Question: Why is there no standing on the upper deck of the bus? 

Answer: If more people stand on the upper deck then on the lower deck, there is a risk of the bus toppling over. The reason is that when there are more people standing on the upper deck, the center of gravity of the bus will be raised and this will make the bus unstable and there is a chance that the bus can be toppled over when it turns or something like that....
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