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Subsidiary placard placement


172.505 and 172.516

Regulation summary

Section 172.505 establishes the general placarding requirements for subsidiary hazards, and 172.516 establishes the visibility and display of placards.


In this scenario, a carrier asks where on a transport vehicle a subsidiary hazard placard must be placed in relation to the primary hazard class placard with which it is associated.

In this interpretation, PHMSA addresses the proximity of subsidiary placards in relation to primary placards.

Interpretation Summary

In interpretation Ref. No. 07-0071, PHMSA advises that the subsidiary placard must be placed in relation to the primary hazard class placard.

  • The HMR specifies that the subsidiary placard must be placed above, below, or to the left or right of the primary hazard class placard.
  • Subsidiary hazard placards, when required under 172.505, must be placed on each side and each end of the transport vehicle, freight container, portable tank, unit load device, or rail car.
  • The requirements for visibility and display of placards in 172.516 apply to placards representing both primary and subsidiary placards.