Transit activists are constantly besieged by a long list of wondrous new technologies that are going to change transportation forever, meaning that all this time we're spending on buses and trains and bicycles is just going to be a waste when the electric car / podcars / Google cars save the world and make all of that obsolete. Implicit in this criticism is, of course, the idea that somehow existing transit technologies aren't up to the task of swaying people from their undying love for the automobile, but we'll save that for another post. The trouble is that none of these new technological advancements is going to address the fundamental issues underlying why cars are bad for our society. But, since all of my generally progressive and environmentally-conscious friends are talking about driverless cars lately, maybe it would help if I laid out what those fundamental issues are, and in doing so demonstrated why transit and urbanism is a much better bet than hoping for some new technology to transform our transportation system.
Of course, the biggest danger of our auto-centric transportation system is climate change. Climate change is caused by the release of carbon dioxide (and other, more problematic but less prevalent greenhouse gases) into the atmosphere, usually as a byproduct of combustion energy generation. Cars are a huge source of carbon dioxide emissions, with their gasoline-burning engines, but other types of combustion-based energy generation, such as coal- and gas-fired power plants, are also an issue.
To stop climate change, then, it is not enough to simply switch cars from gasoline to another energy source (like electricity, hydrogen, compressed air, etc.-- which are all electrically-derived, as I cover here). We need to also ensure that the electricity is initially generated from a renewable source as well-- and, since we also need to power everything else in our society from renewables, and they are currently a very minor contribution to our electrical grid, the more energy-efficient our transportation system gets, the more likely it can be carbon-neutral.
This, of course, is where transit excels, and where most of these new technologies fail. Any technology, be it an alternative-fueled car, a personal rapid transit pod, or a driverless taxi, that involves hauling around a metric ton or two of metal per passenger or small group of passengers is inherently energy-inefficient. A small, 1,000kg car with the usual load of 2 passengers in it has to transport 500kg of car for every passenger. For a fully-loaded city bus, that ratio is closer to 150kg of bus per passenger. Rail vehicles, with lighter electric motors, no fuel tanks, minimal suspension, and significantly greater capacity, can obviously be even more efficient. It is therefore a fact of physics that a well-used public transit vehicle (which they all will be, in the glorious car-free utopia) will always be more energy-efficient than a private car. Electric cars, hydrogen cars, and even platooned driverless cars will be more energy-efficient than the present auto fleet, but they won't be efficient enough, and they certainly don't represent the best way to go about transforming our society.
Sprawl is a form of living in which densities are low and places that you'd like to go are far apart from each other. Sprawl is bad for people because it breeds obesity and social isolation; is bad for our society because it requires a lot of infrastructure due to the distances between things, while at the same time not generating enough value through taxation to pay for that infrastructure; and is bad for the environment because we keep paving over wilderness and farmland, among a whole host of other reasons. Sprawl is the ultimate enemy of the urbanist. Sprawl was essentially enabled by the automobile (although streetcar suburbs were a kind of walkable proto-sprawl), and sprawl makes modes other than the automobile impractical. Sprawl is environmentally awful, energy-inefficient, and generally unpleasant for many who live there. It's also dramatically oversupplied-- surveys show that many people, and most young people, would like to live in denser, more walkable, more transit-friendly neighborhoods, but those neighborhoods are incredibly expensive because they are incredibly rare. Sprawl has also woven itself into the fabric of city planning-- zoning codes across this country are written in such a way that they basically preclude the construction of anything but sprawl, even in dense cities.
Cars create and enable sprawl for many reasons. One of them is parking-- the giant parking lots, attached garages, and parking structures that we build in which to store our cars are like spacers inserted in the machinery of the city, spreading things out from one another. They also make walking, cycling and transit-riding harder-- you're a lot less likely to shop by foot or transit if you have to cross a massive and desolate stretch of asphalt, randomly populated by distracted drivers searching for a parking space, in order to get to the store. (I'm looking at you, Victoria Gardens.) Wide roads and freeways have a similar effect-- built to accommodate traffic, they end up encouraging the same. (PRT and some sort of driverless car-taxi system, admittedly, wouldn't depend on huge parking lots at every destination, although the driverless car-taxis would need to be parked somewhere.)
That said, probably the most significant reason that cars promote sprawl is that they are so damned good at their job. The car is a tool that allows its owner to make a trip of essentially indeterminate length, at any time, at astonishingly high speeds. (The two-three days it takes to cross North America in a car may seem agonizing today, compared to the 6 hours it takes in an airplane, but there was a time when that journey took 5 months and included a significant likelihood of death.) The modern automobile transportation system allows those of us who live in the developed world to think of a 100+km daily commute as a normal fact of daily life, and to think little of coming home from that commute only to visit a restaurant three towns over. That sort of mobility allows for sprawl-- if you can travel a dozen kilometers on a whim, everything can be dozens of kilometers apart.
Paradoxically, when we have less mobility, we have more access. In Manhattan, where even the subways run at an average of 28km/h (the expresses manage roughly 40), and the old joke is that driving across the island at rush hour is impossible, the incentive is to pack everything closely together so that you don't need speed to get around. Once everything isn't so spaced out (ie, is denser), a life based on transit and active transport becomes a matter of course. Any form of vehicle that allows nearly infinite mobility at the press of a button, driven or driverless, gasoline or otherwise, will continue to enable and exacerbate sprawl.
Closely related to the problem of sprawl is the problem of urban space. In Sprawlsville, land is cheap, so space isn't really an issue, but in dense cities, space is at a premium. We have to decide how to allocate that space, and at present, we allocate a lot of it to cars, making it harder for people there to walk, cycle, or ride transit. The problem of space efficiency is caused by the same thing as that of energy efficiency-- the idea that each person or small party should have their own, dedicated metal box surrounding them. For the same amount of people who all want to go somewhere, transit is the most space-efficient mode to get them there, followed by walking, then cycling, then some sort of platooned individual transit method (like PRT or communicative driverless cars), then automobiles. See, for example, this photo. You can, of course, add the concern of parking space for cars (and, to a lesser extent, bikes). In places where there are a lot of people, all of whom want to travel, and not much space, transit is simply the best way to move them-- and cars are a guaranteed recipe for congestion.
Toss on top of all of that the fact that our infrastructure is already overcrowded, even with providing nearly all of our urban public space to cars. Building new infrastructure in many areas is going to involve tunneling or elevated structure, in many others will involve buying and destroying other properties, and all around will be exceedingly expensive. Driverless cars may alleviate this problem somewhat, if we could get relatively universal adoption and sufficient communication to allow for platoons or very short following distances. PRT is likely to involve its own massive infrastructure project, for minimal benefit.
Problems of Roads
Roads and road vehicles have a bunch of ancillary environmental problems that come with them. They bisect habitat where they are built through rural and wilderness areas. They tend to slough off rainwater, rather than allowing it to percolate into the ground. Road runoff is generally contaminated with tiny rubber particles and various sorts of lubricants and other fluids that leak out of cars-- and that will still be necessary in any new-tech vehicle. If vehicles on them are moving at any appreciable speed, they can be expected to injure or kill pedestrians and cyclists, or at the very least make it hard for folks using active transport to get across. Any car that drives on the roads will have these problems, and driverless cars may even exacerbate some of them (eg. roads may get faster, and therefore even harder to cross as a pedestrian).
Problems of Non-drivers
Any driven car will need to be driven by somebody. That still isolates children, the elderly, the disabled, and likely the poor from mobility. PRT doesn't have this problem. We will need a nearly universal shared driverless car network before they solve this problem for the poor.
Problems of Social Isolation
I believe, based on admittedly scant evidence, that much of our society's lack of compassion is at least contributed to by social isolation, borne of our suburban mode of living. In a walkable, urban environment, or on public transit, one will bump in to people from all social strata, ages, ethnicities, sexual orientations, gender presentations, and yes, states of mental health. When you live in suburbia, and can easily drive from your attached garage to the parking lot at your job, you are effectively insulated from anyone you don't actively choose to associate with. This has to have profound implications on how you perceive the world around you. All of the wondrous transit-obsoleting technologies that I've mentioned still revolve around the idea that we will continue to be able to shut out the outside world while moving through it.
Besides, public transit appears to be the place for spotting that special someone, at least going by Cragislist's "missed connections" section, and at least if you're in the Northeast, Northwest or Chicagoland.
There is no technology that will allow us to continue on as we are now-- in our own private little boxes, sealed up from the world around us, as we make our way between point A and point B in our lives-- that will also allow us to mitigate the profound damage we are inflicting upon our world. There cannot be-- such a technology is a physical and geometric impossibility. The longer we wait for such a thing, the harder the transition to a new way of moving about our world will become, and the less able we will be to hold on to the high quality of life to which we are accustomed.
As I have said since I started this blog, we have the technology to transform our transportation system. We have had it for a hundred years. It begins with the bicycle, and moves upward through the electric trolleybus and light rail train, through the subway and commuter train, to the long-distance and high-speed rail systems that we are only now thinking about rebuilding. If we can simultaneously build out our nation's renewable energy grid, we can begin to move into a society where we will lose our cars, yes, but we will gain happier, healthier lives.
And if we can't... well, I'm going to miss Miami.