Travel Distance that Requires Tefilas Haderech
10. Parsah. The brachah is only said when traveling a parsah (שו"ע שם ס"ז)–3.84km [הגר"ח נאה] or 4.6km [חזו"א] as there is little danger of wild animals and bandits within a parsah of a city (מ"ב סק").
11. Shiur of distance. The brachah is said whether one travels by foot, car, train, or boat; the shiur is a measure of distance, not of the time it takes to travel a parsah (מ"ב סק"). The shiur only starts after leaving the city of departure’s “ibur,” i.e., just over 70 amos outside the city (קצות השלחן סי' ס"ב דה"ש סק"ד). [Some Sephardim do not make the brachah on a trip that will take less than the amount of time it takes to walk a parsah–72 minutes (שו"ת זכרון יהודה סי' מ', שו"ת רב פעלים ח"ב יו"ד סי' מ"). If they will be returning, the time spent at the location and the return time are included in the 72 minutes. But Ashkenazim only measure the shiur by distance.]
12. In any case, if one knows he is in a dangerous area, he can say the brachah even when traveling within a parsah (מ"ב סק"). Thus, if one is passing through a dangerous area, e.g., a neighborhood of rock-throwing Arabs or other dangerous population, he can say the brachah even if the whole trip is within a parsah.
