The idea: Single-person zorbs plus rail lines (six, four for the ball to roll on and two above to keep a high wind from lifting the zorb up and out). Your Friendly Local Government sets up the lines.
When you arrive at the 'departure' station, you climb in the zorb and pay a fare to use the elevator,
which lifts you and the zorb up to the 'takeoff ramp'. After being pushed off the ramp, a steep 60 degrees to build up speed, your zorb is launched down the lines.
Naturally, the lines are on an angle -- a gentle angle, but an angle nonetheless -- and you zoom off on your way, through the air and above the city. After the initial energy is spent to get the ball up, you don't spend any energy on gas or propulsion -- just tumble a little. The effect is not unlike being in a pinball in a habitrail.
Once you arrive at your destination, you hit a 'cooloff' ramp of gravel, sand, shredded rubber, or other such high-friction substance. Handlers help you out, and roll the zorbs over to the elevators, to pick up their next passenger.
The one problem with the Zorbway: Once you get to work or school, there's no getting around looking like you just got your clothes out of the dryer, since in effect, *you* just got out of the dryer.