New MUTCD announced

[kphoger]

A normal person in 2023 isn't going to look at a map and say "this interchange has this number" and get bent out of shape if the same interchange has a different number in each direction. Indeed, they're not going to look at a map period, they're going to do whatever their gee pee ess tells them and will only care what the signs that they see as they're driving to their particular destination at the moment say.

Normal people still use the Rand McNally road atlas.  (Some of my best friends are normal.)

And if they want exit 25C to get where they're going, they will expect exit 25B to precede it and may be caught off guard if there is no 25B.

Heck, I'm a non-normal roadgeek, and that would catch me off-guard.

Meanwhile they won't notice or care if exit 25B in the opposite direction goes to a different place because they're not driving in the opposite direction so that isn't relevant to them.

They also won't notice or care if the opposite direction doesn't have an Exit #25B at all, I suppose.

It's going to come up with business advertising.  If the exit has a different number in each direction, the business can't just say "just off I-81 exit 32B" on their radio/TV/internet ads.

Maybe it's just a feature of the place I live, but I don't really hear things like "just off I-81 exit 32B" on the radio or TV or whatever.  About the only place I see that is on billboards, which can be tailor-cut for each direction (and hopefully the two don't get mixed up before installation, ha!).

But at any rate, as |PColumbus73| pointed out, the situation already exists at ParClo interchanges.  Take, for example, I-57 @ Vollmer Road in southern Cook County, IL.  If the nearby Shell station wanted to advertise its location by exit number—well, it's either #342 or #342A, depending on which direction you're traveling.  There are already interchanges with differential exit numbers, and apparently we've been OK with it all along.

I feel like mileage-based exit numbering is more intuitive than sequential ... I also think mileage based numbers is more adaptable with added or removed ramps.

This isn't really a discussion about mileage-based vs sequential exit numbering.  The real issue is that the current system is a combination of the two.  The numeric part of our exit numbers are mileage-based, but the alpha part of exit numbers are sequential.  Thus, US drivers operate with different expectations of how each part functions:  they fully expect there to be gaps between the numbers, but they likely don't expect there to be gaps between the letters.

I'm on the fence about that.  Honestly, in 2E-39, all the EXIT ONLY could be removed entirely with little to no ill effect.  But I do agree that, in order to be consistent with 2E-44, it should get an EXIT ONLY.

I totally agree. It should be for consistency and also to depict the lane movement options accurately.

Glad to know you're on the fence too!   

On "Line D", the further right interchange (25C) really should be 26 anyway.  Having the interchange numbered for a more distant milepost does not seem to be helpful for a driver to determine distances or accurately reporting their location.

Is that how your state does it?  It's my understanding that SOP is to round down if the crossroad passes over/under the highway before the next milepost.

On "Line D", the further right interchange (25C) really should be 26 anyway.  Having the interchange numbered for a more distant milepost does not seem to be helpful for a driver to determine distances or accurately reporting their location.

If it were to scale, sure. But in any case, that has always been the preferred MUTCD method of rounding. If you or your state prefers rounding to nearest milepost (e.g. rounding 25.8 to 26), then instead of line "D" from the diagram, consider a situation where "25 A" is at 24.6, "25 B" NB is at 24.8, and "25 C" NB is at 25.4 . You would have a similar issue there.

Here's a visual comparison of truncation vs rounding:

[ran4sh]

Is there anything that states "mile-based exits shall be used"? 

The 2009 MUTCD already contained a prohibition on the sequential exit system. But if you're asking about mile-based exit numbers versus no numbers at all, I'm not sure if freeways with un-numbered exits are compliant

It was a dig of the Metrication thread.

In that case, it's also the 2009 MUTCD that removed references to metric units - at some point FHWA or a higher level of the federal government decided that federal funding would no longer be used to change to metric or to incentivize states/agencies to do so

[jeffandnicole]

It's going to come up with business advertising.  If the exit has a different number in each direction, the business can't just say "just off I-81 exit 32B" on their radio/TV/internet ads.

This situation comes up currently, especially at partial cloverleafs, where an interchange with 2 exits in one direction will have different exit numbers (ie: 32A/B) than the other direction if that only has 1 exit (32). 

[Big John]

It's going to come up with business advertising.  If the exit has a different number in each direction, the business can't just say "just off I-81 exit 32B" on their radio/TV/internet ads.

This situation comes up currently, especially at partial cloverleafs, where an interchange with 2 exits in one direction will have different exit numbers (ie: 32A/B) than the other direction if that only has 1 exit (32). 

Wisconsin would sign the 1 exit 32 A-B.

[jeffandnicole]

It's going to come up with business advertising.  If the exit has a different number in each direction, the business can't just say "just off I-81 exit 32B" on their radio/TV/internet ads.

This situation comes up currently, especially at partial cloverleafs, where an interchange with 2 exits in one direction will have different exit numbers (ie: 32A/B) than the other direction if that only has 1 exit (32). 

Wisconsin would sign the 1 exit 32 A-B.

NJDOT has at least one like this:  Exit 2B/C on I-295 NB. But that's an abnormally compared to most of the rest of the state. 

[vdeane]

One interesting thing I just thought of is how some sequential states went even further, using numbers to make sure that not only did each interchange have a unique exit number, but that each exit number also had a unique interchange.  So if you had a pair of half-interchanges, one for each direction, they would each get separate numbers.  This is actually how the discrepancy in exit numbers between the Hutchinson River Parkway and the Merritt Parkway at the NY/CT line first occurred.  NY's original sequential numbers used one exit number per general interchange, even if the ramps went to different roads.  At some point, NY decided it didn't like that, so it renumbers to give such ramps separate numbers.  CT didn't.  Of course, now those ramps have the same number again, since minimizing alphabet soup took priority over giving them separate numbers when NY renumbered the road to mile-based.

Then I start thinking, what if I was writing up directions for someone not familiar with the area.  They're not going to care. I could write up "Going North, Take Exit 23A, then turn Right onto Route 5 East..." and "Going South, Take Exit 23B, then turn Left onto Route 5 East..." and if they're obeying the correct directions, they'll still take the correct exit and make the proper turn.

I feel like mileage-based exit numbering is more intuitive than sequential. I see we've been using standard diamond and half-diamond interchanges as examples for/against mileage based numbers, but how about parclos, with two ramps from one direction and one from the other, or other complicated interchanges? Using the logic that every exit should have the same number, then if I-90 East has one exit at Exit 25A, and I-90 West has two exits at Exit 25A, then how does that work? Are both westbound exits 25A?

I think it's overthinking it a little that because one direction is Exit 25A, then the other direction has to be Exit 25A as well. Using A, B, C... is just a suffix. I can understand that if I'm approaching Exit 25A, that means there are more than one exit within MM 25. With sequential exits, Exit 25 might be two miles from Exit 25A and then another 15 miles from Exit 26.

I also think mileage based numbers is more adaptable with added or removed ramps.

I don't think anyone was arguing against mile-based exit numbering itself, just this hare-brained idea that an interchange could get different exit numbers in each direction in the case of multiple interchanges in a mile with half-interchanges thrown in.  Sure, for a parclo, it's "just a suffix" because it's one interchange, but what about completely separate ones that just happen to be within the same two mileposts?

On "Line D", the further right interchange (25C) really should be 26 anyway.  Having the interchange numbered for a more distant milepost does not seem to be helpful for a driver to determine distances or accurately reporting their location.

If you want to be a purist, yes, however in practice more often than not exit numbers are assigned by always rounding down - so any exit from MM 25.00 to 25.99 gets numbered 25.

As far as the specific policy on assigning numbers, I can see where neither option in this situation is necessarily perfectly desirable. Having 25A and 25C with no 25B might trip people up, and so might having 25B go different places westbound vs. eastbound.

I do wonder though if this isn't one of those things where while we as roadgeeks will likely be more bothered by the latter, someone normal may actually be more bothered by the former, especially if they're unfamiliar with the area (which is who signs are primarily designed for). A normal person in 2023 isn't going to look at a map and say "this interchange has this number" and get bent out of shape if the same interchange has a different number in each direction. Indeed, they're not going to look at a map period, they're going to do whatever their gee pee ess tells them and will only care what the signs that they see as they're driving to their particular destination at the moment say. And if they want exit 25C to get where they're going, they will expect exit 25B to precede it and may be caught off guard if there is no 25B. Meanwhile they won't notice or care if exit 25B in the opposite direction goes to a different place because they're not driving in the opposite direction so that isn't relevant to them.

It's stupid and I hate it, but I see the reasoning. Normal people are stupid and I hate them, I guess. 🤷

I didn't even think about the mapping side.  How on Earth is Rand McNally supposed to handle this?

Incidentally, I really hate people who don't bother to look into where they're going and just rely on GPS.  What if the GPS is wrong or malfunctions?  Or the directions come too fast for you to react if you have no clue where you're going?

A couple months back, me and a few people from Main Office were heading to a meeting down in Kingston, and on the Thruway the driver asked "has anyone put this into GPS yet so we know where we're going?".  I was horrified, but everyone else seemed to think this was normal.  When we got into Kingston, we got to this roundabout, we ended up taking the wrong leg, because there's nothing a GPS can do to prepare you for a roundabout where your "turn" is actually straight.  Only looking at a map (and preferably street view too) will tell you that.  I knew about it... but nobody else did, and only my immediate co-workers aren't thrown by how much I know, so me knowing about it did jack shit in the moment.  The person who was driving then spent the whole day ranting about the roundabout.

It's going to come up with business advertising.  If the exit has a different number in each direction, the business can't just say "just off I-81 exit 32B" on their radio/TV/internet ads.

This situation comes up currently, especially at partial cloverleafs, where an interchange with 2 exits in one direction will have different exit numbers (ie: 32A/B) than the other direction if that only has 1 exit (32). 

In this case, it's one interchange, though.    Such would often get shortened to "exit 32" where I live even if heading the direction that has the A/B ramps.  Not so on what the MUTCD is recommending now...

[lordsutch]

GDOT jumped the gun a little bit; at exit 101 of I-75 they had already installed a yellow "EV Charging" tab a few weeks ago on the logo for the Pilot travel center that has EVgo/Ultium chargers at the interchange, as seen in Figure 2J-4.

The EV charging category is for businesses that are not gas stations. Because the MUTCD/FHWA have decided that a business that offers EV charging without gasoline, does not qualify for the "gas" sign. Gas stations that have EV charging can still be shown on the "gas" sign and be in compliance with the MUTCD.

Right; my point is that the EV CHARGING tab on gas signs wasn't legally permitted until the 11th Edition was finalized, but GDOT had already posted a sign using the tab.

[Duke87]

Maybe it's just a feature of the place I live, but I don't really hear things like "just off I-81 exit 32B" on the radio or TV or whatever.  About the only place I see that is on billboards, which can be tailor-cut for each direction (and hopefully the two don't get mixed up before installation, ha!).

It is a feature of where you live, yes. People in most of the northeast navigate by exit number and it's very common even in casual conversation to talk about things like "the McDonald's by exit 9". This is also part of why the northeast has the last holdouts for converting to mile-based numbering: since people are used to using exit numbers as landmarks, changing them for any reason causes a lot of confusion.

One interesting thing I just thought of is how some sequential states went even further, using numbers to make sure that not only did each interchange have a unique exit number, but that each exit number also had a unique interchange.  So if you had a pair of half-interchanges, one for each direction, they would each get separate numbers.  This is actually how the discrepancy in exit numbers between the Hutchinson River Parkway and the Merritt Parkway at the NY/CT line first occurred.  NY's original sequential numbers used one exit number per general interchange, even if the ramps went to different roads.  At some point, NY decided it didn't like that, so it renumbers to give such ramps separate numbers.  CT didn't.  Of course, now those ramps have the same number again, since minimizing alphabet soup took priority over giving them separate numbers when NY renumbered the road to mile-based.

Well, New York also did exactly what the 2023 MUTCD now stipulates with this, even though the project predates it. Rhode Island's mile-based conversion was done this way too (look at I-195).

The key thing is that this idea of "letter suffixes must only appear in unbroken sequence" didn't suddenly magic itself into existence for the 2023 MUTCD. It was already the prevailing opinion of transportation officials that skipping letters or having A with no B was bad, and it was already driving decisionmaking before it was officially codified. What I am curious to know is if there is any research supporting this or if it's just groupthink running on vibes.

[freebrickproductions]

In discussing exit number oddities, Exit 334 on I-65 in Alabama is entirely south of Milepost 334. In fact, it's actually right about Milepost 333, at least going northbound. I have no idea why 334 was chosen as the number, unless it dates back to when I-65 wasn't complete to Mobile, and ALDOT thought it'd be one mile longer than it wound-up being.

Similarly, I-565's Exit 2 is located entirely west of Milepost 2, with Mooresville Road crossing I-565 itself at about Milepost 1.3, per the signage, with the ramp from I-565 Eastbound splitting off at Milepost 1. The interchange with I-65 is also similarly signed as Exit 1, despite being the official start of I-565.
My only guess for this is that, when I-565 was built, ALDOT didn't sign Exit 0s with tabs. However, as I-565 Eastbound has two different ramps to I-65, they needed some way to delineate between the two, so the interchange for I-65 became I-565's Exit 1, so I-565 eastbound could have A and B ramps, while Mooresville Road was given Exit 2 to make it clearer that it wasn't part of the interchange with I-65. Given that ALDOT now signs Exit 0s, maybe they should bump them down by one.

[ran4sh]

Alabama has used exit 0 for a long time though. I remember going from North GA to the MS Gulf Coast and seeing both the south end of I-85 and the south end of I-65 posted as exit 0. This would have been in the early 90s

[ran4sh]

GDOT jumped the gun a little bit; at exit 101 of I-75 they had already installed a yellow "EV Charging" tab a few weeks ago on the logo for the Pilot travel center that has EVgo/Ultium chargers at the interchange, as seen in Figure 2J-4.

The EV charging category is for businesses that are not gas stations. Because the MUTCD/FHWA have decided that a business that offers EV charging without gasoline, does not qualify for the "gas" sign. Gas stations that have EV charging can still be shown on the "gas" sign and be in compliance with the MUTCD.

Right; my point is that the EV CHARGING tab on gas signs wasn't legally permitted until the 11th Edition was finalized, but GDOT had already posted a sign using the tab.

Yes it was? It's not a symbol being used.

2009 edition - Section 2J.03, paragraph 5

"A portion of a logo sign panel may be used to display a supplemental message horizontally along the bottom of the logo sign panel, provided that the message displays essential motorist information"

"EV charging" displayed as such supplemental message, is compliant.

Paragraph 10 "Typical supplemental messages might include DIESEL, 24 HOURS, CLOSED and the day of the week when the facility is closed, ALTERNATIVE FUELS (see Section 2I.03), and RV ACCESS"

EV uses an alternative fuel

[freebrickproductions]

Alabama has used exit 0 for a long time though. I remember going from North GA to the MS Gulf Coast and seeing both the south end of I-85 and the south end of I-65 posted as exit 0. This would have been in the early 90s

When I was younger (2000s/early to mid-2010s), the south end of I-85 wasn't posted as Exit 0, and did not have a signed Exit number at all. Checking Street View, the signage did not have Exit 0 posted until sometime after 2017:
https://www.google.com/maps/@32.3678168,-86.3121473,3a,76y,265.36h,92.67t/data=!3m7!1e1!3m5!1s7V9v9H1QtaPmZAHWRsVE4A!2e0!5s20170401T000000!7i13312!8i6656?entry=ttu
https://www.google.com/maps/@32.3676392,-86.3186067,3a,43y,260.34h,94.22t/data=!3m7!1e1!3m5!1sBz5NKkuA-FyGISeaT6V5sg!2e0!5s20160801T000000!7i13312!8i6656?entry=ttu

It appears Mobile has always had the south end of I-65 posted as Exit 0 on the overheads, but the two overheads before the I-10 interchange still lack any exit tabs. However, I rarely ever went to/through Mobile when I was younger (my family preferred going to Florida to visit the Gulf and taking US 231 out of Montgomery to get there), so I have straight-up no memories of the south end of I-65. In fact, prior to visiting last spring, I think my only other visit to that area was when I passed through on a trip to Dauphin Island when I was in elementary school.

[vdeane]

Maybe it's just a feature of the place I live, but I don't really hear things like "just off I-81 exit 32B" on the radio or TV or whatever.  About the only place I see that is on billboards, which can be tailor-cut for each direction (and hopefully the two don't get mixed up before installation, ha!).

It is a feature of where you live, yes. People in most of the northeast navigate by exit number and it's very common even in casual conversation to talk about things like "the McDonald's by exit 9". This is also part of why the northeast has the last holdouts for converting to mile-based numbering: since people are used to using exit numbers as landmarks, changing them for any reason causes a lot of confusion.

One interesting thing I just thought of is how some sequential states went even further, using numbers to make sure that not only did each interchange have a unique exit number, but that each exit number also had a unique interchange.  So if you had a pair of half-interchanges, one for each direction, they would each get separate numbers.  This is actually how the discrepancy in exit numbers between the Hutchinson River Parkway and the Merritt Parkway at the NY/CT line first occurred.  NY's original sequential numbers used one exit number per general interchange, even if the ramps went to different roads.  At some point, NY decided it didn't like that, so it renumbers to give such ramps separate numbers.  CT didn't.  Of course, now those ramps have the same number again, since minimizing alphabet soup took priority over giving them separate numbers when NY renumbered the road to mile-based.

Well, New York also did exactly what the 2023 MUTCD now stipulates with this, even though the project predates it. Rhode Island's mile-based conversion was done this way too (look at I-195).

The key thing is that this idea of "letter suffixes must only appear in unbroken sequence" didn't suddenly magic itself into existence for the 2023 MUTCD. It was already the prevailing opinion of transportation officials that skipping letters or having A with no B was bad, and it was already driving decisionmaking before it was officially codified. What I am curious to know is if there is any research supporting this or if it's just groupthink running on vibes.

The Hutch doesn't really have any examples of a single exit having two different numbers, though (aside from some not-updated signs at the CT border).  The closest is the NY 120 exit, 16B NB, 16 SB, but that situation isn't really unusual in a part of the country where one side of an exit being split by direction and the other side not is routine (even though that isn't the reason for it here).  Someone going SB looking for 16B would probably clue in to having to take 16 (especially if the rest of the state finally converts, and stuff like the 21/21B/21A/22 sequence on the Thruway goes away).

I suppose EB 1A/WB 1D on I-195 could count.  I didn't really think of them as such, but they are indeed signed similarly other than the number.  I wonder if the rule exists in part to reduce the number of letters used.  RIDOT certainly uses it for that.

[JoePCool14]

GDOT jumped the gun a little bit; at exit 101 of I-75 they had already installed a yellow "EV Charging" tab a few weeks ago on the logo for the Pilot travel center that has EVgo/Ultium chargers at the interchange, as seen in Figure 2J-4.

The EV charging category is for businesses that are not gas stations. Because the MUTCD/FHWA have decided that a business that offers EV charging without gasoline, does not qualify for the "gas" sign. Gas stations that have EV charging can still be shown on the "gas" sign and be in compliance with the MUTCD.

Right; my point is that the EV CHARGING tab on gas signs wasn't legally permitted until the 11th Edition was finalized, but GDOT had already posted a sign using the tab.

Yes it was? It's not a symbol being used.

2009 edition - Section 2J.03, paragraph 5

"A portion of a logo sign panel may be used to display a supplemental message horizontally along the bottom of the logo sign panel, provided that the message displays essential motorist information"

"EV charging" displayed as such supplemental message, is compliant.

Paragraph 10 "Typical supplemental messages might include DIESEL, 24 HOURS, CLOSED and the day of the week when the facility is closed, ALTERNATIVE FUELS (see Section 2I.03), and RV ACCESS"

EV uses an alternative fuel

Yes. That was previously an option, and still is. What I meant is that we have a new major category of permissible service signs, that being EV CHARGING. That brings the approved list to ATTRACTION, GAS, FOOD, LODGING, and EV CHARGING.

Basically, Tesla could apply to have supercharger locations on their own service sign category.

[Mergingtraffic]

I'm still amazed at how many posts are about exit numbers.

[Brandon]

A normal person in 2023 isn't going to look at a map and say "this interchange has this number" and get bent out of shape if the same interchange has a different number in each direction. Indeed, they're not going to look at a map period, they're going to do whatever their gee pee ess tells them and will only care what the signs that they see as they're driving to their particular destination at the moment say.

Normal people still use the Rand McNally road atlas.  (Some of my best friends are normal.)

And if they want exit 25C to get where they're going, they will expect exit 25B to precede it and may be caught off guard if there is no 25B.

Heck, I'm a non-normal roadgeek, and that would catch me off-guard.

Meanwhile they won't notice or care if exit 25B in the opposite direction goes to a different place because they're not driving in the opposite direction so that isn't relevant to them.

They also won't notice or care if the opposite direction doesn't have an Exit #25B at all, I suppose.

I find they don't worry about it.  Here are real-life examples on I-355 for Ogden Avenue and I-88, and on I-88 for I-355.  As the Ogden Avenue interchange occurs within the I-88 interchange, and the I-88 interchange is spread out over about two to three miles, there are a multitude of exit numbers depending on direction.  Overview of interchange: https://maps.app.goo.gl/D3S8bxCGW9Ny6Seo9

* Exit 20A nb for I-88 on I-355, about mm19: https://maps.app.goo.gl/MfNDR4NWSAdqvKfY8
* Exit 20B nb, also about mm19 for Ogden Avenue: https://maps.app.goo.gl/3NPQnCv9R3wVz1bY7
I-88 gets Exit 20 as ISTHA typically uses the truncation method; however, this would put Exit 20 for I-88 before Exit 19 for Ogden Avenue, so you now have Exits 20A and 20B.
* Exits 20 and 22 for I-88 and Butterfield Road are on a c/d setup for southbound: https://maps.app.goo.gl/pp6aXHJ7gKxmmyX59
* Followed by Exit 19 for Ogden Avenue: https://maps.app.goo.gl/HfEzPNABboYjjZci9

Then we get to I-88.

* Exit 131 eb is for I-355 south (and Ogden Avenue): https://maps.app.goo.gl/paoyUm9gWncxoDZ2A
* Then Exit 132 eb is for I-355 north: https://maps.app.goo.gl/USstX7NaRZCsNVzs7
* But, on wb I-88, it's Exit 131A and 131B for I-355 south and north, respectively: https://maps.app.goo.gl/PBMQ5GvK217gdB9A8
Never mind that this is at mm133 as I-355 crosses I-88 at mm131.

[jzn110]

On Page 350, cities of Brookfield and Green Bay changed to fictional cities of Somerset and Bay City.

Bay City, MI, would like a word.

[Big John]

On Page 350, cities of Brookfield and Green Bay changed to fictional cities of Somerset and Bay City.

Bay City, MI, would like a word.

It was listed as a control city for I-43.

[ran4sh]

The location of the cross road, not the ramp, is what the exit number is supposed to be based on

[on_wisconsin]

On Page 350, cities of Brookfield and Green Bay changed to fictional cities of Somerset and Bay City.

Bay City, MI, would like a word.

As would Somerset, WI...

[jeffandnicole]

I'm still amazed at how many posts are about exit numbers.

Because, no matter what, they should exist at nearly every exit on interstate highways. 

Some exits don't have route numbers.  Some don't have destinations or control cities.  But just about every exit has an exit number. 

[Quillz]

I'm still amazed at how many posts are about exit numbers.

Because, no matter what, they should exist at nearly every exit on interstate highways. 

Some exits don't have route numbers.  Some don't have destinations or control cities.  But just about every exit has an exit number. 

This reminds me: after all these years, there are still no exit numbers on the freeway alignment of CA-33 between Ventura and Casitas Springs. One of the few places in the state where this is still not a thing.

[KCRoadFan]

Way back when I looked at a past edition of the MUTCD, the thing I remember most was looking at the signs depicted in the "Freeway & Expressway Guide Signs" section (Chapter 2E), and about how the highways and town names shown on the various signs were a mixture of real and fake. Having just looked at that chapter in the latest edition, I wonder: of the sample guide signs - and sets of signs - shown in that chapter of the MUTCD, how many of them either (1) are based on real signs but with the roads and/or town names changed, or (2) have real town or road names, such that they could plausibly appear at some actual location, but some of the details have been tweaked? A couple of sample signs in the latter category come to mind: first, on page 314, there is an Interchange Sequence Sign that could have, at one point, appeared on the 110 freeway in Los Angeles just south of Exposition Boulevard; before 1983, the LA street that is now MLK Boulevard was known as Santa Barbara Avenue. Another one that I thought about is the distance sign for "I-52 East" on page 336, one which could theoretically appear on US 41 just north of I-70 in Terre Haute, Indiana, if not for the fact that (1) Veedersburg is misspelled as "Vedersburg" and (2) the distance figures are somewhat off, as it's about 55 miles to Veedersburg and 190 to Chicago heading north on US 41 from the Terre Haute exit, as opposed to 40 and 100.

Meanwhile, the sign assembly depicted on page 330, depicting Waltham and Weston, is an example of the first category, it being more-or-less a replica of the exit for US 20 on I-95/Route 128 in the Boston area, albeit with the route number and exit number changed and the directions reversed. (Coincidentally, the real Route 16 isn't far away from the actual interchange; however, Massachusetts uses squares, not circles, to mark their state highways.)

Aside from the above examples, are there any other guide signs in MUTCD Chapter 2E that are based off real signs but with one or more of the elements changed? If so, where would the originals be?

[ran4sh]

There are several which are probably based on real conditions, for various reasons.

For example, this isn't chapter 2E, but figure 2G-16 (associated with section 2G.15 ) pretty much exists because of the results of the investigation of the 2007 bus crash on I-75 in Atlanta (the investigators concluded that the bus driver likely thought that staying on the left was the through route of the HOV lane rather than an exit). In this edition the signs have Houston-area names/routes, but in previous editions I think different examples were used.

And figure 2G-28 is just a modification of 2G-16 for express toll lanes instead of HOV lanes.

[J N Winkler]

Way back when I looked at a past edition of the MUTCD, the thing I remember most was looking at the signs depicted in the "Freeway & Expressway Guide Signs" section (Chapter 2E), and about how the highways and town names shown on the various signs were a mixture of real and fake. Having just looked at that chapter in the latest edition, I wonder: of the sample guide signs - and sets of signs - shown in that chapter of the MUTCD, how many of them either (1) are based on real signs but with the roads and/or town names changed, or (2) have real town or road names, such that they could plausibly appear at some actual location, but some of the details have been tweaked? A couple of sample signs in the latter category come to mind: first, on page 314, there is an Interchange Sequence Sign that could have, at one point, appeared on the 110 freeway in Los Angeles just south of Exposition Boulevard; before 1983, the LA street that is now MLK Boulevard was known as Santa Barbara Avenue.

Various versions of that sign sketch have been in the MUTCD for decades.  The original Caltrans sign spec from 1957 called for white letters on black background and distances in miles and underlined tenths.



For that matter, a carbon copy of the original sign (with Santa Barbara Ave. updated to its current name) still exists on the southbound Harbor Freeway:



When stippled-arrow diagrammatics were added to the MUTCD and Standard Highway Signs in 1978 (if memory serves), the example sign for a split with I-270/Frederick on one side and I-495/Baltimore on the other was based on an actual sign installed on the Capital Beltway as part of the Mast and Kolsrud study in the late 1960's/early 1970's.  However, the real-life sign referenced I-70S since the redesignation to I-270 had not yet happened.  A number of stippled-arrow diagrammatics for service interchanges were also installed on this segment of the Beltway and were still standing as late as the mid-1990's.  However, signs to this general design were not added to the MUTCD, probably because they were not found to be effective, and the original prototypes are now long gone.  Each generally had a thick arrow (sometimes curved, sometimes not) with lane-line stippling running up the left side, with smaller arrows branching off of it to represent the exiting movements, similar to this not-quite-compliant example at the bottom end of the US 285 expressway in Santa Fe, New Mexico:



Other examples are based on real signs but nevertheless refer to fictitious locations, because the signs in question were test installations on a closed track.  For example, a number of illustrations have traditionally referenced "Metropolis" and "Utopia":  the former was one of the destinations used in the 1958 study that fixed green as the background color for Interstate guide signs.  The test signs for that study were installed on a section of what is now the Baltimore-Washington Parkway that was driveable but not yet open to public travel.

Aside from the above examples, are there any other guide signs in MUTCD Chapter 2E that are based off real signs but with one or more of the elements changed? If so, where would the originals be?

Generally speaking, the longer a sign illustration has been in the MUTCD, the more likely it is to be based on a real-life example, either on a closed course or a road open to public travel.  Until roughly the mid-2000's, it was difficult to make pattern-accurate illustrations for the MUTCD--as an example, Caltrans sign specs from the 1950's were typically made by composing snippets of legend by hand (either on a scale model or on an actual sign), taking a photo on dupe film, printing the result, cutting it out with scissors, and gluing it in place on a sheet of paper to make a dupe master.

All of that original art was re-mastered using vector drawing software to compose the 2003 edition of the MUTCD, but the example destinations were left in place, probably because there was nothing to be gained from change for change's sake while new destinations might fool old-timers into thinking the underlying provisions had changed when they hadn't.

When a sign illustration accompanies a section added to the MUTCD after 2003, it is less likely to be based on a real-life example or even a test sign in a study.  Recent research into guide signing (such as the study that gave us APLs) has used tachistoscopes (where the sign images are computer-generated) rather than field installations; also, since it is now so much easier to produce sign illustrations in a vector drawing program, there is no longer any advantage to recycling already-existing art.