The https://Salat%20//www.al-feqh.com/en/salat-of-those-with-excuses-recognized-by-the-sharia" rel="nofollow - Salat of a traveler in a bus

1- If it is a supererogatory Salat:

Generally, supererogatory Salat observed in any way, with or without an excuse not to pray it as it has been prescribed, is valid. This is due to an authentic narration that: The Messenger of Allah ﷺ used to observe supererogatory Salat on his rides (camel) in whichever direction it faced.[ Source: An-Nasaai.]

2- If it is an obligatory https://www.al-feqh.com/en/salat-of-those-with-excuses-recognized-by-the-sharia" rel="nofollow - Salat :

The Salat is valid if the person is not able to dismount and pray on the ground, or will be unable to mount back on his ride due to dismounting, or he fears the harm of an enemy or due to other related reasons. This, however, may occur in several different forms, which include:

1- That he is capable of facing the direction of the Qiblah, and of bowing and prostration, as is the case if he is in a ship. It is then compulsory for him to observe the Salat in its usual form. This is because he is capable of doing so.

2-That he is capable of facing the direction of the Qiblah, but unable to bow or prostrate. It is then compulsory for him to face the Qiblah during the initiating Takbeer. Thereafter, he prays to any direction the bus faces, gesturing for both the bowing and prostration.

source: https://www.al-feqh.com/en