since 1 october 2003, passengers who are taking z99b/100b cannot disembark the train at the stops listed above, as all travelers to hong kong from shanghai clear chinese immigration and customs at shanghai station, and once they have done so they are considered to have left mainland china and are no longer permitted to leave the train until their arrival at hung hom station. the same rule also applies to northbound travelers who will clear chinese immigration once they have arrived at shanghai station. 144-hour visa-free transit for passengers who are of selected nationalities are available since 30 january 2016.