Illustration of traffic barricades, from the Manual on Uniform Traffic Control Devices for Streets and Highways (2009 Edition)
<a href="https://en.wikipedia.org/wiki/Federal_Highway_Administration" class="extiw" title="w:Federal Highway Administration">Federal Highway Administration</a>, <a href="https://en.wikipedia.org/wiki/United_States_Department_of_Transportation" class="extiw" title="w:United States Department of Transportation">United States Department of Transportation</a>
2009-12-01
Manual on Uniform Traffic Control Devices for Streets and Highways (2009 Edition)