It occurs to me that given an area with a lot of existing horse stables and a better design - one incorporating a lithium battery bank and/or a large flywheel (so the horses can keep a steady pace even while stopped at intersections and loading/unloading) - this could actually be a viable way to power a commuter bus. Of course, such a bus would need to be a double-decker, with the horses on the lower deck (in walk-through stalls perpendicular to the axis of movement) and passengers on the upper deck.

But it would be doable. And you could even cover the horse level with those one-way paint schemes that some buses use, except reversed: this would let the horses be seen (to attract both ridership and increased viewership for the ads covering the passenger deck exterior) but keep *them* from seeing out and thus undisturbed by traffic.