MUTCD compliant to can be combined with many options TraffiCalm’s SA328
On 12/2017 FHWA terminated the Rectangular Rapid Flashing Beacon (RRFB) IA-11 due to patent dispute. On 3/20/2018 FHWA came out with a new Interim Approval IA-21 to reinstate the use of RRFBs. There are differences to the two interim approvals so please refer to MUTCD regulations.