03 April 2013

Driverless cars will affect our cities; let's not make assumptions about the sign of those changes

Meeting of the Minds | Issi Romen | How will driverless cars affect our cities?:

1. Cities will greatly expand, again: Faster and more efficient transportation will convert locations that are currently too remote for most users into feasible alternatives, abundant with space. Like suburban rail in the early twentieth century and the mass consumer automobile that followed, driverless cars will generate a gradual, but dramatic expansion of cities.

2. Buildings and parking will be uncoupled, freeing up valuable land: After dropping off passengers, driverless cars will independently seek parking (or their next car-share customers) and they will show up for the return ride at the tap of an app. As soon as driverless cars are common enough, the demand for adjacent parking will dwindle and parking lots in areas where land is sufficiently valuable will be ripe for conversion to other land use.
These two things are at odds with each other. Lowering the time and psychic cost of commuting will make outer suburbs more attractive. Lowering congestion and the amount of land focused on parking will make downtown areas more attractive. How can we be certain which will dominate?

Issi assumes the former. If I had to bet I would choose the former as well, but I would not consider it inevitable. Further, while the overall diameter of a city may increase, I expect the density within that region will be less evenly distributed that it is now. The combination of #1 and #2 may mean that the farthest suburbs are farther away, plus there are denser, smaller pockets of activity closer to the core, but there are spaces in between which are less developed than they are now.
And what about the carbon footprint, you ask? Traveling greater distances at greater speeds will require more energy. Full stop.
This is simply not true. The energy required (in the form of fuel) is the integral of the positive acceleration. This is only equivalent to the speed if you do no braking. Autonomous cars, inter-vehicle communication and intelligent roadways will all reduce the amount of braking and congestion. There is zero reason to believe the net effect on energy use will be positive.
Car sharing will not undo this in spite of reducing the total number of cars, because car sharing essentially only does away with the time cars spend parked.
Again, false. A significant portion of a car's energy is used in its construction. You conserve more energy by buying a used car than by buying a new hybrid. If car sharing results in fewer vehicles, each of which travel more miles per day total energy usage may be higher or may be lower.

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