fern k hahn

i think this is different, though, as there's no experience of physical discontinuity for the highway user?

hmm, what do you mean by this? none of these are a break in free-flowing continuity

i forgot to be upset about 99 because honestly it doesn't hold a candle to north carolina's number crimes. but sure, it's a few numbers out of grid

I-676, you weird little thing

(this isn't the only place on the network this happens, but i think it's probably the most unforced instance)

i hadn't known about the symbolism. neat!

the western I-76 was originally I-80S, similar to the western I-84. per wikipedia, so were parts of the eastern I-76, though that seems to have a messier history.

everyone talks about the number… whatever. it's also signed north-south to match its source state route despite running cleanly east-west, but again, whatever — I-980 does the same. what gets me is that it's topologically backwards, as northbound I-238 branches cleanly to the left of westbound I-580

i know nothing about the place but i like looking at these towns and their weird little beltways

Google Maps satellite screenshot of Tyler, Texas and its environs. US 69 travels north-south through the city, I-20 travels east-west to its north, and Loop 49 makes an incomplete loop to its west and south.

they don't seem to make new US routes anymore, so i think we'll have to get texas loop 49 upgraded to I-420

damn! didn't expect to see that again. it's been a while

oh, sorry, i still have my roadgeek hat on. i'm cool with I-14 because it doesn't break any rules, but of course i don't approve of any of this

can't wait for its concurrency with US 69 in lufkin to come online

oh, whoa, is that kurumi signmaker?

what do you think of I-69C

three-digit interstates are secondary routes whose numbers are only unique within each state. there are eight different interstates 295, all related to I-95!

just happy to have an audience!

north carolina is on a spree of claiming numbers with no buy-in from its neighbours. the new bits of 74 and 87 are entirely within NC. old I-74 ends in cincinnati; new 74 picks up in mt airy, running SE until it *merges* with existing US 74. old I-87 ends in NYC… i don't even know.

by the way, some of those incomplete routes i mentioned earlier are fairly messy situations. I-69 originally ran from indianapolis to port huron, MI; now it extends in bits and pieces all the way to south texas, crossing US 69 and splitting into three lettered branches: E, W, and… C, for central.

if you're wondering: I-80 could probably stand to be numbered 70, but the I-70 we got couldn't have used 60 or 50 because of its proximity to the US routes that bear those numbers.

in particular, the western I-84 (portland to east-of-salt lake city) used to be called I-80N, but it was renumbered as letter suffixes were phased out of the system. I-82 had been taken by a route primarily within washington state, which now lies anomalously to the north of I-84.

the duplicate interstates are all high evens, meaning they're east-west routes across the northern US. i think it just happened that there are more than four primary routes between I-80 and I-90, the central and northern of the three cross-country interstates.

this all means that a given primary interstate has a fairly limited pool of numbers to choose from. the number must be similar to (ideally between) those of parallel interstates, its parity must correspond to the route's orientation, and it shouldn't match that of a nearby US route.

the interstates were preceded by the US routes (the ones with white shields), whose route numbers follow similar rules but increase in the opposite directions. interstates were numbered how they were in order to avoid similar numbers meeting across the two systems. (I-95 ≈ US 1; I-5 ≈ US 99)

primary (1–2-digit) interstates are numbered roughly according to a grid: odds run north-south, numbers increasing eastward; evens run east-west; numbers increasing northward; major routes are multiples of 5. (think I-95.)

bear with me as this will be a multi-parter and i'm sure my knowledge is not complete

started a response here, and i could continue…

yes! this fact is actually how i first heard of "Ok Computer", if that tells you anything about me.

there are several duplicate 2-digit interstate numbers in the high evens: 76, 84, 86, 88. there are also isolated bits of theoretically continuous routes under construction: 49, 57, 69, 74, 87

i don't watch all his videos but i couldn't miss the one about australia's route numbers. gosh, how do you all live with yourselves

the highly consistent and visible rules and typologies and signage are just irresistible. less defensibly, i found myself mourning the alaskan way viaduct when i visited seattle in 2019

you guys like highways, right?