One simpler way to allow cars and busses to share right of ways while still ensuring
that busses have a virtually free right of way is to use carpool lanes
and signal priority. For example, it is very rare for anywhere near 1/3 of
vehicles in a city to have more than one person. If one lane of a 3 lane arterial
was a carpool/bus lane, it is unlikely that the cars would slow down the busses
very often.

Where carpool lanes can get crowded if is they are one lane in 6,
or near the end where they merge into normal traffic. Thus, you would
have to ensure the carpool lane ended at a spot where congestion was
normally low.

Add signal priority (where approaching busses get an early or extended
green signal, depending on where they arrive), stops on the far side of
intersections, stops spaced well apart (approx. every 500m or 1/3 mile),
mostly pre-paid fares with boarding at multiple doors and proof of payment,
and you will have a pretty decent busway. In fact, cut the carpool
lane and you have a good way to run even ordinary bus lines.
(You probably also need to cut thhe signal priority in instances where
signals are timed for traffic flow, but such seems to be relatively
rare in the U.S.)

By "mostly pre-paid fares", I am thinking of how the tramways work
in Helsinki, Finaland, where you can board throuugh any door.
If you have a pre-paid ticket, you stick it in the on-board validator
after you board which stamps it. If you don't, you can still enter
at the front and pay cash for a ticket, but this costs more than
the prepaid tickets, so most people don't. This makes for faster
boarding. This could be done equally well on busses. In fact, in
Athens, Greece, all busses require pre-paid tickets, making boarding
(through 3 doors/bus) very fast.

Greg Gritton