Level vs. Centered

[Henry]

When you see two or more overhead freeway signs, which one looks better? To give a better idea of it, here is an example of each:

Level (the bottoms of all signs line up on the same level)


Centered (the signs are centered on the gantry)

[7/8]

That first example doesn't seem the best since it's both level and centred. Here's one that's level but not centred (403/QEW in Burlington, ON).

I might have a slight preference for level since the arrows line up, but they both look fine to me.

[ran4sh]

I prefer what you call "level", and NC used to be consistent at aligning the bottom of multiple BGS on the same gantry, but some of their newer installations don't comply.

[jakeroot]

If there are arrows, I prefer level. Otherwise I'm fine with centering the signs.

Personally, I would rather everything the same height, with exceptions. So everything is both level and centered.

[J N Winkler]

I might have a slight preference for level since the arrows line up, but they both look fine to me.

I prefer level primarily for that reason.  It also keeps more of the sign within headlamp spill and usable observation angle for longer, though a few inches or even feet one way or the other doesn't matter that much.  Enforcing minimum clearance of 17 feet is the important consideration.

When I prepare sign mockups for display on this forum and there are multiple signs in a single exported image, I use a "gantry aligner" script to establish a consistent horizontal separation between each sign (regardless of arrow position on the signs themselves), with all signs bottom-aligned to each other.

[hbelkins]

If there are arrows, I prefer level. Otherwise I'm fine with centering the signs.

Personally, I would rather everything the same height, with exceptions. So everything is both level and centered.

How about level from the top? Does anyone do that?

I don't like wasted space, so if you have signs of the same height with different amounts of copy, you get wasted sheet metal. That's one reason I hate OAPL signs. They're much bigger and more expensive than they need to be.

[Dirt Roads]

As in the Burlington, Ontario example, it seems to me that most of the BGS cantilevers/sign bridges were set to level (bottom justified) when sign lighting was required due to poor reflectivity.  Most state DOTs also seemed to have been fixated on setting the signage and lighting at the minimum clearance (probably related to the poor reflectivity issue as well).  Over time, DOTs appear to have become more comfortable with sign visibility and have ratched up the overall height of the signs.  As a result, you can now design smaller structures and place the signs "centered" along the cantilever/bridge arm to minimize wind vibration across the structure.

[CtrlAltDel]

Personally, I would rather everything the same height, with exceptions. So everything is both level and centered.

I am in this camp as well.

[SkyPesos]

I prefer center.
Regarding level and centered signs, it either results in too much wasted space, or squeeze in too much information in a limited space from trying to keep the signs the same height. Centered only doesn't have that constraint.

[wanderer2575]

I prefer bottom-leveled because it was Michigan's practice and it's what I'm used to.  It has a neat, orderly look.  Now, especially on trichord gantries, a lot of newer Michigan signs look like they're just randomly thrown up; not even centered.

And while I'm generally not a fan of increasing blank space for the sake of getting multiple signs to match, I concede there's a point where bottom-leveling gets ridiculous.  For example...

[Tom958]

...there's a point where bottom-leveling gets ridiculous.  For example...

I concur wholeheartedly. Those North Carolina setups require too much vertical eye movement and thereby surely impair drivers' ability to comprehend the message. They shouldn't do it at all, much less pay extra for it.

[fillup420]

...there's a point where bottom-leveling gets ridiculous.  For example...

I concur wholeheartedly. Those North Carolina setups require too much vertical eye movement and thereby surely impair drivers' ability to comprehend the message. They shouldn't do it at all, much less pay extra for it.

I drive past this setup frequently, and it has always bugged me. Why not mount the biggest sign up higher, so the smaller ones aren't awkwardly lower than the gantry?

Side note, this is a rare and unique picture, due to the short-lived I-495 designation on the BGS, but an I-87 shield in the background.

[odditude]

in cases where there are arrows on the bottoms of signs, i prefer bottom-leveled. otherwise, i prefer centered.

that NC assembly would be much be much better centered, imo.

[ran4sh]

I have no issue with that NC example. The sign for the local street uses standard size text, while the sign for the Interstate uses larger than standard text, which is permitted in the MUTCD. Maybe they could remove one of the three destinations to make the sign smaller, but they don't have to. (And IMO I-440 west should have a control city, whether it's Oxford, Durham, etc)

The same assembly in a state like GA would have "wasted space" on the local street sign (Poole Rd), which some of y'all have complained about above.

[Scott5114]

The bottom edges of all signs should be level with the bottom member of the gantry.

Meanwhile, the practice of making all of the signs on a gantry the same vertical height is completely ass-backwards, so much so that the MUTCD actually bans it. To follow the MUTCD, you have to determine the panel size according to the size of the legend and nothing else, certainly not the sizes of other, unrelated signs that happen to be posted nearby. Obviously there will always be some amount of let for practicality's concern (e.g. rounding up to the next whole incremental panel size), but if you are determining panel size based on the sizes of other signs on the gantry you are putting form before function, which should never be allowed in a traffic engineering context.

[bing101]

When you see two or more overhead freeway signs, which one looks better? To give a better idea of it, here is an example of each:

Level (the bottoms of all signs line up on the same level)


Centered (the signs are centered on the gantry)

I like the signs when they are leveled.

[DrSmith]

I would assume from a structural point, you would want the signs centered. That way any wind load isn't stressing the structure in one direction over another.

[ran4sh]

I would assume from a structural point, you would want the signs centered. That way any wind load isn't stressing the structure in one direction over another.

That would probably be why NC centers the largest sign and lowers the remaining signs, rather than what was suggested in above posts that the large sign should be higher on the structure.

[Ned Weasel]

The bottom edges of all signs should be level with the bottom member of the gantry.

I was gonna say, "Tell that to MoDOT," but it looks like somebody already told them: https://goo.gl/maps/rPmVq8e1Mibo8bre8

Now let's see if they remember whenever this gets re-done: https://goo.gl/maps/H7iLEm8rwvaXssu18

Meanwhile, the practice of making all of the signs on a gantry the same vertical height is completely ass-backwards, so much so that the MUTCD actually bans it. To follow the MUTCD, you have to determine the panel size according to the size of the legend and nothing else, certainly not the sizes of other, unrelated signs that happen to be posted nearby. Obviously there will always be some amount of let for practicality's concern (e.g. rounding up to the next whole incremental panel size), but if you are determining panel size based on the sizes of other signs on the gantry you are putting form before function, which should never be allowed in a traffic engineering context.

What section of the MUTCD says that?  At least the MUTCD cares about not wasting sheet metal.  https://goo.gl/maps/WUiEDgg4fYj3kBho9

[jakeroot]

The bottom edges of all signs should be level with the bottom member of the gantry.

Maybe need a bit more explanation, but how would that work with gantries such as those used by WSDOT?

but if you are determining panel size based on the sizes of other signs on the gantry you are putting form before function, which should never be allowed in a traffic engineering context.

I feel like there are many scenarios where form absolutely plays a role in traffic engineering. Eg, intentionally restricting panel height may also encourage reduced message loading.

[ran4sh]

The bottom edges of all signs should be level with the bottom member of the gantry.

Maybe need a bit more explanation, but how would that work with gantries such as those used by WSDOT?

And that rule also wouldn't work with the gantries used in a lot of the East/Southeast. It's common for a sign to be 3x or 4x the height of the gantry, no way would they align the bottom of the sign to the bottom of the gantry.

but if you are determining panel size based on the sizes of other signs on the gantry you are putting form before function, which should never be allowed in a traffic engineering context.

I feel like there are many scenarios where form absolutely plays a role in traffic engineering. Eg, intentionally restricting panel height may also encourage reduced message loading.

That seems more like a hypothetical than anything. It's rare that an agency reduces message loading in order to fit a restricted height sign. CA certainly doesn't do that. And states that don't have restricted height signs simply make larger signs.

[jakeroot]

but if you are determining panel size based on the sizes of other signs on the gantry you are putting form before function, which should never be allowed in a traffic engineering context.

I feel like there are many scenarios where form absolutely plays a role in traffic engineering. Eg, intentionally restricting panel height may also encourage reduced message loading.

That seems more like a hypothetical than anything. It's rare that an agency reduces message loading in order to fit a restricted height sign. CA certainly doesn't do that. And states that don't have restricted height signs simply make larger signs.

It's primarily an incidental benefit: if you sign only the most relevant information, you probably don't need a huge sign.

Alternatively, why do we insist on stacking everything? Tall signs could be swapped for wider signs just by rearranging the shields to be to the left of the destination legend.

[roadfro]

The bottom edges of all signs should be level with the bottom member of the gantry.

Maybe need a bit more explanation, but how would that work with gantries such as those used by WSDOT?

My preference mirrors Scott's. I think overhead signs should be mounted so that the bottom of the sign is aligned with the bottom chord on the sign gantry, at least for installations that states that use larger trusses (such as the Pratt truss, which is the standard in Nevada and prevalent in much of California). This way, arrows at the bottom of the signs are on the same level and everything just looks better aesthetically.

However, for those states that use a style of truss with a shorter depth or use monopoles, centered tends to look better. For these mounting styles, and attempts to align the signs at a common level often look quite comical, like the example from I-440 posted upthread.

but if you are determining panel size based on the sizes of other signs on the gantry you are putting form before function, which should never be allowed in a traffic engineering context.

I tend to like having all panels on a gantry be the same height, as it looks a lot cleaner to me, and it seems like a bit less in eye movement making the panels easier to read. Granted, I'm a bit biased in this regard because this is the default in Nevada where I've lived my whole life.

Nevada's approach isn't as rigid as neighboring California. NDOT generally has all panels the same height, and sometimes this results in a modest increase in sign area for some signs. (For example, this advance sign for Oddie Blvd on US 395 south is taller than need be for the amount of text, due to the height of the adjacent I-80 advance sign.) But Nevada doesn't enforce same size signs when it would be an obnoxious waste of sign panel area (like this regular exit sign next to an APL on I-80 West), and sometimes will allow the signs to be different heights even when they could've easily been forced to same height (like the southbound Airport Connector to I-215 signage, although I think this was a Clark County project not directly overseen by NDOT).

[Scott5114]

Meanwhile, the practice of making all of the signs on a gantry the same vertical height is completely ass-backwards, so much so that the MUTCD actually bans it. To follow the MUTCD, you have to determine the panel size according to the size of the legend and nothing else, certainly not the sizes of other, unrelated signs that happen to be posted nearby. Obviously there will always be some amount of let for practicality's concern (e.g. rounding up to the next whole incremental panel size), but if you are determining panel size based on the sizes of other signs on the gantry you are putting form before function, which should never be allowed in a traffic engineering context.

What section of the MUTCD says that?  At least the MUTCD cares about not wasting sheet metal.  https://goo.gl/maps/WUiEDgg4fYj3kBho9

Section 2E.14, Size and Style of Letters and Signs:

Standard:
For all freeway and expressway signs that do not have a standardized design, the message dimensions shall be determined first, and the outside sign dimensions secondarily.

The same standard statement (which is quite lengthy) then goes into a discussion about text sizes and lowercase loop height (this statement is the source of the 3/4 error, incidentally), and then has a pointer to the next section, which discusses interline and margin spacing. Then there are about 5 tables of dimensions, including the lovely Table 2E-4 (which I refer to enough in my job that I have it posted to the wall by my desk), which set out the minimum letter sizes for freeway guide signs. Taken together, it's pretty clear that the intent is that the designer will use the letter size table to determine the size of the legend, then add the interline and edge line spacings to derive the correct panel size.

This is consistent with what is stated much more directly back in Section 2D.04 (applying to conventional-road guide signs):

Support:
For other guide signs, the legends are so variable that a standardized design or size is not appropriate. The sign size is determined primarily by the length of the message, and the size of lettering and spacing necessary for proper legibility.

There is a carve-out for particularly odd situations in Section 2E.14, as well:

Support:
A sign mounted over a particular roadway lane to which it applies might have to be limited in horizontal dimension to the width of the lane, so that another sign can be placed over an adjacent lane. The necessity to maintain proper vertical clearance might also place a further limitation on the size of the overhead sign and the legend that can be accommodated.

So basically, you can use this provision if you're physically constrained from doing so, like in perhaps a tunnel, or if you have unusually narrow lane widths. Note there is no allowance for "we think it looks nice if the panels are the same size."

Eg, intentionally restricting panel height may also encourage reduced message loading.

There is no need for that because the MUTCD directly addresses message loading separately from panel size. Section 2E.10:

Guidance:
01 No more than two destination names or street names should be displayed on any Advance Guide sign or Exit Direction sign. A city name and street name on the same sign should be avoided. Where two or three signs are placed on the same supports, destinations or names should be limited to one per sign, or to a total of three in the display. Sign legends should not exceed three lines of copy, exclusive of the exit number and action or distance information.

[ran4sh]

The bottom edges of all signs should be level with the bottom member of the gantry.

Maybe need a bit more explanation, but how would that work with gantries such as those used by WSDOT?

My preference mirrors Scott's. I think overhead signs should be mounted so that the bottom of the sign is aligned with the bottom chord on the sign gantry, at least for installations that states that use larger trusses (such as the Pratt truss, which is the standard in Nevada and prevalent in much of California). This way, arrows at the bottom of the signs are on the same level and everything just looks better aesthetically.

However, for those states that use a style of truss with a shorter depth or use monopoles, centered tends to look better. For these mounting styles, and attempts to align the signs at a common level often look quite comical, like the example from I-440 posted upthread.

but if you are determining panel size based on the sizes of other signs on the gantry you are putting form before function, which should never be allowed in a traffic engineering context.

I tend to like having all panels on a gantry be the same height, as it looks a lot cleaner to me, and it seems like a bit less in eye movement making the panels easier to read. Granted, I'm a bit biased in this regard because this is the default in Nevada where I've lived my whole life.

Nevada's approach isn't as rigid as neighboring California. NDOT generally has all panels the same height, and sometimes this results in a modest increase in sign area for some signs. (For example, this advance sign for Oddie Blvd on US 395 south is taller than need be for the amount of text, due to the height of the adjacent I-80 advance sign.) But Nevada doesn't enforce same size signs when it would be an obnoxious waste of sign panel area (like this regular exit sign next to an APL on I-80 West), and sometimes will allow the signs to be different heights even when they could've easily been forced to same height (like the southbound Airport Connector to I-215 signage, although I think this was a Clark County project not directly overseen by NDOT).

Interesting, does NV have any specific rules or guidelines to follow when deciding to make signs the same height or not?