Who writes the clever road warnings that appear over Utah's highways?

SALT LAKE CITY — On the Fourth of July, drivers on Utah's freeways were treated to the reminder, "You're not a firework; don't drive lit." On Pioneer Day, they were told, "If yer eyes are saggin', pull over yer wagon."The warnings on the overhead variable message signs (VMS) are designed to be eye-catching as drivers cruise down Utah freeways. "Message Mondays" usually feature clever word play or something themed to a holiday, while Friday posts feature statistics, usually pretty grim: For