Gantry Style/Design Between The States

[TheArkansasRoadgeek]

Let me start off with Arkansas, we use a varying design (in terms of executeability), it is a butterfly style and I honestly think it's dated. I read a post on here about how our gantry design was stuck in the 80's, but to be honest I have seen the same design (referenced from photos) in other states to a degree (if not the same).

What is your favorite gantry assembly?

Do you like your state's setup or not?

Thanks!

[Brandon]

Personally, I'm fond of Michigan's squared off ones: https://goo.gl/maps/twqXWu6H3Qn
Although, they sometimes use a heavier looking one: https://goo.gl/maps/HYQb2fB37Tv
And cantilevers: https://goo.gl/maps/SRXAGJRyejD2

IDOT's are fairly bland, IMHO: https://goo.gl/maps/Z6XocrvgDBC2
And cantilevers: https://goo.gl/maps/Px6ZLPVAUTn
Although, some parts of the state (especially District 1) used these in the 80s and 90s: https://goo.gl/maps/G3kVJt4BJo92
Cantilevers: https://goo.gl/maps/4CLfTkPr5hk

ISTHA uses a different, and better, IMHO, style: https://goo.gl/maps/8w8Aw75XtxR2
Although they use the IDOT style for some signs (due to length, I think): https://goo.gl/maps/6D4WiVkPMXF2
Cantilevers: https://goo.gl/maps/E4gy1VQ7gbE2

[TheArkansasRoadgeek]

I have a liking for tubular assemblies. They seem way more modern than most states, but MoDOTs Silver Dollar City assemblies heading to (and from) the location look nice. I will also never understand the overuse of doghouse assemblies on the MO 76 Strip in Branson, like, damn! Every intersection has them.

[MCRoads]

Oklahoma uses an almost caltrans-type gantry, however they are starting to use tubular mono-tube gantries. honestly, I don't like the new ones. I wish they would use more aesthetically pleasing gantries... or at least paint them...

[TheArkansasRoadgeek]

Oklahoma uses an almost caltrans-type gantry, however they are starting to use tubular mono-tube gantries. honestly, I don't like the new ones. I wish they would use more aesthetically pleasing gantries... or at least paint them...

I've seen Oklahoma use Arkansas' style closer to the border. But, Oklahoma's tubular style is cool, and most states tend to follow suite with California. Despite the state's debt, they tend to lead the way in transportation development and innovation (Hint: Botts' Dots). Most states now use Botts' Dots or a similar style with the same function.

[roadman]

With the exception of the Big Dig monotubes, which were a standardized design (purely for aesthetic reasons) that proved to be horribly expensive and (IMO) poorly designed in regards to actual sign loading, Massachusetts practice has always been to give fabricators only general design guidance, and leave the actual support style they use up to them.  The final design calculations and drawings are then reviewed and approved by either in-house engineers or the designer of record for a specific project.  Only then, are the structures released for actual fabrication.

This practice seems to have worked out well from both a cost and durability standpoint, as only two support structures (both cantilevers) installed during the current generation (1980s to present) of sign replacements have failed as a result of overstress due to weather (one was an anchor bolt failure during a blizzard, and the other took a direct hit from a tornado).

[Scott5114]

As with the last thread we had on this subject, it's a good idea to review the different types of truss, as not all trusses are the same:


(The image I used in the last thread died, so I had to make my own.)

Examples from the field:

Oklahoma, Pratt (although note modified Warren on top and sides)



Kansas, box


Illinois, modified Warren


Illinois, Vierendeel

[TheArkansasRoadgeek]

As with the last thread we had on this subject, it's a good idea to review the different types of truss, as not all trusses are the same:


(The image I used in the last thread died, so I had to make my own.)

Examples from the field:

Oklahoma, Pratt (although note modified Warren on top and sides)



Kansas, box


Illinois, modified Warren


Illinois, Vierendeel

Arkansas also uses Howe on the I-430 bridge. But, thank you Scott for the reference! The point I was making, in regards to Arkansas, was that we seem to use either a variation between Box (in some fashion) and Howe (in another). To me both are dated.

[Scott5114]

Now for the opinion post: To me, a truss (of any design, but I like the KS box gantry most) is the best-looking option. The gantry has to be able to support the visual "weight" or the signs (note that this is not referring to supporting weight in the engineering sense, but the architectural design sense). In the example photos I posted, the Kansas one is the best example–the gantry's vertical height is proportionate to what you'd expect would be "needed" to support a sign panel of that size. The Oklahoma and Illinois ones are so deep that they overpower the sign panels and feel like overkill (and Oklahoma's newest trusses are even taller). On the other hand, monotubes are so thin that they feel too flimsy to hold up most average-sized panels (although I know there's engineering rigor that proves that they're not).

Here's an example of a Texas Pratt truss that almost feels too small for what it's holding up:

[TheArkansasRoadgeek]

I-430 Bridge Ganry, Pratt or Howe origins?

[csw]

Looks like Pratt to me.

[thenetwork]

I believe Colorado's older trusses and cantilevers are all Pratts.  Most newer trusses and cantilever replacements are monotubes.

[jakeroot]

WSDOT exclusively utilises a box-monotube gantry, like the one pictured below. This design is used for both partial- and full-width gantries. Often, the gantries are painted to match surroundings (like guardrails sometimes are). Brown, dark green and black are the most common colors besides unpainted, although the 705 in Tacoma has some painted a sort of peach color.



Formerly, the box truss was used for full-width gantries, and a narrow version with a single up-right mast was used for partial-width gantries. There are also gantries in Clark County (Vancouver) that are the traditional curved monotube design, but they weren't used for very long, and AFAICT were only used there.

[PHLBOS]

With the exception of the Big Dig monotubes, which were a standardized design (purely for aesthetic reasons) that proved to be horribly expensive and (IMO) poorly designed in regards to actual sign loading, Massachusetts practice has always been to give fabricators only general design guidance, and leave the actual support style they use up to them.  The final design calculations and drawings are then reviewed and approved by either in-house engineers or the designer of record for a specific project.  Only then, are the structures released for actual fabrication.

This practice seems to have worked out well from both a cost and durability standpoint, as only two support structures (both cantilevers) installed during the current generation (1980s to present) of sign replacements have failed as a result of overstress due to weather (one was an anchor bolt failure during a blizzard, and the other took a direct hit from a tornado).

On some recent installations; I've noticed three two-panel per cantilevered gantry setups: Two along I-95/MA 128 (southbound in Burlington at Exits 3B-A & northbound at Exits 19A-B-C in Needham), the other along I-90/Mass Pike westbound in Springfield (at Exit 4) which features a single pipe/tube cantilever.

[MCRoads]

WSDOT exclusively utilises a box-monotube gantry, like the one pictured below. This design is used for both partial- and full-width gantries. Often, the gantries are painted to match surroundings (like guardrails sometimes are). Brown, dark green and black are the most common colors besides unpainted, although the 705 in Tacoma has some painted a sort of peach color.



Formerly, the box truss was used for full-width gantries, and a narrow version with a single up-right mast was used for partial-width gantries. There are also gantries in Clark County (Vancouver) that are the traditional curved monotube design, but they weren't used for very long, and AFAICT were only used there.

see, if only OK would paint the gantries, then they would look good [better_{(ok, maybe not that much better, but its a start)}]!




Off topic!

WOW! are those vmses? do they display in color? are other citys doing this "German autobahn" type thing?

[Brandon]

As with the last thread we had on this subject, it's a good idea to review the different types of truss, as not all trusses are the same:


(The image I used in the last thread died, so I had to make my own.)

Examples from the field:

Illinois, modified Warren


Illinois, Vierendeel

IDOT uses the above.  ISTHA tends to prefer a triangular Warren truss.

The Chicago Skyway (for some reason) uses Monotubes.

[Brandon]

WSDOT exclusively utilises a box-monotube gantry, like the one pictured below. This design is used for both partial- and full-width gantries. Often, the gantries are painted to match surroundings (like guardrails sometimes are). Brown, dark green and black are the most common colors besides unpainted, although the 705 in Tacoma has some painted a sort of peach color.



Formerly, the box truss was used for full-width gantries, and a narrow version with a single up-right mast was used for partial-width gantries. There are also gantries in Clark County (Vancouver) that are the traditional curved monotube design, but they weren't used for very long, and AFAICT were only used there.

see, if only OK would paint the gantries, then they would look good [better_{(ok, maybe not that much better, but its a start)}]!




Off topic!

WOW! are those vmses? do they display in color? are other citys doing this "German autobahn" type thing?

ISTHA is using them along the Northwest/Jane Addams Tollway (I-90) from Elgin to O'Hare.

You can see one on Google Street View here, while the road was under construction: https://goo.gl/maps/e43zATjZkr22

Update (ISTHA's website was down this morning for some reason): https://www.illinoistollway.com/documents/20184/582259/SmartRoad+One+Pager.pdf/102f501d-e64b-4f80-8797-ecbb98a241c8
There's a far better photo at the top of the PDF showing the Smart Road gantry on I-90.

[TheArkansasRoadgeek]

Illinois, modified Warren

Those two signs could be a reality in North Little Rock (in some fashion). Now, whether it will be within my lifetime, that is to be determined... (Also I-49)

[roadman]

As a sidebar to this thread, which states have standard design plans for overhead sign supports/gantries, and which states allow the fabricators to choose the support/gantry design based on the span length/sign sizes/loading requirements/etc.?

MassDOT is generally in the latter category (if you don't count the Big Dig monotubes).

[Brandon]

As a sidebar to this thread, which states have standard design plans for overhead sign supports/gantries, and which states allow the fabricators to choose the support/gantry design based on the span length/sign sizes/loading requirements/etc.?

MassDOT is generally in the latter category (if you don't count the Big Dig monotubes).

IDOT*, MDOT (Michigan), and ISTHA are in the former category.  Every gantry is the same for them, regardless of where in the state it is.

*And that even includes the brown Vierendeel trusses IDOT used during the 1980s and 1990s.

[kphoger]

What is your favorite gantry assembly?

Cantilevered monotube, followed by Kansas-style box truss.

[Pink Jazz]

Texas seems to be somewhat varied, with the El Paso District and some districts bordering New Mexico using monotubes as standard, but with other districts mostly using trusses (although monotubes are occasionally used).

[Scott5114]

What is your favorite gantry assembly?

Cantilevered monotube, followed by Kansas-style box truss.

I'm in agreement here–the monotube cantilever is sleek but doesn't feel "flimsy" like the full-width monotubes due to me. And there's something I find very aesthetically pleasing about the Kansas box truss in particular–it feels complex and industrial, but not overpoweringly so, for some reason. (That being said, Kansas's Howe cantilevers are pretty good too, and pair well with the box trusses. KDOT just hits the sweet spot for me on gantry design, I guess.)

As a sidebar to this thread, which states have standard design plans for overhead sign supports/gantries, and which states allow the fabricators to choose the support/gantry design based on the span length/sign sizes/loading requirements/etc.?

MassDOT is generally in the latter category (if you don't count the Big Dig monotubes).

I think you'll find more states with standards than those that leave it up to the contractor. Most states I've been to have a standard design that can be identified throughout the state, with exceptions usually being limited to individual projects or regions.

[Henry]

Illinois, Vierendeel

I wonder if Baltimore copied this to make its own:

[hbelkins]

I have also seen that Chicago style posted here on I-95 in Philadelphia, and it was in extensive use in Charleston, WV, until a sign replacement project  claimed most of them. A few are still in use, but the brown metal mesh behind the signs that used to be used was removed.

Kentucky uses a unique style of side-mounted overhead, that I've heard some refer to as "erector set." I haven't seen this in any other state.

2017 Tennessee eclipse trip Day 2 - 039 by H.B. Elkins, on Flickr

2016 East End Bridge Trip Day 1 - 211 by H.B. Elkins, on Flickr