As you’re aware, the RRFB under Interim Approval 11 was rescinded in December due to patents issued and pending. The FHWA has been informed and has confirmed that the patents have been expressly abandoned, and the RRFB is once again eligible for provisional use through another Interim Approval. Please note that this is a NEW Interim Approval (IA-21), which has been updated to reflect more recent research and experience with the device.
UPDATE: Colorado's Use of Rectangular Rapid-Flashing Beacons
CDOT Traffic and Safety division has submitted a statewide blanket request for Colorado to implement the IA-21 RRFB. They are doing this statewide, for all roads open to public travel, so each individual agency does NOT have to request approval themselves. This does NOT mean you have to implement it or allow it on roads in your jurisdiction, but IF/when you chose to, you would not have to request permission from FHWA - there would already be this blanket approval in place.
Please let all local agencies in your region know that CDOT is submitting this request to FHWA. We will let everyone know when/if CDOT receives the approval from FHWA. The conditions and further detail are attached and accessible at the link below.