One thing that seems to have not been addressed here is noise. I was just on a quick walk in downtown Sydney, Australia. It was so loud on the sidewalks, with buses seeming to contribute a huge portion of noise. Additionally, the diesel exhaust can be stifling particularly in these urban corridor situations where the buildings trap the fumes. I would much rather be walking next to 50 Prius/Camry taxi cabs and a few private vehicles than 10 loud buses. I agree with the idea of bus utilization in cities but there are certainly some downsides.