Radio or other means of communication not hereinabove referred to in Section 7677 may be used for the purpose of transmitting orders for the movement of trains, subject to such rules or regulations as the commission may promulgate for insuring the safety of railroad operations.
Source:
Section 7677.1, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=PUC§ionNum=7677.1..