News:

The AARoads Wiki is live! Come check it out!

Main Menu

Arizona Mileposts

Started by Rover_0, March 02, 2014, 08:12:26 PM

Previous topic - Next topic

Rover_0

I'm aware of how Arizona numbers its mileposts,* but I feel that this topic deserves a thread of its own. How long has Arizona been doing this?

Also, I'm not sure what route you would need to take to trace back US-89A's (MP 613 at Utah line) mileposts?

*Branching highways' mileposts continue as you go N or E from a junction.
Fixing erroneous shields, one at a time...


hotdogPi

#1
I'm not sure how they're different from the other states, so this will require some explanation for the people that don't know.
Clinched, minus I-93 (I'm missing a few miles and my file is incorrect)

Traveled, plus US 13, 44, and 50, and several state routes

I will be in Burlington VT for the eclipse.

NE2

pre-1945 Florida route log

I accept and respect your identity as long as it's not dumb shit like "identifying as a vaccinated attack helicopter".

corco

#3
The 613 is pretty straightforward. Follow US 89A to old US 89 (roughly US 89 to I-40 to SR 89 to US 93 to US 60 to SR 79 to SR 77 to old I-19 Business to the I-19 frontage road to I-19 Business to the border)

swbrotha100

#4
Quote from: 1 on March 02, 2014, 08:14:29 PM
I'm not sure how they're different from the other states, so this will require some explanation for the people that don't know.

Some routes don't start at zero with the mileposts. They carry over from junctions with other routes.

Konza

I know this thread is over five years old, and it may be bad form to bump it, but I'm fairly new to Arizona and wonder if, in the five years since the topic was first raised, somebody may have joined the board who can provide some insight on this.

Does anybody know why the mileposts on Arizona's state and US highways are numbered the way they are?

It's perplexing to see low numbered mileposts on highways like SR 82 and 83, and US 191, but numbers over 300 on relatively short routes like SR 90 and 92.

If someone has some history and/or background on this, it would sure be appreciated.
Main Line Interstates clinched:  2, 4, 5, 8, 10, 11, 12, 14, 16, 17, 19, 20, 24, 25, 26, 27, 29, 30, 37, 39, 43, 44, 45, 55, 57, 59, 65, 68, 71, 72, 74 (IA-IL-IN-OH), 76 (OH-PA-NJ), 78, 80, 82, 86 (ID), 88 (IL)

Roadwarriors79

This link show's Arizona's current state highway system. Don't know when it was last updated.

https://www.azdot.gov/docs/mvd-services/state-milepost-system-maps.pdf

In the past, some routes would just continue the mileage from another route. Also, some US routes were decomissioned, but their mileposts were retained even if the number changed.

Some examples:
-- I-17 from Cordes Junction to Phoenix inherited its mileposts (and exit numbers) from AZ 69. AZ 69, when it went to Phoenix, branched off of old US 89 near its milepost 201.
-- AZ 85 north of I-8 replaced part of old US 80, but the mileposts from US 80 were retained.
-- AZ 89 used to be US 89. Even though the number changed, the old mileposts for US 89 were retained.
-- US 60 used to go into California. It was replaced by I-10. The western beginning of US 60 continues the mileposts of I-10 near Brenda.



The High Plains Traveler

#7
Some oddities on the map, assuming that Arizona uses the usual convention of mileposts increasing west to east and south to north. U.S. 93 starts at 0 at the Nevada line and increases southward toward Kingman, rather than having a mile 0 at the south end of old AZ-93 in Nogales. It implies that the mileposts were originally set during the brief period in the 1930s when the road was only U.S. 466. Also, AZ-85 north of Gila Bend not surprisingly picks up from I-10 - or, more accurately, continues the original U.S. 80 mileposts. But south of I-10, it starts at mile 0 and increases to the south to the Mexican border. The mileage also is picked up by AZ-86 going east, and so the 85-86 combination does have a logical mile 0, if that was the intention. 
"Tongue-tied and twisted; just an earth-bound misfit, I."

Konza

No shortage of oddities, even if one understands some of the history involved.

Main Line Interstates clinched:  2, 4, 5, 8, 10, 11, 12, 14, 16, 17, 19, 20, 24, 25, 26, 27, 29, 30, 37, 39, 43, 44, 45, 55, 57, 59, 65, 68, 71, 72, 74 (IA-IL-IN-OH), 76 (OH-PA-NJ), 78, 80, 82, 86 (ID), 88 (IL)

Roadwarriors79

For Loop 303, ADOT basically added 100 to the mileposts to cover a southern extension of the route.

JKRhodes

Quote from: Konza on July 24, 2019, 05:50:20 PM
No shortage of oddities, even if one understands some of the history involved.

Agreed. Following reroute of US 70 on new alignment north of the San Carlos Lake, the mileposts were renumbered along the new alignment, and then all the way up the old alignment to a random location between Fort Thomas and Pima. The result is a jump in milemarker numbers from 314 to 326 within the span of a mile.

On US 191 north of Morenci, the highway is rerouted frequently to accommodate operations of the large copper mine. As a result, that road has become longer, and Mileposts 173-178 repeat themselves.

Roadwarriors79

I would hope that someday ADOT fixes mileposts (and exit numbers) on their interstates someday. I-17 seems unlikely. I-19 may one day not have all metric signage. If/when I-11 gets built in Arizona, hopefully the mileposts are normal and not just inherited from US 93.

707

Yeah, I've noticed the pattern with most Arizona mileposts is that they all stem off a bigger highway connection at the beginning terminus or reflect retired mileage that no longer exists. The US 60 and SR 89A examples listed above being big ones. SR 85 is another similarity. The mileposts change to 3 digits after you leave Gila Bend because they reflect old US 80 and stem off the mileage of I-8 and I-8 Business, which also take milepost numbers from US 80 or are exactly the same as US 80 due to sharing common mileage totals between Yuma and Gila Bend.

As for SR 80, the mileposts don't make sense. When I did personal measurements of both pre-1956 and post-1956 US 80, the numbers were way off. SR 80's mileage doesn't even seem to reflect I-10 or I-10 Business. In 1956, the ending milepost (if it existed at all) on US 80 would have been roughly around 486 at the New Mexico border. Before 1956, it was approximately 496 to 498. The current milepost is 401. To prove the point that it's not connected with I-10 (at least the current mileposts along it or its business routes), the beginning milepost of SR 80 in Benson is 293. The milepost at I-10 Business at the same exact location is 305.63. When this intersection used to be the junction of US 80 and SR 86, the US 80 milepost in 1951 would have been 375.79.

I'm guessing this is because SR 80's mileposts are based on older I-10 ones? SR 90's beginning milepost near I-10 is 289 where the milepost on I-10 is 302.67.



Opinions expressed here on belong solely to the poster and do not represent or reflect the opinions or beliefs of AARoads, its creators and/or associates.