We currently install base posts, lap splice joints and a sign post for all signage. According to page 14 paragraph 3 of the 2010 FHWA Guide Maintenance of Signs and Sign Supports: "A U-channel post of re-rolled rail steel weighing 3 pounds-per-foot or less meets breakaway requirements by itself."
Is that still an acceptable standard for breakaways?
Below, under resources, are links to the current and older eligibility pages that describe the breakaway standards. In the near future, all breakaway hardware is being retested to a newer standard called the Manual for Assessing Safety Hardware (MASH), but for now the old standard is still useable.
A 3 pound post is still acceptable, but, if you are looking for an added level of assurance, you can ask your supplier to provide the certification letter with the delivery of the materials. A certification letter puts the onus on the supplier to provide material that meets current requirements.
Sign Support, Mailboxes & Delineators Eligibility – Current Criteria
Sign Support, Mailboxes & Delineators Archive – Former Criteria
AASHTO Guidance FHWA Webpage – Manual for Assessing Safety Hardware