He may be a brilliant visionary in all kinds of ways, but Elon Musk’s “Master Plan, Part Deux” makes grand plans for the abolition of fixed route public transport without thinking clearly about urban space:

“With the advent of autonomy, it will probably make sense to shrink the size of buses and transition the role of bus driver to that of fleet manager. Traffic congestion would improve due to increased passenger areal density by eliminating the center aisle and putting seats where there are currently entryways, and matching acceleration and braking to other vehicles, thus avoiding the inertial impedance to smooth traffic flow of traditional heavy buses.

“It would also take people all the way to their destination. Fixed summon buttons at existing bus stops would serve those who don’t have a phone. Design accommodates wheelchairs, strollers and bikes.”

Musk assumes that public transit is an engineering problem, about vehicle design and technology.  In fact, providing cost-effective and liberating transportation in cities requires solving a geometry problem, and he’s not even seeing it.  What’s more, he’s repeating a very common delusion, one I hear all the time in urbanist and technology circles.

Musk’s vision is fine for low-density outer suburbia and rural areas.  But when we get to dense cities, where big transit vehicles are carrying huge ridership, Musk’s vision is a disaster.  That’s because it takes lots of people out of big transit vehicles and puts them into small ones, which increases the total number of vehicles on the road at any time.  The technical measure of this is Vehicle Miles (or KM) Travelled (VMT).

Today, increasing VMT would mean increased emissions and increased road carnage. But let’s say technology has solved those problems, with electric vehicles and automation.  Those are engineering problems.  Inventors can work on those.

There is still, and will always be, the problem of space. Increasing VMT means that you are taking more space to move the same number of people. This may be fine in low-density and rural areas, where there’s lots of space per person.  But a city, by definition, has little space per person, so the efficient use of space is the core problem of urban transportation.

The tyranny of maths

When we are talking about space, we are talking about geometry, not engineering, and technology never changes geometry.  You must solve a problem spatially before you have really solved it.

The reigning fantasy of Musk’s argument is that we must always “take people all the way to their destination”. But to do this we must abolish the need to ever change vehicles – from a train to a bus, from a car to a train, from a bus to a bike – and of course we also abolish walking.  This implies a vision in which buses are shrunk into something like taxis, because a vehicle going directly from your exact origin to your exact destination at your chosen time won’t be useful to many people other than you.

So a bus with 60 people on it today is blown apart into, what, little driverless vans with an average of three each, a 20-fold increase in the number of vehicles?  It doesn’t matter if they’re electric or driverless.  Where will they all fit in the urban street?  And when they take over, what room will be left for wider sidewalks, bike lanes, pocket parks, or indeed anything but a vast river of vehicles?

There are audiences for which Musk’s vision makes mathematical sense sense: people for whom useful high-ridership transit isn’t an option anyway.  There are two big categories of these people:

  • People who live in outer-suburban and rural areas, where space is abundant and high-ridership transit isn’t viable;
  • The top 20 per cent or so of urban residents, who can afford to use relatively expensive servies that would never scale to the entire population of the city.

If you are in one of these categories, your most urgent task is to remember that most people aren’t like you, and that cities are impossible if everyone lives according to your personal tastes.  As Edward Glaser said, “one’s own tastes are rarely a sound basis for public policy”.

That issue, right there, is the great disconnect between tech marketing and genuine urban problem-solving.

Tech marketing is all about appealing to elite personal tastes.  It runs on the assumption that whatever we sell to the wealthy today we can sell to the masses tomorrow.  

But some things stop working when everybody buys them. Cars in dense cities, for example, are not a problem when only the top 20 per cent are using them; it’s mass adoption of cars that makes them ruinous to a dense city and to the liberty of its citizens. Ask anyone in a fast-growing developing world city about that.

Here is the harm that this all this elite chatter about abolishing the bus is doing: it’s introducing fatal confusion into the discussion of urban development.

The density solution

Dense cities that want to live in the real world of space and time, and that do not want to become dystopias that are functional only for the rich, need to use urban space efficiently. There is some simple and well-proven maths about how to do this, which is also the maths of how transit systems achieve high ridership.

These cities need to organize themselves around frequent transit corridors, where big-vehicle frequent transit, bus or rail, can prosper, allowing the city to grow dense without growing vehicle trips.

Someday some of these corridors will be rail or Bus Rapid Transit. But the only way to grow enough corridors quickly, so that you cover much of the city with frequent service that can succeed in ridership terms, is to take frequent fixed-route bus service seriously. If you don’t do that in your land use planning, you’re going to end up building a city where fixed transit is geometrically impossible, and then you’ll have to settle for Musk’s vision. Geometrically, that vision can only mean liberating transportation just for the top 20 per cent – or electrified, automated gridlock for everyone.

Smart cities aren’t just the ones that chase the latest technology fads. They’re the ones that think carefully about the spatial, geometric problem that a dense city is. Because if it doesn’t work geometrically, it doesn’t work.

Jarrett Walker is an international consultant in public transit network design and policy, based in Portland, Oregon. He is also the author of “Human Transit: How clearer thinking about public transit can enrich our communities and our lives“.

This article was originally written for his blog, and is reposted here with permission.