Pushing the MUTCD envelope: arrow-per-lane diagrammatics

[roadfro]

I do think something had to be done with the multiple arrows and their "dancing"...in some cases, it becomes very hard to distinguish the intended meaning. That said, something could have been done to design the signs so they weren't so monstrously huge.

APL are catching on to a degree. Nevada has used them in a couple places already--this comes from a state where there was only one diagrammatic arrow prior to 2006 (and none prior to 1994). NDOT has used APLs, but not yet adopted the other new MUTCD standards for multilane exits at intermediate interchanges that were introduced simultaneously with APLs.

I wholeheartedly agree about the intermediate exit solution introduced by the MUTCD, and am glad NDOT stuck with the classic white arrow & only arrow approach (what I believe JN Winkler has termed the "Lunenfeld & Alexander" approach).

[Alex]

Question, when you have a diagrammatic sign such as this where both lanes remain through and only one turns off, does it the arrow-per-lane concept still apply?



Or would a sign replacement simply consist of separate panels, where one reads "LEFT EXIT" and the other with two down arrows. I have noted that in the Peoria area, many of the conventional guide signs were replaced with Clearview, but that the diagrammatical signs were left in place. The only exception I found thus far is this sign.

[J N Winkler]

I don't think OAPL signs as specified in the 2009 Manual will catch on in the US. I think state DOT's will be reluctant to use them because they are gross overkill. There is too much wasted space on the lower portion of the sign. This will require unreasonably huge signs, especially over very wide roadways.

I am afraid events have already given the lie to your suggestion that OAPL signs won't catch on.  Here is the current state of play with regard to OAPL signs, state-by-state, to the best of my knowledge based on signing plans I collect (Y = State DOT uses OAPL; NI = I have no information to indicate whether the state DOT uses OAPL; N = State DOT does not use OAPL or has a policy in place to ensure OAPL is not used):

HI  NI
AK  NI
WA  Y
OR  Y
CA  Y
NV  Y
AZ  N
ID  N
MT  NI
WY  NI
UT  Y
CO  NI
KS  Y
NM  NI
TX  NI
OK  Y
LA  NI
AR  Y
MO  Y
IA  NI
NE  NI
SD  Y
ND  NI
MN  NI (but different strategy used for option lanes at some interchanges)
WI  Y
IL  Y
IN  NI (but as for MN)
MI  Y
OH  NI
PA  Y
WV  NI
VA  Y
KY  Y
TN  NI
MS  Y
AL  NI (but stippled-arrow diagrammatics used extensively; also, as for MN)
GA  Y
FL  Y
SC  NI
NC  Y
MD  NI
DE  NI
NJ  NI
PA  Y
NY  NI
RI  NI
MA  NI
VT  NI
NH  NI
ME  NI

That is a total of 21 states with some confirmed usage of arrow-per-lane diagrammatics.  That is roughly the same number of states that were using Clearview at the same chronological remove (four years) from Clearview's grant of interim approval by FHWA.  Also, the ceiling is somewhat lower for arrow-per-lane diagrammatics since they are allowed only at option lanes, and there are bound to be a few states (ND and VT come to mind) which have no interchanges with option lanes.

I think it is totally valid to criticize OAPL signs for wasteful use of sign panel area, but I don't see this fact driving a groundswell of rebellion among state DOTs.  The main reason for this is that the MUTCD shall condition for the use of OAPL is very restricted:  only when (1) an option lane is present and (2) the interchange involves a split or the through route exits (TOTSO scenario).  I am sure there must be multiple states that have no interchanges meeting this very restrictive criterion.

I think state DOTs actually suffer more from the new restrictions applied to option lane signing in the 2009 MUTCD.  It now bans the use of stippled-arrow diagrammatics at interchanges with no option lane, the classic non-Lunenfeld & Alexander approach to signing service interchanges with option lanes (and its several variants as used in KS and AL), and "part-width" arrow-per-lane diagrammatics (which might otherwise be a useful option for service interchanges with option lanes).  The only option offered for signing option-lane exits in cases where an OAPL is not used involves arrows "hiding" the option lane.

I wouldn't be surprised if in the next MUTCD revision some years down the line, the FHWA modifies the design to a more reasonable format, something like that used on the German Autobahn system. They use similar arrows placed between and beside the legends, making much more efficient use of sign-space.

The basic design has already been rejigged.  Maximum arrow height on splits is 55" (compare to 22" height of downward-pointing arrow) and on exits is 66" (per SHSM 2012), down from 72" in the MUTCD dimensioning table.  There is also nothing in the MUTCD that dictates a top-down structure for legend blocks, which gives designers flexibility to accommodate very wide interchange throats.  We are restricted in how far we can go in adapting the German model, partly because the primary route number element on German signs is a cartouche in which the road number appears at a size smaller than the basic height of primary destination legend.

One approach that some state DOTs have tried, notably in MN, IN, and AL, is to locate a downward-pointing option lane arrow immediately underneath a vertical ruled line that separates the straight-ahead and right-hand destination blocks.  I do not think this approach has necessarily been ruled out by the 2009 MUTCD, though I believe it now requires a yellow "EXIT ONLY" panel for the arrow that represents the dropped lane.  One other approach that has been used elsewhere, notably in South Africa, is an "arrow block" diagrammatic with the straight-ahead and right-hand destinations arranged on either side of an arrow block in the middle of the sign.  This approach has the potential to make much more efficient use of sign panel area, but there is no support for it in the MUTCD.  It will also not help at interchanges where designers want to channel traffic that has not yet exited into the correct lanes for a split that is encountered immediately after the exit.  In the main Road-Related Illustrations thread, which has since been moved into its own board, I also floated the idea of a diagrammatic with separate arrow blocks showing the lane assignment scenario at each decision point in the sequence in which it is encountered (reading the sign from right to left).  This proved to be about as popular as Polish calculator logic.

Having said that, I will also re-state my opinion from earlier discussions that the FHWA created a problem where there wasn't one re: 2 arrows for different directions over an optional lane.  The solutions they have come up with including OAPL signing (at major xchanges) and single arrow advance signs with double arrow at the gore point (for intermediate xchanges) are so "flat-footed" that the cure is worse than the disease in my opinion.

This is a point which can be (and has been) debated.  We have OAPL because none of the existing options for signing lane drops with option lanes hits a home run.  Lunenfeld & Alexander studied the approaches that had been tried by the mid-1970's, and came up with the approach that has been diagrammed in the MUTCD from 1978 to 2003, and is now deprecated.  The "option lane hiding" approach comes from the Upchurch study (presented to GMITC around 2005) but its advantage over L&A and classic non-L&A was only incremental.  I am not aware of any testing that has been done on the Minnesota approach, while OAPL is supported by tachistoscope research only.  Option-lane signing is inherently a difficult problem, and I have seen the same churn among marginal design options repeated elsewhere, notably in Canada, the UK, and Spain.  I would venture to say that there seems to be less of it in Germany only because the Germans are not completely oriented toward intuitive design, probably believing that any unavoidable shortcomings in the signing system can be overcome by pushing periodic re-education out to holders of German driving licenses.

I wholeheartedly agree about the intermediate exit solution introduced by the MUTCD, and am glad NDOT stuck with the classic white arrow & only arrow approach (what I believe JN Winkler has termed the "Lunenfeld & Alexander" approach).

Actually, that is the classic non-Lunenfeld & Alexander approach.  L&A is basically the same, except the yellow "EXIT ONLY" panel is omitted (all arrows on the advance guide and exit direction signs are white on green), and a pull-through sign with downward-pointing arrows is always used, even at service interchanges.  L&A is what was diagrammed in the MUTCD from 1978 to 2003, although the MUTCD also permitted the classic non-L&A approach (it all depended on how you chose to interpret the term "multi-lane exit").

Straight L&A is very expensive to do if you have a lot of service interchanges with option lanes, so classic non-L&A became very popular in states like California that have many exits of precisely this type.

Question, when you have a diagrammatic sign such as this where both lanes remain through and only one turns off, does it the arrow-per-lane concept still apply?

No.  In fact diagrammatics of either type (arrow-per-lane or stippled-arrow) are not permitted.  Stippled-arrow diagrammatics used to be allowed at interchanges of this type, but as of MUTCD 2009 this is no longer true.

Or would a sign replacement simply consist of separate panels, where one reads "LEFT EXIT" and the other with two down arrows.

This is one option.  There is no requirement that downward-pointing arrows be used on the pull-through sign (the sign on right in this hypothetical scenario) at simple left exits, so those arrows could be omitted altogether.



Edit:  OH changed to IN (could not find a single example in 3,039 pages of Ohio DOT signing sheets), MI added as Y (I-69 west to Lansing/I-75, US 23 to Detroit and Saginaw).  Total count of OAPL-using states remains unchanged.

[myosh_tino]

I don't agree with your suggestion that OAPL signs won't catch on, because it is already factually untrue.  Here is the current state of play with regard to OAPL signs, state-by-state, to the best of my knowledge based on signing plans I collect (Y = State DOT uses OAPL; NI = I have no information to indicate whether the state DOT uses OAPL; N = State DOT does not use OAPL or has a policy in place to ensure OAPL is not used):

CA  Y

I'm not sure if I agree that California has embraced the OAPL signs.  As far as I know, Caltrans has not installed a typical arrow-per-lane sign on any of it's freeways yet although Jrouse, on the Pacific Southwest board, said that Caltrans may install one on northbound I-5 at the CA-1 exit south of Mission Viejo.

The only sign I can think of that even remotely resembles an arrow-per-lane sign is the one that JN Winkler has mentioned before on eastbound BL-80/US 50 at the BL-80/US 50/CA-99 interchange in Sacramento...



This sign was installed sometime in 2011 and while that was after the 2009 MUTCD was released, California didn't officially adopt the new MUTCD until 2012.  I suppose this could have been a Caltrans experiment with arrow-per-lane signage but this sign doesn't remotely come close to what a typical APL sign should look like.

With all of that said, if you still want to classify California as using OAPL signs, I think a "Y" with an asterisk is more appropriate.

[Alps]

NJ does not use these, although there have been no sign replacement projects lately.

[J N Winkler]

I'm not sure if I agree that California has embraced the OAPL signs.  As far as I know, Caltrans has not installed a typical arrow-per-lane sign on any of its freeways yet although Jrouse, on the Pacific Southwest board, said that Caltrans may install one on northbound I-5 at the CA-1 exit south of Mission Viejo.

The only sign I can think of that even remotely resembles an arrow-per-lane sign is the one that JN Winkler has mentioned before on eastbound BL-80/US 50 at the BL-80/US 50/CA-99 interchange in Sacramento...



This sign was installed sometime in 2011 and while that was after the 2009 MUTCD was released, California didn't officially adopt the new MUTCD until 2012.  I suppose this could have been a Caltrans experiment with arrow-per-lane signage but this sign doesn't remotely come close to what a typical APL sign should look like.

In addition to that particular sign (which I think may have been an in-kind replacement of an earlier sign), Caltrans has also experimented with the arrow-per-lane concept elsewhere--notably at the I-5/Calif. 99 split north of Sacramento.  This sign was at that location in 2002 and had a nonreflective (forest green) background, so it clearly pre-dates FHWA's unsuccessful first effort to introduce OAPLs in the NPRM that gave rise to the 2003 MUTCD.  It is true that none of these signs are vanilla MUTCD OAPLs, but then very few Caltrans signs look like their vanilla MUTCD equivalents, so I feel entitled to stretch a point.

NJ does not use these, although there have been no sign replacement projects lately.

The only transportation agency in NJ I have known to do pure sign replacements is the NJTA.  I have noticed that some agencies which never used to do pure sign replacements (other than by proposal book), such as Illinois DOT, have started to advertise pure sign replacements with accompanying plans that include sign panel detail sheets, but I don't know if NJDOT will participate in this trend anytime soon.

[NE2]

re FL: is that FDOT or only OOCEA? The latter has adopted APL and Clearview, but FDOT is sticking with FHWA fonts.

[jemacedo9]

New York does use APLs...both NYSDOT (there is one on MY 390 South approaching I-490 and one on I-590 South approaching I-390), and the Thruway in the Buffalo area.

[J N Winkler]

re FL: is that FDOT or only OOCEA? The latter has adopted APL and Clearview, but FDOT is sticking with FHWA fonts.

FDOT does use OAPLs--one example being the I-95/Turnpike split (currently being reworked under FPID 41546225201).

[Alex]

re FL: is that FDOT or only OOCEA? The latter has adopted APL and Clearview, but FDOT is sticking with FHWA fonts.

FDOT does use OAPLs--one example being the I-95/Turnpike split (currently being reworked under FPID 41546225201).

Per lane arrow signs are already in use in Jacksonville:

[SignBridge]

JNW, NYSDOT also has at least one OAPL sign on Long Island, on SR-25 at the interchange with I-495 (L.I. Expwy)

That Calif. style OAPL sign pictured up above for Routes 80/99, Reno/Fresno is perfect. A carbon copy of the arrows on some German Autobahn signs. It is intuitive and makes very efficient use of sign-space. Right on!

Anybody notice the error on that Florida sign for NAS Jax? On the exit number plaque, the word left is not black-on-yellow as specified in the MUTCD. How could they make a mistake like that on something so obvious?

[myosh_tino]

In addition to that particular sign (which I think may have been an in-kind replacement of an earlier sign), Caltrans has also experimented with the arrow-per-lane concept elsewhere--notably at the I-5/Calif. 99 split north of Sacramento.  This sign was at that location in 2002 and had a nonreflective (forest green) background, so it clearly pre-dates FHWA's unsuccessful first effort to introduce OAPLs in the NPRM that gave rise to the 2003 MUTCD.

I don't ever remember seeing any type of arrow-per-lane signs on northbound I-5 at the CA-99 split north of Sacramento.  A quick glance at Google Maps shows that the advance and exit direction signs on I-5 appear to be Caltrans-standard signs with down arrows used on the advance signs and diagonal arrows for the exit direction sign.

Because you mentioned an older forest green sign, I'm wondering if this is the sign you were thinking of?


If so, this is on westbound BL-80 at the BL-80/US 50/CA-99 interchange.  This appears to be a very old porcelain sign that's probably original to when the freeway was built.

That Calif. style OAPL sign pictured up above for Routes 80/99, Reno/Fresno is perfect. A carbon copy of the arrows on some German Autobahn signs. It is intuitive and makes very efficient use of sign-space. Right on!

In this case, the space was used very efficiently but what it the control cities were "Sacramento" and "Bakersfield" instead of "Reno" and "Fresno"?  Because the space between the arrows is fixed, control cities with longer names would not fit between the arrows.  The only solution is to either use a narrower font (Series D for example) or reduce the letter heights from 16/12 to, say, 13.3/10.

[pctech]

I like this design, think it works better where the highway diverges than the down facing arrows design.
This would work at the 1-10/12/59 (Louisiana) interchange on the westbound direction. The current labeling is confusing to someone who hasn't been through it.

Mark

[J N Winkler]

Because you mentioned an older forest green sign, I'm wondering if this is the sign you were thinking of?



If so, this is on westbound BL-80 at the BL-80/US 50/CA-99 interchange.  This appears to be a very old porcelain sign that's probably original to when the freeway was built.

I had all but finished composing a post to the effect that this could not be the sign and that the sign I saw definitely had to be on the northbound approach to the I-5/Calif. 99 split, when I remembered that I had photographed the sign in question.  Because I was not using a digital camera in 2002 (I did not purchase my first digital P&S until late spring 2003), I had to root through five crates of slide boxes to find the picture.  Eventually I did:  a transparency in slide box 424 (found in the fifth of five boxes checked) shows this sign:

Overhead arrow-per-lane diagrammatic on Calif. 99 at the Business 80 interchange in the northbound direction

The sign in your picture applies to exiting traffic in the opposite direction but the layout is otherwise very similar.

[agentsteel53]

those are button copy signs, not porcelain. 

[DRMan]

New Hampshire has OAPL signs on I-95 approaching Exit 4 in Portsmouth.

[SignBridge]

That southbound sign is horrible! Real California sign-salad. Conventional signing with standard down-arrows (if properly formatted) would have been more understandable. The northbound is at least a little better.

[countysigns]

There are a couple new OAPL BGS's on I-75 southbound nearing the I-475/US-23 split in Perrysburg.  Next time I go down to Bowling Green I'll have to take some pictures of them.

[NJRoadfan]

NJ does not use these, although there have been no sign replacement projects lately.

From another thread for others to see. NJ Turnpike Authority is using them. Is this sign a "correct" application? Exit 142C is an exit only lane drop as well.

[J N Winkler]

From another thread for others to see. NJ Turnpike Authority is using them. Is this sign a "correct" application? Exit 142C is an exit only lane drop as well.

No.  The reason it is not correct is not that the next exit is a simple lane drop, but rather that it fails to include arrows for the through lanes (as required in the 2009 MUTCD).  However, the NCUTCD subcommittee that deals with guide signs (GMITC) has proposed a revision to the MUTCD which would allow the arrows to be omitted for the through lanes under some circumstances.  This sign is similar to what GMITC has proposed.

[NJRoadfan]

While this installation may not be finished yet, I highly doubt they plan on mounting an additional sign there. If the NJ Turnpike Authority is determined to go MUTCD, they should at least get it right!

[SignBridge]

I agree with JN, and NJ. The sign is not fully compliant. Besides the arrows for the thru lanes, the "lane-drop" indications must begin with the advance sign, which was not done here. Shame on NJTA or NJDOT for not being a little sharper about that. (Not sure which agency controls that section of the Parkway)

If it's NJDOT, double shame on them. They have a long history of not properly signing lane-drops. Check out I-280 in Kearny at the exit for C.R.508, just before the Turnpike interchange.

BTW, JNW, what do NCUTCD and GMITC stand for?  I've never seen those abbreviations before.

[Scott5114]

Wait, where's there an APL in Oklahoma?

[roadman]

@SignBridge

Thanks for the detailed info and comments.

To add to your list, MassDOT is not presently installing OAPL signs on sign replacement projects, preferring to stick with stipple-headed diagrammatics (I've been told this practice has the blessing of the regional FHWA office, even for projects still in design).  However, on new projects with stipple-headed diagrammatic installations where OAPL would be appropriate per the MUTCD, it is now a requirement that the structures be designed to eventually accept the additional loading of the (much) larger OAPL panels.

[Alps]

So does anyone else notice that the 142C isn't aligned to the left edge, but the 142B is aligned to the right edge?