Hello GypsyRosalie: I have read several posts recently, here on PC, written by members who experience significant levels of fear driving & / or riding. The thing you probably need to check into is a program or company that provides systematic desensitization (graduated exposure therapy.) This is a type of therapy where a person is gradually exposed to whatever it is they fear. It is done slowly & carefully so as not to create additional stress. Beyond that, individual therapy & / or medications may be helpful By the way, driving behind, or beside, a semi is a bad idea. So, in this case, your fears are not unfounded.