Core Viewpoint - During the summer transportation period, the average daily passenger volume of the national railway exceeds 10 million, leading to changes in train numbers that may affect travelers' itineraries [1] Group 1: Train Number Changes - Train number changes are related to the "upward and downward" direction of trains, particularly at junction stations where train directions may change [5][9] - For example, the G3336 train from Fuzhou to Changsha South changes to G3333 at Nanchang West Station due to a change in travel direction [9] - Train number changes can occur multiple times during a journey, and are not limited to long-distance trains [9][11] Group 2: Train Number Display and Passenger Impact - The train number displayed on tickets only shows the departure station's train number, while changes during the journey are not reflected on the ticket [13] - Passengers can check for train number changes using the 12306 App, which provides real-time updates on train schedules [13] - Despite changes in train numbers, passenger seating arrangements remain unaffected, and onboard staff remain the same [14][16]