A road sign located on the Pennsylvania Turnpike at the Allegheny Mountain Tunnel, that prohibits vehicles carrying certain Hazardous Materials from the tunnel and directs them to exit the toll road at the exit.
Vectorization of Prohibitionboard.jpg by Shanel.

The Placards, were pulled from the 2016 Emergency Response Guidebook, a work of the United States Department of Transportation.
The Navigators