68:4 Tefillas HaDerech should be recited while standing. If the traveler is riding on an animal or in a wagon, if it is possible to pause so that one may recite it, he should do so. (He need not get down from the animal or get out of the wagon; stopping in place is sufficient – Mishnah Brurah 110:23.) This is because saying Tefillas HaDerech while riding is like reciting it while walking. If it is not practical to pause, then one may say it while riding.
68:5 One only says Tefillas HaDerech once a day for the duration of the journey. However, if one stopped in a city with the intention that he would spend the night there and later changed his mind and left, either to continue on his way or to return home, he should then recite it anew. If a person travels both by day and by night, or if he spent the night in an uninhabited location, he should recite Tefillas HaDerech with its concluding phrase (“Baruch Atah Hashem…”) the first time and without the concluding phrase for the balance of the journey. This is because the whole time that he does not stay in a settled area is considered to be a single leg of the journey.