NY - Sequential vs. Mile Based Exits

[Brandon]

Anyone having more exposure to mileage-based system than me: can you, from the top of your head, list at least 10-15 numbers along your most traveled route?

Easy (without even touching a map, all by memory):
I-55
250 - I-80, Iowa/Indiana
251 - IL-59, Shorewood/Plainfield
253 - US-52, Shorewood/Joliet
257 - US-30, Aurora/Joliet
261 - IL-126, Plainfield
263 - Weber Road
267 - IL-53, Romeoville/Bolingbrook
268 - Joliet Road (originally 269)
269 - I-355

I-355
12 - I-55, Chicago/St. Louis
13 - Boughton Road
15 - 75th Street
17 - 63rd Street/Hobson Road
18 - Maple Avenue
20A - I-88, Aurora/Chicago (northbound only)
20B - US-34, Ogden Avenue (northbound only)
19 - US-34, Ogden Avenue (southbound only)
20 - I-88, Chicago/Aurora (southbound only)
22 - IL-56, Butterfield Road
24 - IL-38, Roosevelt Road
27 - IL-64, North Avenue
29 - Army Trail Road
31 - US-20, Lake Street
I-290 (unnumbered, but should be 32)

I-290
7 - I-355, Joliet
5 - IL-390
4 - Biesterfield Road
1B - IL-72, Higgins Road/Woodfield Road/IL-58, Golf Road (northbound only)

Any more, from lesser used freeways and tollways?

[SignBridge]

Empirestate, I believe the Illinois Tollways only have barrier tolls so the duplicate exit numbers may not interfere with tollkeeping records. But if you had duplicate exit numbers on the NY Thruway, how would the controlled toll-ticket system know which of the two exits with the same number you entered from?

Hmmm.........Maybe the toll system would record them with the exit number and the route number. So for instance, Exit-4 would be 87-4 or 90-4 on the toll record. That might work.

[cl94]

When I was in Columbus, I had most of the exit numbers on in the area memorized. Forgot most of them after not being there for 10 years. That being said I can remember more than 10...

I-70:
99: I-71 South/SR 315
100A-B: US 23/33
101A: I-71
101B: 18th Street
102: Miller Ave/Kelton Ave
103A: Main St
103B: US 33/Livingston Ave/Alum Creek Drive
104A: US 33 EB
104B: James Rd

I-71:
104: SR 104
121: Polaris Parkway

I-270
20: Sawmill Rd
22: SR 315
23: US 23 north side
26: I-71 north side
27: Cleveland Ave
29: SR 3 north side
30: SR 161 east side
32: Morse Rd
33: Easton Way
35: I-670/US 62

[Jim]

I know that when I spent a year in Albuquerque, I got to know the area's exit numbers on I-25 and I-40 very well.  Now 14 years later, I don't remember them. 

Even averaging just a couple trips a year on the roads, I am sure I could name 12-15 numbers right now, probably more if I only need to get within 1 or 2 miles, on I-75 in Florida, and quite a few numbers on I-95 in the Carolinas and Georgia.

[Brandon]

Empirestate, I believe the Illinois Tollways only have barrier tolls so the duplicate exit numbers may not interfere with tollkeeping records. But if you had duplicate exit numbers on the NY Thruway, how would the controlled toll-ticket system know which of the two exits with the same number you entered from?

Each toll plaza has a unique toll plaza number, that is not duplicated throughout the entire system, i.e.:
Boughton Road Plaza 89 on I-355 (main line toll plaza).
Willow Road Plaza 27 (Exit 48 on I-294).

Toll plazas 1 through 19 are on the Jane Addams (Northwest) Tollway (I-90).
Toll plazas 20 through 47 are on the Tri-State Tollway (I-94 and I-294).
Toll plazas 51 through 69 and 81* are on the Reagan (East-West) Tollway (I-88).
Toll plazas 73 through 101* are on the Veterans Memorial (North-South) Tollway (I-355).
Toll plazas 320 through 330 are on the Elgin-O'Hare Tollway (IL-390).

The original toll plazas (except IL-390) were all odd numbers only.  Even numbers and A and B suffixes are toll plazas added later.  the toll plaza numbers have nothing to do with the exit numbers or mileposts.
*Plaza 81 was built with I-355; however, it serves traffic to/from I-88 west from Ogden Avenue.

[J N Winkler]

Empirestate, I believe the Illinois Tollways only have barrier tolls so the duplicate exit numbers may not interfere with tollkeeping records.

ISTHA keeps toll records by plaza number, not milepost or number of any nearby exit.  Checking that an electronic toll has been correctly collected for a toll plaza transit usually entails finding the plaza number on a map.  Plaza numbers are signed (not in FHWA alphabet series) on toll canopies and ORT gantries, and at least some of them are shown on Google Maps (for example, it shows that at the I-80/I-294 merge near Hazel Crest, eastbound is Plaza 45 while westbound is Plaza 43).  But personally I prefer to go to the horse's mouth and download the ISTHA system map in PDF from their website.

(Brandon's post upthread--posted as I was composing this post--goes into more detail on the plaza numbering scheme.)

But if you had duplicate exit numbers on the NY Thruway, how would the controlled toll-ticket system know which of the two exits with the same number you entered from?

One option for the Thruway is simply to repurpose the existing sequential numbers (which BTW are in multiple series) as plaza numbers.  This would entail no recordkeeping changes since exit numbers are already used as plaza numbers on ticketed segments while barrier tolls have their own descriptive codes (GIN = Grand Island North, GIS = Grand Island South), etc.

I know that when I spent a year in Albuquerque, I got to know the area's exit numbers on I-25 and I-40 very well.  Now 14 years later, I don't remember them.

I have never lived in Albuquerque and have passed through very infrequently in the last few years--just once in late September 2014 and again in early January 2017.  Yet I vaguely recall ABQ exits are in the 250's on I-25 and 150's on I-40.  The New Mexico exit numbers I remember best are 275 (Santa Rosa) and 311 (Montoya, because of the nasty S-curve there), both on I-40.

On the other hand, I really struggle to remember any Thruway exit numbers other than 33, and that only because I had to look it up to use it as an example earlier in the discussion.

[cl94]

I have Thruway exits memorized, but that's more because I drive the road so often. I haven't traveled on a distance-numbered road on a regular basis in over a decade.

The Pennsylvania Turnpike codes the plazas as 3 letters. Think a few others might as well. Wouldn't be too hard for New York to do this. Of course, the current plan is AET within 10 years, so it is probably a moot point.

[J N Winkler]

As regards duplication of exit numbers, didn't the Thruway at some point use N18, N20, etc. for the Niagara Thruway, and a different letter prefix for the New England Thruway?  The cross-reference shows duplicate numbers on the mainline, Niagara, and New England segments, with only the Berkshire connector still having a B prefix (presumably because it is part of the same closed-ticket system as the mainline).

[empirestate]

If it is to be done at all, the sooner the better. Permit me to ask outright; do you agree with that final statement?

I mean...not really. It should be done when the value in converting is greater than the value in staying the same, not before.

Ah–so there's the problem. It does indeed matter how unique it is, because we're dealing with the specific situation where you might have an "exit 106" on one part of the Thruway, and another "exit 106" on another part of it. So we see that mile-based numbering isn't completely unique. However, if the first exit were instead called "Circleville Interchange" and the other were called "Squaretown Interchange", then the identification is unique.

False problem.  The Tri-State Tollway has two of the following exit numbers:

"Problem", in this context, refers to a semantical aspect of the discussion itself, not to the duplication of exit numbers.

Empirestate, I believe the Illinois Tollways only have barrier tolls so the duplicate exit numbers may not interfere with tollkeeping records. But if you had duplicate exit numbers on the NY Thruway, how would the controlled toll-ticket system know which of the two exits with the same number you entered from?

Dunno...presumably, any computer that's looking at your "ticket" has got the interchanges ID'd with some kind of code much longer and obtuse than the exit numbers we see on signs (down to the specific toll lane, no doubt). But as for human ticket collectors, they'd probably be looking at–and some of you ain't gonna like this answer–the interchange's name.

[cl94]

As regards duplication of exit numbers, didn't the Thruway at some point use N18, N20, etc. for the Niagara Thruway, and a different letter prefix for the New England Thruway?  The cross-reference shows duplicate numbers on the mainline, Niagara, and New England segments, with only the Berkshire connector still having a B prefix (presumably because it is part of the same closed-ticket system as the mainline).

I think that the N was dropped after the barrier tolls on I-190 were removed. I know it had one at one point; this was done because it connected directly with the mainline Thruway.

No idea if the New England Thruway ever had prefixes, but the old signs with current numbers were button copy. Before 1980, exit numbering reset where NYSTA maintenance began, but I do not know if those had a prefix. None of the current numbers had prefixes. I strongly doubt that prefixes ever existed on the New England Thruway, as it was separate from the rest of the Thruway system until 1990.

[webny99]

If it is to be done at all, the sooner the better. Permit me to ask outright; do you agree with that final statement?

I mean...not really. It should be done when the value in converting is greater than the value in staying the same, not before.

But that fails to consider the accruing benefits of the conversion. You must not believe those values will ever be equivalent, whereas I believe that date is already long-since past, considering the benefits over time. Also, there are no benefits to staying the same, other than to avoid the one-time cost, which is insignificant and petty at best.

And from there it becomes subjective, so that's the end of the road. I'm far more interested in reading any further discussion you have with others than I am in prolonging this. (And if I've been distracting you from continuing your debate with JN, I owe my apologies to both of you).

[webny99]

Thing is, not remembering exit numbers negates most advantages of mile-based system.

Not really; you don't have to remember all the numbers, just the one for your exit. For all other exits, the number is posted on signage for your use as needed - there's no need to know it beforehand, nor is there a need to remember it afterwards.

Anyone having more exposure to mileage-based system than me: can you, from the top of your head, list at least 10-15 numbers along your most traveled route?

Heck, I can almost do three sets of numbers for the thruway - current sequential, current thruway milepost, and "theoretical" I-90 mile starting at Ripley

[jp the roadgeek]

My $.02 on this:  I live in a state where mile markers are very sparse, and BGS mileage signs are virtually nonexistent.  As for NY, if they go mileage based on all highways and parkways, I would use the "OLD EXIT xx"  tabs much like PA, ME, and CT use.  RI's new ones kind of overdo it and the new ones on the portion of 95 becoming 295 in NJ are obnoxious.  As for the Thruway, the easiest solution to learn for most drivers would be internal mileage based, which would start at 1 in Yonkers and go up to 495 near the PA border.  Most drivers think of the Thruwayvas a whole rather than the individual interstates that comprise it.  Granted, I-87 and I-90 would be violating tradition in that exit numbers go DOWN on 90 as you move east to Albany before going up again to the MA border.  Meanwhile, the  I-87 divevfrom the Bronx to Albany would go to MP 8 then suddenly reset to 0 and go up to 148 to current exit 24.  What will really kill the traditionalists is if the Northway is re-mileposted and renumbered based on I-87 mileage from the Bronx.  Exits would start at 157 for I-90 East and go to 332 in Champlain.  What could be done is put 2 sets of mileposts along the Thruway: one set for Thruway mileage, and one set for either I-87 or I-90 mileage.   Also, a drive on I-90 and would be interesting, as exits would decrease from 495 to 148, then jump to 348 for Free 90.  I would renumber the Berkshire Spur exits to I-90 mileage so B1 would be 368, B2 would be 377, and B3 385.  However, the actual exit for B1/368 would not be for Free 90, as the current B1 is part of mainline 90.  it would be for Castleton-on-Hudson traffic much like the 95-93 connection in Canton, MA.

Long story short: keep the exits on the Thruway based on internal mileposts; renumber the Deegan, Northway, Free 90, and Berkshire Spur based on the individual highway, and put two sets of mileposts along the mainline, one for individual highway mileage and the other for internal Thruway mileage.  This makes you wonder if the NJTP will ever renumber to mileposts, and will the exits in the Fort Lee area be updated with I-95 completed?

[empirestate]

I mean...not really. It should be done when the value in converting is greater than the value in staying the same, not before.

But that fails to consider the accruing benefits of the conversion.

How so? I said "the value in converting". That includes the immediate value, the accrued value, whatever. If there's any piece of that I haven't considered, it's because I don't have the information to consider. You guys have mentioned a lot of theoretical benefits–valid ones, to be sure–but I've never seen them quantified.

You must not believe those values will ever be equivalent, whereas I believe that date is already long-since past, considering the benefits over time.

They might be, sure. I've already said that, if the conversion can happen as a side-effect of some other initiative, that alone might be enough of a value offset. Likewise with being bureaucratically forced to convert.

Also, there are no benefits to staying the same, other than to avoid the one-time cost, which is insignificant and petty at best.

That may well be, but I don't need to be persuaded to stay the same, so I don't need to consider the value of doing so.

And from there it becomes subjective, so that's the end of the road. I'm far more interested in reading any further discussion you have with others than I am in prolonging this. (And if I've been distracting you from continuing your debate with JN, I owe my apologies to both of you).

Not in the least. The thread split put a little hiccup in it (it happened during the time I was writing my last lengthy reply to him, so one post is still stranded in the other thread), but hopefully everyone's following along OK. Everyone who cares to, that is...

[kalvado]

But that fails to consider the accruing benefits of the conversion. You must not believe those values will ever be equivalent, whereas I believe that date is already long-since past, considering the benefits over time. Also, there are no benefits to staying the same, other than to avoid the one-time cost, which is insignificant and petty at best.

And since we're talking about benefits.. is there a numeric value attached to those? Reduction of fatal crashes, reduction of accidents, reduced delays?.. Any other factors that materially benefit motorists?

[webny99]

When I visited New York last summer, I used the mainline Thruway several times:  Amsterdam-Albany, Amsterdam-Utica, Rome (really Verona)-Rochester.  I had both Google Maps on my phone and a paper map (the NYS official state tourism map, as it happened).  I was able to estimate my total time/distance commitment for each leg in advance using both resources, but since there were no mileage-based exit numbers I could memorize and I didn't have the Thruway's cross-reference log downloaded to my phone, I could not track progress using the mileposts.

Two lines of further inquiry;

Doesn't the NYS map show the distance between exits? If it doesn't, I'd be rather surprised, and certainly believe that it should include this information.

Also, my typical strategy when using the thruway is to take advance note of the milepost only of my final exit. I can thereby track progress to at least a certain degree. However, I've traveled the Buffalo-Syracuse segment so extensively that I cannot fairly compare my own case to that of someone out-of-state. And of course, I cannot use interim exits to track progress, nor can I find the final milepost (in cases where I don't know it already) with ease, as I could if it was also the exit number.

On the Amsterdam-Utica leg I was thinking "Is Utica just over the next hill?" for about 20 miles.

It's entirely possible, due to the extremely boring and lackluster nature of that particular segment, that you may have had that thought regardless of the numbering scheme

One option for the Thruway is simply to repurpose the existing sequential numbers (which BTW are in multiple series) as plaza numbers.  This would entail no recordkeeping changes since exit numbers are already used as plaza numbers on ticketed segments while barrier tolls have their own descriptive codes (GIN = Grand Island North, GIS = Grand Island South, etc.)

I am definitely a major advocate of this idea
AET would eliminate this scenario anyways, but with the current setup, this is an excellent solution. Exits could be re-numbered based on the respective mileages of I-87 and I-90, and supplementary panels (perhaps yellow?) with the plaza number could be added.

[webny99]

But that fails to consider the accruing benefits of the conversion. You must not believe those values will ever be equivalent, whereas I believe that date is already long-since past, considering the benefits over time. Also, there are no benefits to staying the same, other than to avoid the one-time cost, which is insignificant and petty at best.

And since we're talking about benefits.. is there a numeric value attached to those? Reduction of fatal crashes, reduction of accidents, reduced delays?.. Any other factors that materially benefit motorists?

Given that the benefits are by-and-large intuitive ones, they would prove extremely difficult to quantify. The benefit to roadside businesses is the only one that comes to mind, and it has been discussed upthread to such an extent that I don't see a need to comment further 
With that said, I see the qualitative benefits as much more important than the quantitative ones in this particular case. Exit numbers don't need to reduce crashes or the likes; they need to improve guidance and location identification, and those concepts prove too challenging to quantify in any meaningful or timely fashion.

[kalvado]

But that fails to consider the accruing benefits of the conversion. You must not believe those values will ever be equivalent, whereas I believe that date is already long-since past, considering the benefits over time. Also, there are no benefits to staying the same, other than to avoid the one-time cost, which is insignificant and petty at best.

And since we're talking about benefits.. is there a numeric value attached to those? Reduction of fatal crashes, reduction of accidents, reduced delays?.. Any other factors that materially benefit motorists?

Given that the benefits are by-and-large intuitive ones, they would prove extremely difficult to quantify. The benefit to roadside businesses is the only one that comes to mind, and it has been discussed upthread to such an extent that I don't see a need to comment further 
With that said, I see the qualitative benefits as much more important than the quantitative ones in this particular case. Exit numbers don't need to reduce crashes or the likes; they need to improve guidance and location identification, and those concepts prove too challenging to quantify in any meaningful or timely fashion.

Well, improved location awareness easily translates into accident reduction through reduction of last-second moves towards the exit and reduction of out-of-the way mileage.  Both are already achieved with existing signage.
And  if there is no quantification -  there are no real benefits of conversion. 

[Jim]

I don't know about being able to quantify a benefit, but as one who travels quite a bit outside of the sequential states of the northeast, and at the risk of rehashing the same things everyone else has said upthread, it is nice to be able to do the quick math.  I know I get off at exit 101, and I just passed exit 329 or MM 329 so I know how far I need to go and about how much longer it will be.  If I see a billboard that the next Zaxby's is at exit 220 I can tell how far it will be almost right away (within a minute I'll pass a MM).  If exit 101 was sequential exit 18 or exit 220 was sequential exit 25, I might know it's approximate MM and could do the same thing, but if the exit number can provide that information readily, why not?  On the Thruway, I know I get off right near Mile 173 for Exit 27.  But as a daily commuter on that route, the exit numbers aren't for me, they're for the traveler less familiar with the road.  Take down every sign and I can still get to and from work.

The only argument that holds any weight with me against a switch is that it costs money to do so at a time when there are so many projects that need the funds.  For me, the benefits are worth what I gather is a relatively small expense, and one that can be spread out over a few years and timed to coincide with signing projects happening anyway where possible.

All that said, I do sympathize with the special situation of New York, with the Thruway having its own MM and exit scheme.  I'd still be in favor of dumping the Thruway numbers and number correctly as I-87/I-90, but acknowledge that this adds to both the expense and the length of the temporary learning period as people become familiar with the new scheme.

[webny99]

But that fails to consider the accruing benefits of the conversion.

How so? I said "the value in converting". That includes the immediate value, the accrued value, whatever. If there's any piece of that I haven't considered, it's because I don't have the information to consider. You guys have mentioned a lot of theoretical benefits–valid ones, to be sure–but I've never seen them quantified.

My response to kalvado above is very pertinent here. How do you suggest we quantify any of the benefits?

Also, there are no benefits to staying the same, other than to avoid the one-time cost, which is insignificant and petty at best.

That may well be, but I don't need to be persuaded to stay the same, so I don't need to consider the value of doing so.

Yes, you do; to prove that the value is greater than the value of converting. Surely you must be able to explain the benefits; I (and others) have done so extensively for the other side of the debate. Considering your certainty that we should leave the system unchanged, you must have at least some sort of reasoning that gives credence to doing nothing.

(And if I've been distracting you from continuing your debate with JN, I owe my apologies to both of you).

Not in the least. The thread split put a little hiccup in it (it happened during the time I was writing my last lengthy reply to him, so one post is still stranded in the other thread), but hopefully everyone's following along OK. Everyone who cares to, that is...

That post (which I indeed missed entirely) seems to be here now, so all is well 

[webny99]

Well, improved location awareness easily translates into accident reduction through reduction of last-second moves towards the exit and reduction of out-of-the way mileage. Both are already achieved with existing signage.

How so? Mileage based clearly does more to help motorists identify their location than sequential.

And  if there is no quantification -  there are no real benefits of conversion.

If you're insinuating that qualitative benefits don't exist, well, that's just ridiculous 

[J N Winkler]

Doesn't the NYS map show the distance between exits? If it doesn't, I'd be rather surprised, and certainly believe that it should include this information.

It does not.  In fact, it does not show point-to-point distances for any highway, an omission which I frankly find puzzling.  Utica is listed in the city distance table, but not Amsterdam or Rome.

Even if it did, calculating the distance between exits involves summing up the distances between any interim exits, unless the two exits of interest are considered sufficiently important that a single distance between the two is given (often in a color different from that used for shorter distances).  This is not usually as convenient as simply subtracting one mileage-based exit number from another.

On the Amsterdam-Utica leg I was thinking "Is Utica just over the next hill?" for about 20 miles.

It's entirely possible, due to the extremely boring and lackluster nature of that particular segment, that you may have had that thought regardless of the numbering scheme

It was pitch-black dark at the time, so I was actually happy for it to be fairly unchallenging in terms of curves.  New York is fortunate to have the easiest crossing of the Appalachians north of Alabama/Georgia and the Thruway was considered a model of good alignment design back in the 1960's because it was one of the few freeways that used long curves with extremely large curve radii (up to about 85,000 ft, if memory serves) rather than long tangents connected by shorter curves of lower radii.  And I could have made it easier for myself by taking a note of the milepost corresponding to each mileage sign and using that as the basis for distance-left estimation.  But when exit numbers actually correspond to the mileposts, the process becomes more intuitive.

And since we're talking about benefits.. is there a numeric value attached to those? Reduction of fatal crashes, reduction of accidents, reduced delays?.. Any other factors that materially benefit motorists?

There are some big-data approaches that can be tried.  For example, each Thruway milepost has a corresponding latitude/longitude and there is a small latitude-longitude area where the milepost fits in StreetView "spill" (i.e., is visible in StreetView).  If Google Maps data suggests there is a significantly higher frequency of StreetView viewing of mileposts near exits along a freeway with sequentially numbered exits, then this is a sign customers are looking for information the signing does not already provide them.

An agency such as the Thruway also has access to customer feedback regarding the burden of having to cross-reference sequential exit numbers with mileposts, as well as hit counts for the existing exit number/milepost cross-reference.  It can also conduct surveys to measure the strength of customer preference for mileage-based exit numbering (disaggregating responses according to whether respondents live in or come from states that already have mileage-based numbering), and poll agencies in other states on their experiences converting to mileage-based numbering.

So, no, it is not impossible to develop quantitative evidence for benefits.  It becomes a little more difficult, but still not impossible, when it is desired to differentiate between stated and revealed benefits.  And the lack of existing evidence does not prove that there is no evidence to be found if it is searched for.  The large number of agencies that have started out with sequential numbering and changed to mileage-based in the absence of a federal mandate is in itself a significant willingness-to-pay argument.

As for the Thruway itself, I expect it to convert eventually, not on the strength of research into the benefits (I don't know if it is a research-driven organization), but simply because it will eventually run out of directors willing to back the rank-and-file's preference for the status quo.  This is essentially what happened to Caltrans.  The rank and file was bitterly opposed to exit numbering, except for engineers who had trained out of state.  Then Jeff Morales (former Illinois DOT head) became Caltrans director and that was it.

Since Cuomo has been governor, the Thruway has had an awful lot of directors--how many is it now?  Seven?  Eight?  That alone raises the odds someone will be brought in from a state with mileage-based numbering, just to avoid promoting a coffee-getter straight into the wood-paneled office.

In a previous post on exit numbering in NYS (I don't know if it has been ported to this thread), Rothman blasted a nameless Thruway official who proposed an over-elaborate conversion strategy calling for "New Exit" signing for a couple of years, followed by the actual changeover of exit numbers and then "Old Exit" signing for a further couple of years.  This idea may be moronic in terms of cost and compliance with MUTCD requirements, but it strikes me more as a move--straight out of Francis Cornford's Microcosmographia Academia--to kneecap exit number conversion by making it seem absurdly expensive.  One problem with such stratagems is that once you run out of true believers, they start to look like protesting too much.

Upthread, I suggested exit numbering conversion might happen under FHWA pressure, but this is not to discount the possibility of its occurring without HOTO sending any nastygrams to Albany.

[Duke87]

But again, remember that we're addressing the specific problem of overlapping systems (I-90, I-87, Thruway, Northway, etc.).

The simplest solution to this problem would be to dispense with the overlapping systems. Cease and desist signing the New York State Thruway as a thing and just sign it as I-87 and I-90. Number all of the exits accordingly, and at the current location of exit 24 delineate what is the through route versus an exit accordingly.

This is how Connecticut solved this problem. It's a good solution.

[cl94]

But again, remember that we're addressing the specific problem of overlapping systems (I-90, I-87, Thruway, Northway, etc.).

The simplest solution to this problem would be to dispense with the overlapping systems. Cease and desist signing the New York State Thruway as a thing and just sign it as I-87 and I-90. Number all of the exits accordingly, and at the current location of exit 24 delineate what is the through route versus an exit accordingly.

This is how Connecticut solved this problem. It's a good solution.

This. Not that hard of a concept.

[kalvado]

Well, improved location awareness easily translates into accident reduction through reduction of last-second moves towards the exit and reduction of out-of-the way mileage. Both are already achieved with existing signage.

How so? Mileage based clearly does more to help motorists identify their location than sequential.

And  if there is no quantification -  there are no real benefits of conversion.

If you're insinuating that qualitative benefits don't exist, well, that's just ridiculous 

Motorists passing exit X and targeting for exit X+1 are warned that exit is close enough to start planning for exit. E.g. changing lanes and slowing to speed limit +5. Of course this is not without glitches - but missing exit is unlikely, and signage is usually there. Mileage based has minor, if any advantage in that regards.
Qualitative benefits may exist, but until they cannot be expressed in terms of solid numbers, commiting to a multi-million process of renumbering is not warranted. Those money can be spent on other project leading to clear and quantifiable safety improvements - like bridge maintenance.

To make things worse, GPS navigator may be less than ideal tool - but directing to highway exit is almost 100% reliable. And as acceptance of technology goes up, even those qualitative benefits are reduced.