Two different readers forwarded me links to this train/bus hybrid vehicle being introduced by JR Hokkaido. On of them was Adron, who blogged about it at his site.
So it seems to me that we now have a variety of design choices for transit system, divided along several dimensions:
Dedicated right-of-way (e.g., LRT, BRT) versus operation in traffic (Streetcar, Bus).
Fixed guideway (rails, catenary wires, dedicated busway) versus re-routability, either temporarily (around congestion) or permanently (re-routing to respond to changes in demand).
Electric versus hydrocarbons (and hybrids thereof).
This particular vehicle blurs all the boundaries, but it seems to me that the design questions remain:
When do we used fixed guideways as a place-making tool?
When do invest in dedicated right-of-way so that transit can avoid traffic congestion?
When do we use self-powered vehicles versus those dependent on a catenary system?
I think I’m getting a headache :-)