Both of the words in this sign contain affixes. Affixes are specific consonants, consonant clusters and sometimes consonant/vowel combinations which are inserted at the beginning of a root word (prefixes) or into a root word (infixes) to create a new word. Some examples:
Given the above knowledge and the additional information that this sign is an "official" roadsign directed at motorists, see if you can make any guesses as to the meaning of the second word in the sign relative to a root word you already know.