The words on the back of these trucks, and versions of this expression are, in English, on every single truck:
1 Blow Horn
2 Horn Please
One of the guidebooks expressed it thus – in India they use horns instead of brakes.
This is a two-lane road. One truck is passing another. See that oncoming bus? I forget which of these vehicles ended up in the dirt but this is one of the reasons, I’m sure, that the dust is everywhere so thick in the air.