The Federal Highway Administration issued an interim approval for bike signals, based on the NITC project "Operational Guidance for Bicycle-Specific Traffic Signals." The project, selected in 2015 as one of AASHTO's "Sweet Sixteen" high-value research projects, has been widely cited and the research is instrumental in beginning to standardize the use and design of bicycle signals.
This video provides a look at what that means for jurisdictions in the United States: