This image is from a collection commissioned by the <a rel="nofollow" class="external text" href="http://dot.gov/">United States Department of Transportation</a> and designed by <a rel="nofollow" class="external text" href="http://www.aiga.org/">AIGA</a>.
Converted to SVG by <a href="//commons.wikimedia.org/wiki/User:Evil_Monkey" title="User:Evil Monkey">User:Evil Monkey</a>.
<a rel="nofollow" class="external free" href="http://www.aiga.org/content.cfm/symbolsigns">http://www.aiga.org/content.cfm/symbolsigns</a>