follow the clues

whenever I see these spray-painted street markings, it reminds me that someday I want to write a story in which very important and very secret messages are hidden in plain sight alongside these boring-but-mysterious codes for construction workers.

don't they look like they could secretly be pointing the way to some amazing treasure or a secure rebel hideout or rendezvous point?

the trick of successfully hiding your heroes' secret messages among such mundane non-secret signs would hang on how well the secret codes can balance blending in with the real marks and standing out from them at the same time. you wouldn't want to mislead the construction crews with marks that looked legitimate but didn't provide any meaningful information. you also wouldn't want too many random suburbanites getting in search of a garage sale that didn't exist (although depending on the stakes for our rebel alliance's secret missions, this actually might be an acceptable cost).

I've also daydreamed about the heroes of this story sending coded messages via weekend garage-sale signage or random highway-side propaganda posters. or maybe in the windows of an old car in someone's side yard-- "For Sale, 255K miles, $600, 555-251-9839" could be the master key to deciphering the next series of secret codes. if the car is facing west, decode everything backwards instead. and if any innocent party calls the phone number, nobody will answer.

it's fun to think about this kind of covert-messaging-in-plain-sight. in a sense, all the spray-painted lines and shorthand markings on the street are already a secret code. not a very important secret, but more or less black-boxed from most regular everyday people. these marks have a relatively narrow audience, and the rest of us either ignore them or create elaborate daydreams in which an even narrower audience can read beyond their surface meanings and thereby figure out where to safely deliver some top secret packet of highly incriminating evidence.

to make sure our secret agents can reliably distinguish and decipher the messages intended for them, would they have to become fluent in all the regular street marking conventions of their region? in that case, this piece from the BBC could be useful.

there is also a 99% Invisible article all about utility markings and their history in various countries. pretty interesting stuff.

seeing enigmatic secrets like this in mundane, utilitarian stuff is a little Dan Brown-esque I suppose. I promise, if and when I write such an adventure story, I'll try my best not to make it so blatantly sensational and pulpy.