While planning a route for a placarded, non-radioactive hazmat load, you learn that the state you are driving through has designated certain tunnels and downtown streets as off-limits to hazmat traffic. Are these state-level restrictions valid?

49 CFR 397.71; AAMVA CDL Manual Sec 9.6.5 (nhcdm.pdf p.9-14)

Route and permit rules change often and vary by state and locality, and the responsibility for knowing them falls on the driver, not just the carrier's dispatcher. Driving a placarded load through a restricted tunnel or downtown corridor on the assumption that a placard permits travel anywhere can trigger citations and, in a populated area, dramatically worsens the consequences of any incident.