Reminder - Robocars aren't PRT

A pair of thoughtful pieces on driverless cars (Driving Sideways, NY Times, 7/23; How will the driverless car affect the design of our cities? Treehugger, 7/25) are a welcome contribution to the discussion of the problematic nature of 'robocars.'

However the small size of pod transit (PRT) vehicles still serves to confuse them with driverless cars in the minds of many.

So let's reacquaint ourselves with what pod transit is and is not (chiefly):

• Pods are shared public transit vehicles, you won't own one like you'd own a driverless car. You'd use pods like you'd take a train or ride a skyscraper elevator.

• Pods run on rails/guideways/guidepaths shared only with other pods, there is no danger of pods hitting cars or pedestrians (under expected operational and emergency conditions).

• Pods don't stop at any old place, they only serve pod stations which would be sited according to the local public planning process. Pod stations could anchor dense mixed use TODs or urban villages, whether new or preexisting.

The point being that if a district is below a ridership/revenue threshold, below which light rail or subway would not be financially viable, it might be viable for pods which would have lower capital and operating costs. Applied community wide, PRT in the transit toolbox would mean more rail transit available to more people and places.

Whereas driverless cars -- in offering the possibility of less congestion, safety (for occupants) and easier commuting (quality time with our smartphones) -- would lessen the perceived urgency of stopping sprawl and ending car culture.