California Code, Streets and Highways Code - SHC § 26083

The member appointed by theCalifornia Transportation Commission shall hold office for the term of four years from and after his appointment, and until the appointment and qualification of his successor.  All appointments to fill any vacancy in the position of that member either during or at the expiration of his term of office shall be made by theCalifornia Transportation Commission upon the receipt of written notice from the commission of the vacancy.  No petition shall be necessary to authorize the appointment to fill the vacancy.