tab on that sign as well.

You are correct sir. It seems like there are 2 instances, both along the southbound side. The first just before the entrance to the second tunnel and the second inside the second tunnel.

Oddly, the first sign shows exit number 473 and the one in the tunnel shows 237.  The gore point sign also shows 237.  The route 101 document on Cal-NExUS shows "Marina Blvd (Left Exit)" to be 437.  What the heck is going on!!?? Can anyone confirm if these exit tabs have been changed?  Seems like they all should be 437.

The earlier exit for Route 1 south/19th St correctly shows exit 438.

[TheStranger]

Just remembered.  When the new Presidio Parkway opened in July, the news footage I saw included glimpses of the signs for the Marina Blvd exit and I could have sworn I saw an external exit tab on that sign as well.

You are correct sir. It seems like there are 2 instances, both along the southbound side. The first just before the entrance to the second tunnel and the second inside the second tunnel.

Oddly, the first sign shows exit number 473 and the one in the tunnel shows 237.  The gore point sign also shows 237.  The route 101 document on Cal-NExUS shows "Marina Blvd (Left Exit)" to be 437.  What the heck is going on!!?? Can anyone confirm if these exit tabs have been changed?  Seems like they all should be 437.

Probably a straight up typo!  Hopefully this'll be fixed soon. Marina Boulevard is no longer a left exit (as noted in the photo) but was from 1937 to the demolition of the old Doyle Drive.  (The Marina exit would have possibly also been incorporated into the never-constructed portion of 480 between Broadway and the Presidio, as the mainline lanes)

VERY surprised that there's no 101 shield in the second photo.  Is this the first all-text route sign on a California freeway in years?

[AndyMax25]

FYI I emailed Caltrans and the construction authority. I got a reply from the Presidio Parkway group stating "The contractor is aware of this issue and is investigating."

[pctech]

Do the newer mono-tube sign supports in CA meet the wind standards?  Does Caltrans plan to change out the sign supports over time?...even though it would cost $$$$$?
I've seen pictures of the same kind of sign supports in AZ. & NV. that CA. uses with exit tabs on top of the BGS.....are they actually a different design?

[roadfro]

^ I've got to think that they do. Nevada used monotube sign supports to mount their first real APL signs, which are HUGE. The standard truss wouldn't work with APLs. However, it seems (but I have no way to verify) that there would be less structural support against wind forces in the monotube design, especially with a large sign...

I have no idea whether Caltrans and NDOT use different monotube designs. I do believe, however, that NDOT's sign mounting is different. NDOT signs appear to be formed by a rigid steel frame (including exit tab) with sign panels riveted to the frame, then the frame is attached to the support structure. I think this negates the need for an exit tab mounting detail, but I'm not 100% certain.

[jrouse]

So on the older trusses that already violate wind load standards by AASHTO, new signs cannot be taller than the ones they replace?  For example...

...would not be allowed if the truss already violates the wind load standards.

That would be correct.

From what I could tell, it appears that these new signs with the external exit tabs were mounted on the existing trusses which, by my recollection, aren't new by any means.  I believe these trusses are at least 15 years old.  Here are photos of these two trusses from the AARoads Gallery taken in 2004...

Yes, you are correct, those are older trusses.  That was my bad.  There is a new truss mounted on the San Joaquin River bridge, and I got that one mixed up with the others.

You'll notice on the truss that carries the Mossdale Road G85 sign that the G83 sign for Route 120 is now smaller than the original panel.  I wonder if the panel size was reduced to keep the sign surface area consistent. 


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