Thread by @mattbramanti

due to logistical issues, I have to postpone the razor-blade thread to next week

in the meantime, let's talk about these little guys

🧵

this is an Interstate Highway sign

it's part of a system of standardized signage used on Interstate Highways in the United States

you might just call them "freeways" but the network of roads is officially the Dwight D. Eisenhower National System of Interstate and Defense Highways, named for the president who signed the Federal-Aid Highway Act of 1956

the system has nearly 50,000 miles of highways criss-crossing the Fruited Plain

Interstates are all controlled-access roads, meaning they use on- and off-ramps and do not cross other roads at grade

the biggest one in the world is about 300 yards from my front door

Interstates are designed and built to standards promulgated by the Federal Highway Administration, an agency of the U.S. Department of Transportation

that department is led by Secretary Pete Buttigieg, shown here absolutely devouring that hog

with a standardized network of roads, you need a standardized system of signage

that's set forth in the Federal Highway Administration's Manual on Uniform Traffic Control Devices for Streets and Highways, or MUTCD

mutcd.fhwa.dot.gov/kno_11th_Editi…

this manual, along with the Standard Highway Signs publication, goes into excruciating detail on sizes, dimensions, colors, typefaces, you name it

for example:

speed limit signs in kilometers per hour, like you might see near the Canuckistani border, must have the limit circled

so let's talk about each kind of sign

the Interstate shield is used to mark Interstates

states may optionally include the name of the state

the number represents the number of the highway

east-west Interstates have even numbers, with the lowest numbers in the south of the country and rising as you go north

when complete, I-2 will run from Peñitas, Texas to Harlingen, Texas

I-96 runs from Norton Shores, Mich. to Detroit

north-south Interstates have odd numbers, with the lowest numbers in the west and rising as you go east

I-5 runs from the Mexican border at San Ysidro, Calif. to the Canuckistani border at Blaine, Wash.

I-99 runs from Bedford, Pa. to Painted Post, N.Y.

three-digit numbers represent either a spur or a loop around a city

spurs have odd first digits, loops have even first digits

the next two represent the parent highway

for example, this one is a loop around Houston, bisected by I-10

avoid at all costs

Alaska's Interstates are kinda weird

they're just numbered A-1 through A-4

and nobody calls them by their numbers

and they're not interstate

and they're not controlled-access

just two-lane roads

that view though

Hawaii's are - you guessed it

H-1 through H-3, plus H-201, which loops around Honolulu

the MUTCD specifies different colors for different classes of signs

red means a full stop is required

orange is for temporary warning signs related to construction

yellow is for warnings about the condition or design of the upcoming segment of highway

green is for guide signs, exits and mile markers

in Colorado and Idaho, they replaced the mile marker 420 signs with 419.9 because stoners kept stealing them

i'm sure they steal those too

black and white are used for regulatory signs

most of these are speed limits, but there are others

blue is used to inform drivers of upcoming services or the lack thereof

spots on these are for sale

the rules and prices are set by each state

jalopnik.com/heres-how-much…

brown is for cultural, historic and recreation sites

apparently pink is used for temporary incidents

I have never seen one of these

the typefaces are specified by Federal fiat, in Standard Alphabets for Traffic Control Devices

right down to the kerning and leading

mutcd.fhwa.dot.gov/SHSe/Alphabets…

so what are the signs made of?

they can be plastic or wood, but they're almost always aluminum

they're faced with a material called "sheeting," which has little prisms or spherical glass beads in it

this allows them to be retroreflective

they reflect light back in the direction it came from

which is the front of your car

which is pretty close to your eyes

hey they're just like retroreflective pavement markers

what luck!

the Federal Highway Administration has detailed specifications for the required coefficient of retroreflectivity of various materials in various colors

highways.dot.gov/safety/local-r…

the poles can be wood or steel (tube, U-channel or I-beam)

regardless of the material, they have to behave well when struck by a vehicle

they can be:

-breakaway (the pole breaks off and flies over the car when you hit it)

-yielding (it bends flat and you run over it)

-shielded (blocked by a guardrail or other barrier)

here's a breakaway pole

those bolts are narrowed at the flange to weaken them

just like fire hydrants!

the Federal Highway Administration even recommends anti-theft measures

to include hammering the end of the bolt holding the sign to the pole

this offends me

highways.dot.gov/safety/local-r…

but I have to say my favorite part of the Manual on Uniform Traffic Devices is this

the errata

dozens and dozens of acknowledged errors



please fix, Mayor Petemutcd.fhwa.dot.gov/htm/11th/error…

so that's the signage

now a little history on the Interstate Highway System

in 1919, the U.S. Army Motor Transport Corps sent a convoy from Washington, D.C. to Oakland, Calif. to test the Army's cross-country mobility

the convoy of 81 vehicles took 62 days to drive the 3,251 miles

that's 52 miles a day

a day

virtually nothing between Nevada and California was paved

the convoy included cars, motorcycles, heavy and light trucks, 39 officers and 258 enlisted men

among the officers was this fella

28-year old brevet Lt. Col. Dwight D. Eisenhower

Ike would later contrast those dusty roads with the Reichsautobahnen

the Federal-Aid Highway Act of 1956 would allow states and localities to site Interstates, with Uncle Sam kicking in up to 90 percent of the funding

there's an urban legend that the Act required one in five miles of Interstate to be straight and level, so that it could be used as a military airstrip in case of war

this is not true

there were pilot programs in the 40s to identify lengths of highway that could be so used

the Australian government has identified segments of outback roads for emergency use by the Royal Flying Doctor Service

during the Cold War, Sweden had a dispersal plan to spread its air force across the country in case of war

this included building mini-airbases all over the country, many of which used highways as runways

anyway, i'm rambling at this point

that's Interstate signage

i hope you enjoyed it; if I missed anything or got anything wrong, let me know

previous deep-dive threads are here:

next one will be on razor blades, next Friday

dammit

that should read "virtually nothing between Illinois and California was paved"

I regret the error