The requirement for crashworthiness of objects within the clear zone is not tied to traffic sign retroreflectivity, but retrofits of sign supports should be done in conjunction with retroreflectivity. This requirement has been in place for over 10 years in the Manual on Uniform Traffic Control Devices 2000 edition. The 2003 edition of the MUTCD established a 10 year implementation period to retrofit sign supports on highways signed at 50 mph or greater.
The requirement for crashworthiness is found in the MN MUTCD, section A.19, page 2A-18 (PDF, 365 KB)
Post-mounted sign and object marker supports shall be crashworthy (breakaway, yielding, or shielded with a longitudinal barrier or crash cushion) if within the clear zone. Compliance Date: January 17, 2013
This requirement does not specify the type or weight of post; it only requires it to be crashworthy. Meaning, the post has been tested and passed one of the following testing criteria:
- National Cooperative Highway Research Program Report 230
- NCHRP Report 350
- AASHTO Manual for Assessing Safety Hardware
The FHWA has developed a video to provide additional information about these testing criteria.