Well the most common method to practice when you are traveling, is probably mental practicing.
Back in Germany I would take the train a lot, or travel on the bus/plane to different countries for concerts and always have the score with me. I managed to figure out bowings and fingerings and interpretations. Playing the music through in my head and moving the fingers without my violin has been actually proven to be as helpful as practicing with the instrument. Here is a link to a great article about mental practicing:
Also I learned the hard way, that practicing simply scales for even just 10 min a day, every day improves your technique incredibly. My former teacher also showed me a great exercise to practice, which improved intonation by probably 100 %. It goes 1st position, 1st 2nd 3rd 4th fingers starting out in half step positions, repeat twice. And then you move the 4th finger half step up, so it’s going to be full step, and 3rd 2nd and 1st fingers follow with half steps, so that by the end you reach full step distances between all fingers in the 1st position. Then you go up with the entire hand by half a step up, to 2nd position. And repeat all of that.
Of course when I was younger, the books to live by were Schradieck and Sevcik. Here is a link were you can find some scores for them: http://www.violinonline.com/techniqueexercises.htm