In the Name of God, the Most High
If a person travels a distance of one day journey by means of public transportation or the total of outward and return journey is just the same distance, the traveler should shorten his prayers and break his fast. This is mandatory.
The distance covered at a time differs from vehicle to vehicle, from one means of transportation to another depending on their type and qualities. In the past, caravans were considered to be means of public transportation. The distance i.e. one day of journey was equal to eight farsakhs (about 45 kilometers). Now that buses are the regular means of transportation the distance that must be travelled is equal to 700 kilometers.