Maran the Shulchan Aruch (Orach Chaim 90:16) ruled that the measure of time along one’s planned direction of travel—meaning on his way to work or home—is four mil, which equates to a 72-minute journey. Conversely, if he must travel backward, creating a delay on his journey, the obligation is up to 18 minutes. However, this applies specifically when traveling by private vehicle and not via public transportation, which might cause him to miss the proper prayer time (Ktzos HaShulchan 13:2). Furthermore, if there is apprehension of danger on the roads, it is prohibited to travel for a minyan (Mishnah Berurah 90, sub-commentary 52; Shevet HaLevi, Part 8, Siman 19). Likewise, in a situation involving financial loss, one is not obligated to travel to pray with a minyan (Mishnah Berurah).