Economists do it with models. Mental models. Mental models that fall to pieces the moment they are faced with the cold light of reality. - Me
The only problem with this proposed bus is that some bunch of idiots will park half on and half off the sidewalk like usual. Then the cars will get stuck in the wheels.
Still it's impressive they reached the testing stage so quickly. We only saw the first pictures of it in the spring.
Hopefully the thing doesn't fall over and explode either. And yeah, keeping the rails clear for the bus might just be the achilles heel of the whole project, but I'd expect engineers to work out some sort of fix for that sort of thing.