I'm a bit of a snake buff, so I might be of help if you haven't already gotten a solution in the almost-month this comment's been up. Snakes, though simple, are easily stressed, much like fish. If you're on a road trip, try to keep your friend as still and as close to you as possible. Plastic mini-terrarium boxes work great for baby ballies, but if you've got a two-footer or longer, you may have no choice but to get a storage bin and punch airholes in it, securing the top with tape. I say plastic because of its shock absorbency, as opposed to glass, which not only breaks easily, but could hurt your snake in the instance it does. For plane trips, you may have to have him/her put in the luggage compartment. I wouldn't like to do it, but it may be the only option, especially if you're seated with an ophidiophobe.
If you have to put the snake in the luggage compartment, I've read that the best way to go about that is to put them in a snake bag in teh container, and make sure that they cant slide around or get thrown against the side in case of sudden movements. Too much insulation though and the snake could overheat if you are traveling to a warmer place than where you started. Always make sure that the snake has access to fresh air though I haven't had to ship or take a snake on an airplane/boat as of yet, but I do take my 4 year old ball python with me in the car he likes to snuggle around my neck and look out the window, much to the dismay of other drivers xD I find he's much happier when he's not stuck in a snake bag during a trip.
I don't do much driving yet (and if I drive he's not even in the car) but my parents are both very safe drivers The farthest I've traveled with him was probably only ten miles, it's usually just to the pet shop a couple blocks away because The owners breed ball pythons and they have me bring mine in if they're acting weird or wont eat or something If I was going any farther than that I wouldn't have him out at all.
I love snakes 8D I used to have a baby garter snake as a pet and he/she (lol idk what it was) was soooo cute X3 I love big snakes too C: I hate when people are so afraid of them, or they think they're gross. They're not gross at all