Originally Posted by rdrnek3
I didn't realize that it actually attached to the floor! But I had a feeling that it must be structural if everyone left it on. Thank you for confirming my suspicions.
It does depend on the bus (which you can indicate to users by going to User CP in the upper left and entering your details). A few buses (they seem to be all the van-style) have a chair rail that does not extend all the way to the floor, but is just bolted/riveted/screwed to the inside of the ribs. These are possibly "structural" in the sense of something that helps keep the body intact in a collision, but they don't play a role in attaching the walls to the floor. The chair rails in the larger buses like what I'm describing are "structural" in the sense of actually holding the bus together during normal operation, but also structural in a resistance to collision sense - they're an extremely ingenious and lightweight (not to mention inexpensive) mechanism for spreading out the force of a side impact and ensuring that the walls basically can't possibly separate from the floor in that situation.