Excellent Principles for Shared Mobility

Robin Chase, the co-founder of Zipcar, is apparently the genius behind a set of Shared Mobility Principles that came out recently.  I can’t praise them too highly.  Like the founding statements of New Urbanism, these principles cut past the noise and confusion of marketing and show what it would be like to deploy new technologies with the goal of humane and civilized urban life, not just the goal of personal convenience or profit.

Even more important, it’s been signed by many of the main players in the tech transportation field, including Uber, Lyft, Via and many others.  That means you can quote these principles back to them when their actions conflict with these ideals.

As I watch how tech marketing is sowing confusion about public transit, and damaging local officials’ ability to think about it clearly, it’s a relief to see principles such as




From these principles alone you can derive the urgent need to invest more in high-capacity fixed route services covering most of our major cities, except the most low-density or inaccessible fringes.  And the results would be something very different from what I’m seeing every day: Tech campuses built in inaccessible cul-de-sacs, or facing away from the available fixed route service, on the fantasy that in the new world everyone will use little pods that go door-to-door.

Then, when you add:


… we derive the urgent need for shared transportation to be efficient enough to scale.  Efficiency is equity.  An inefficient service will only be available to a few people, and with rare exceptions like ADA paratransit those people will be an elite.   So we can conclude that only a robust fixed route network, aimed at the “middle 80%” but not the elite, can scale to the point of being a tool for equitable liberty.

Anyway, even apart from how it relates to my own passions, this is good stuff. Read, and share, the whole thing.



18 Responses to Excellent Principles for Shared Mobility

  1. Daniel March 10, 2018 at 3:55 pm #

    This is timely. Elon Musk’s Boring Company will now prioritize pedestrians and bicyclists, something the shared mobility principles would advocate. It still uses individual pods, but it is a step in the right direction. I wonder if he eventually just starts building a true subway system.

    Perhaps you swayed him?

    • Georgist Economist March 11, 2018 at 1:56 pm #

      “Will still transport cars, but only after all personalized mass transit needs are met. It’s a matter of courtesy & fairness. If someone can’t afford a car, they should go first.”

      For one, “personalized mass transit” is a contradiction in terms.
      For another, this is the absolute worst argument for transit I’ve ever read.
      1) People don’t move by foot, bike or transit because they can’t afford cars.
      2) Transit deserves priority for geometric reasons, not because it’s a social service (see 1).
      3) Politically, the biggest result would be that the middle class people excluded from transit (see 1) would fight tooth and nail against transit. It doesn’t help that in many urban regions, many of them already drive to most destinations.

      Either Musk is an idiot, or his purpose is 3). C.f. Hyperloop: it’s a completely impractical idea that will not get implemented, but it’s a great way to antagonize CAHSR by making it look slow, expensive and “obsolete” by contrast. And as the owner of a car company, Musk is interested in it not being completed.

      • Sailor Boy March 12, 2018 at 2:56 pm #

        “1) People don’t move by foot, bike or transit because they can’t afford cars.”

        I’m glad to hear that you have never been subjected to financial constraints that have prevented you from owning a car. Many people have.

        • Wanderer March 12, 2018 at 3:54 pm #


          Back in 2009, there was an exhibit called “Without a Car in the World” at a Santa Monica art gallery. It showed photos and text from 100 car-less/car-free in the Los Angeles area. There were people who had made a voluntary decision to give up cars–most of them were fairly positive about that, about using transit etc. Then there were people who were too poor afford cars, who were generally more negative.

          Amusing side note–initially the web page for the exhibition did not include transit directions, though they did put them up.

          • Sailor Boy March 12, 2018 at 5:44 pm #

            Great link, thank you.

        • Georgist Economist March 13, 2018 at 9:42 am #

          I meant that people decide which mode to use primarily based on travel time, though certainly cost and “comfort” (cleanliness, not having to climb stairs, ability to sit down) also play a role. And to clear up a possible misunderstanding (if there is one): I can’t afford to have a car, but I wouldn’t have one even if I could afford to, because transit provides sufficient mobility. Granted, I live in Europe, where most cities are not a sprawling mess.

          • Sailor Boy March 13, 2018 at 1:19 pm #

            Thanks for the clarification :). I would agree that most choose mode based primarily on time.

  2. Georgist Economist March 11, 2018 at 1:40 pm #

    “That means you can quote these principles back to them when their actions conflict with these ideals.”

    I’m cynical enough to ask: so what? Endorsing these principles could very well be a political/marketing move. On the one hand, these companies now can point to their endorsement and have dozens of articles written about how they are the good guys for endorsing them. On the other hand, they can quote “3. WE SUPPORT THE SHARED AND EFFICIENT USE OF VEHICLES, LANES, CURBS, AND LAND.” and twist it into:
    – shared and efficient use of vehicles = carsharing, our business. It’s written straight into the green clarification box.
    – shared and efficient use of lanes = you should let our cars into the bus lane. “It looks empty and inefficient.”

    “These principles […] are designed to guide urban decision-makers and stakeholders toward the best outcomes f̶o̶r̶ ̶a̶l̶l̶ for us.”
    2. “Cities shall prioritize […] and other efficient shared mobility […]. Cities shall discourage the use of cars, single-passenger taxis, and other oversized vehicles transporting one person.” Cities shall prioritize carsharing and discourage its closest competitors.
    4. “unfolding transition to shared, zero-emission, and ultimately autonomous vehicles.” And you say this isn’t a marketing piece, Mr. Walker?
    7. “The fair share shall take the operating, maintenance and social costs into account.” Subsidize carsharing and fixed-route transit equally, please.
    10. “it is critical that all AVs are part of shared fleets, well-regulated [!], and zero emission.” Please put a high entry barrier around our sector, so that if/when AVs do arrive, only well-funded companies can threaten our market share, not ordinary people renting out their cars. If AVs were to be used primarily by and for fixed-route transit, would it need to be emphasized that they need to be shared and regulated?

  3. albaby March 12, 2018 at 7:23 am #

    ” An inefficient service will only be available to a few people, and with rare exceptions like ADA paratransit those people will be an elite. So we can conclude that only a robust fixed route network, aimed at the “middle 80%” but not the elite, can scale to the point of being a tool for equitable liberty.”

    Again, this is simply not true. In the overwhelming majority of U.S. cities, the overwhelming majority of people – including the overwhelming majority of the “middle 80%” – commute by private passenger car. Private automobile transportation is not an “elite” good, but a common good. And for the overwhelming majority of people in the overwhelming majority of U.S. cities for the overwhelming majority of their trips, travel by private passenger car will be *more efficient* than using fixed-route transit – which is one of the reasons *why* public transit has such a low mode share in most U.S. cities.

    As pointed out by Georgist Economist, you have an interesting coalition forming where the ride-share companies are collaborating with transit enthusiasts to try to erect entry barriers to keep non-fleet AV’s from competing with their business model. While that’s good for those vested incumbents (the “elite”), it’s bad for the very small minority of the “middle 80%” who don’t have access to private passenger car transport today.

    • Sailor Boy March 12, 2018 at 2:57 pm #

      “And for the overwhelming majority of people in the overwhelming majority of U.S. cities for the overwhelming majority of their trips, travel by private passenger car will be *more efficient* than using fixed-route transit – which is one of the reasons *why* public transit has such a low mode share in most U.S. cities.”

      It is only more efficient if you ignore the large cost of providing all of that infrastructure for driving.

    • RossB March 12, 2018 at 8:39 pm #

      >> And for the overwhelming majority of people in the overwhelming majority of U.S. cities for the overwhelming majority of their trips, travel by private passenger car will be *more efficient* than using fixed-route transit

      Evidence please. Seriously, show me the study. How crowded does a city have to be before fixed route trips start becoming a lot more efficient than on-demand service (otherwise known as a taxi-cab). My guess is once a town stops being called a town (but a city) you’ve already reached the point where fixed route transit is by far the cheapest way to move people.

      Are you really claiming that taxi-cabs are cheaper to operate than buses? That is absurd. The only reason that so many people drive (their own car) is because they don’t have to pay the driver.

      Take driving out of the equation and suddenly transit becomes much cheaper. It becomes the better value for the vast majority of trips because you are sharing the cost of the vehicles. Instead of buying one (relatively expensive) car, you share a bus with your neighbor. The vast majority of Americans would love to have one less “necessity” to buy, and that is what a cheaper, more efficient transit system could give them.

      • albaby March 13, 2018 at 6:54 am #

        I wasn’t talking about taxi-cabs – I was referring to people driving themselves in their own cars. It’s vastly more efficient *for them* in terms of *time* spent travelling. That’s what often gets lost in these discussions – it generally takes a lot more *time* to travel by transit in most U.S. cities than it does by car, because most U.S. cities don’t have the residential density and deeply developed CBD’s that you find in other parts of the world (or the transit-heavy American metros like NYC).

        In most cities in the U.S., transit mode share is in the low single digits – while driving is 10-20x higher. Driving is not an elite pastime reserved for only the wealthiest – it’s how the average person travels.

        The idea that we should start changing the way we design cities to prioritize the mode that a tiny minority of people use, to the detriment of the mode that the overwhelming majority of people use, may have a lot of things going for it. But it’s definitely not advancing the common person over the elite, as Jarrett sometimes posits.

      • Georgist Economist March 13, 2018 at 10:26 am #

        Not cheaper, but faster. In fact, just a few articles back Mr. Walker pointed out that the worst, least efficient fixed-route services (winding through low-density suburbs) have ~3x the boardings/hour as good demand-responsive services. The superiority of fixed-route services is obvious for two reasons: 1) once a few people are already on board, deviating for the benefit of one additional passenger wastes more time than it saves; 2) because people walk to a fixed-route service, it covers a broad swath along the route it runs, while demand-responsive services only cover a very narrow line along the route they end up traveling.

        Here is an outstandingly clear article that explains how the form of the city depends on its transportation infrastructure (don’t worry, it’s in English): http://urbankchoze.blogspot.hu/2014/02/lurbanisme-ne-peut-pas-se-dissocier-de.html Notice that the outlines are basically isochrones.

        Unfortunately, many American cities have grade-separated highways built right through them. This way, there is an enormous area of land that cars can reach. For the sake of simplicity, divide the population by the area to get the average density. As you can see, the availability of fast car travel on the highways naturally scatters the population so thinly that transit becomes nonviable.

        To make an even more pointed example, suppose that “flying cars” become affordable for a large fraction of the population. They take an enormous amount of space, sure, but because they can fly at, let’s say, 300 km/h, a half-hour flight time covers 70,000 km² or so. Even with a population of 70 million, that’s an average density of 10/ha (4/acre). That’s so low a density that it can accommodate the requirements of the flying car without problem.

        The problem comes when you try to mix different methods of transportation. If you try to run transit through suburbs built around the speed of the car (flying or not), it “asphyxiates” due to insufficient density. If you try to cram cars into the city built around transit, you get congestion, because the city is “too small”, being built into the isochrone given by lower speeds.

        • albaby March 13, 2018 at 2:03 pm #

          Indeed. While *some* U.S. metros do, in fact, have a strong core of transit-oriented development (NYC, Boston, etc.), most do not.

          One note on the urban kchoze article – that analysis doesn’t *just* rest on looking at the different methods of transportation. One of the key assumptions of the article is that the trip which is most important to people will be the trip from their residence to downtown (which is why the center of the ‘cat’s eye’ is green in all of the different formulations). That might be true in some cities – but in others, the downtown/CBD may no longer be as important an employment or business center as it used to be. If jobs and businesses are spread throughout the metro region, those isochrones look completely different.

          • Georgist Economist March 13, 2018 at 4:28 pm #

            Certainly so. And in fact, the access points of rapid links often grow into small centers in their own right. (Small green dots along the subway.) Because everybody who wants to use the link goes there to access it, there is a concentration of pass-by traffic that draws retail. In the case of rapid transit, this means a few streets full of ground-level shops (or a multiple-story indoor plaza), while in the case of highways, it means malls. A bit further, especially along the main local roads, there is still more traffic than residential uses are comfortable with, but the above-average connectivity makes that a great place for offices.

            Perhaps unfortunately, there’s a significant tendency for cities to be scattered in this manner. Imagine what happened when the walking-only city had streetcar lines built through it. Beforehand, mobility was limited by walking speed (or horse-drawn omnibus), thus the city was mostly built within the green area. Population/green area gave a rather high average density, thus multiple-story buildings were needed. To put it more simply, there was not too much land to go around, thus land was rather expensive, making it worthwhile to build like this.

            After the streetcar lines are built out, they bring much more land into reach. Because now the same floorspace for residences and offices alike can be constructed far more cheaply as greenfield development than can be bought in the existing buildings, without sacrificing mobility, the city grows outward and land prices plummet. Indeed, as long as there is unbuilt land within reach of the streetcar lines, thus new floorspace can be had for essentially the construction cost, rents collapse.

            Even once the city is built out and rents recover somewhat, the average density will be several times lower than before, thus the existing buildings in the pedestrian downtown might not be economically sustainable in their current form. If “buildings are replaced faster than the city grows”, then during each replacement, the gradually decreasing value of the land does not justify as tall (or cramped) a building as before. If “the city grows faster than buildings are replaced”, citywide low rents and the possible higher desirability of new, lower-density suburban construction easily lead to the inner city turning into a slum.

            This is compounded by the fact that new methods of transportation usually don’t appear in their fully-developed form, and initially are too expensive for at least half of society, possibly more. Streetcars and buses were a middle-class thing at first, while suburban railroads kept their upper-middle-class status even today. Steep transportation costs but virtually free land combined give an especially strong impetus towards low-density construction in the suburbs. Later this would densify as more and more people can afford the new method, unless zoning forbids that.

            The result is in some way a**-backwards. The richer half of society ends up with the longer commute times, the poorer with the shorter. Intuition would dictate that richer people, whose higher wages loosely translate into “their time is more valuable”, would be ready to pay higher rents for shorter commutes, while poorer people would rather spare money and pay with more time. This does exist, usually called “drive ’til you qualify”, but many American cities have the inversion. And it appears that gentrification can turn the situation back towards normal.

            To sum up, my opinion is that eventually cities tend to reach an equilibrium that is of a similar “shape”, with secondary centers and everything, just on a different scale. Geography permitting, they expand (or theoretically contract) in a fairly proportionate way as the speed of the dominant transportation method changes. This equilibrium state can take several decades to establish, especially if hurdles like zoning prevent rebuilding to reflect changing circumstances.
            However, I consider it possible that if ridership-oriented transit service is subsidized in perpetuity, that can hold together a dense core city built around transit even though it is surrounded by car-oriented suburbs.

          • albaby March 14, 2018 at 7:57 am #


            Interesting points – but I think there’s a simple explanation for the apparent “a**-backwards” dynamic of richer people in their cars and poorer folks on transit. It’s simply that in the U.S., travel by transit eats up more time than travel by driving for nearly all trips – so people with more means will (generally) live out in the suburbs. Even for *commuting*, trips by transit take longer than other modes – the average American who drives alone has a 25 minute commute, compared to about 45-47 minutes by transit:


            Transit is only quick if your trip ends happen to line up with a decent-speed direct route (such as living near a line that takes you to your downtown job) – but many people don’t have that even for their *commute*, much less for all their other trips.


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