Couple months ago I saw this concept. It was really futuristic and seems like a solution for megapolis , but as many ideas it was too overbold for the reality of old cities with narrow streets and mix of car types on the road.
But today… Look at this. This is a real bus!
Here is more photos: http://www.theverge.com/2016/8/2/12360620/china-TEB-elevated-straddling-bus-unveiled