Quoted from Coyote:

As someone that works with traffic control devices (signs, signals, etc), this is the closes one I like.
However, the font choice really bugs me, since it's not a DOT-approved font. Look up the TTF/OTF font BlueHighway. While it's not the OFFICIAL font, it's so close that you can't tell. Try using any one from that group.
And yes, I could have an actual road-sign made up like this, easily.

Quoted from Coyote:

Publics Project manager for a railroad - deal with city, county, state gov'ts all the time, dealing with signs and pavement markings and all kinds of crap. Working with the contractors on-site, those guys love handing me old signs that are taken down. ... Not sure why, but now I have enough signs to populate I-70 from Baltimore to Denver.