one-way splits as symbolic transit

 Now and then I see a professional study of a transit line — often light rail or streetcar — that suggests that the two directions of service should be a little bit apart from each other, say on different streets, so that they "cover more area."

This is the clearest and simplest example I've seen of the conflict between symbolic transit and actual transit.  If you are creating transit for symbolic purposes — say, to give the appearance of permanent mobility so as to stimulate development, then it's certainly true that separating the two directions, so that rails and stops appear on two streets instead of one, will spread that appearance over a larger area.

However, if you care about people getting where they're going, the one-way split reduces the area served by a transit line.  That's because for a two-way line to be useful, you have to be able to walk to both directions of a service.  The further apart the two directions are, the smaller the area (light blue) that will have a reasonable walk to both of them.


One way split

If you're wondering whether a project is about getting people where they're going or just appearing to do so, the handling of one-way splits is often a clue. 

Obviously, one-way splits for transit are often required by a one-way street pattern, but even in these cases, when we're planning for both legibility and ease of use, planners sometimes suggest combining the two directions on one street.  This can be done by giving transit a lane that allows it to travel against the main traffic direction (called a contraflow lane), so that although traffic is split between two streets all transit is on one.  That maximizes the area actually covered by the line, but of course, it may reduce the area that has symbols of being covered! 

walkscore’s new apartment search functions

Walk Score, an admirable Seattle company that invented the "Walk Score" now widely used in the US real estate business, now has an improved app for their transit travel time tool.  That tool, which I use in my own definition of "personal mobility," shows you how far you can travel on transit from a chosen point in a fixed amount of time.  For example, here's how far you can go in 15, 30, or 60 minutes from San Francisco Civic Center, at least on agencies that participate in Google Transit:

You can find something similar at

Walkscore now has a fine new set of presentation tools that combine this information with real estate listings, so that you can search available apartments based on commute time to a destination of interest.  Couples can even search for locations that optimize both of their commutes.  For example, if one of you works in downtown Seattle and the other across the lake in downtown Bellevue, Walk Score discovers that if you want to equalize your commutes, you should live in the University District, where the blobs of access from the two workplaces overlap. Walk Score will even show you available apartments there.

2 pers commute

(Of course this service needs to be expanded beyond rentals.  Some people who are buying a home may care about similar criteria.)

All this is a step toward a more universal use of this tool that allows anyone (people, businesses, institutions, government services) to see the transit access consequences of where they choose to locate.  Many places are simply inaccessible by any efficient form of transit, so people need tools for avoiding those places if they want transit to be part of their lives, or that of their employees, customers, or clients.  That's especially important because some of these places are cheap, but may not be as cheap as they look when you consider the transport costs they impose.

I'm also interested in using this tool to generate a more factual two-digit "Transit Score" than the one Walk Score currently promotes.  More on that here.

basics: walking distance to transit

The question of walking distance in transit is much bigger than it seems.  A huge range of consequential decisions — including stop spacing, network structure, travel time, reliability standards, frequency and even mode choice — depend on assumptions about how far customers will be willing to walk.  The same issue also governs the amount of money an agency will have to spend on predictably low-ridership services that exist purely for social-service or “equity” reasons. Continue Reading →

should inaccessible employers subsidize transit?

800px-BishopRanchBldg3 Lisa Margonelli has a nice short piece in the Atlantic today on the sustainable transport achievements of Bishop Ranch, an enormous business park in suburban San Ramon east of San Francisco. 

The park was developed from farmland by Masud Mehran's Sunset Development Corporation in 1978 on the belief that San Francisco real estate would soon become expensive and companies would need cheaper space for their administrative services. His grandson, Alexander Mehran, describes the transit program as "a necessity that developed into a whole different animal." When the park started, it was simply too far from anywhere. "We were getting crushed by people going to work in Walnut Creek and Dublin," where the BART stations are. As a result, the ranch bought a fleet of buses and worked with the city and county transit agencies to subsidize both bus routes and bus passes for workers. There are now 13 different bus routes running to the park, and the connections to BART and various local train and express bus services are coordinated. On its website, the Ranch now pitches its transit program as a competitive advantage.

The most important word in that paragraph, of course, is subsidize.  Suburban business parks are expensive, per customer, for transit to serve, so a suburban employer can't expect attractive or useful service simply by demanding it.

The second most important word is cheaper, which in the suburban context is sometimes an illusion.  Bishop Ranch exists because it was perceived as a cheaper location for business.  It is, but partly because land value follows access.  The cheapest site will usually be the one with the worst transportation problems, and if a business chooses the site solely on those grounds, they're transferring the hidden cost of transportation onto their employees, their customers, and the transit agency.  Employees can quit, customers can go elsewhere, and increasingly, transit agencies, too, are pushing back against serving these cheap-because-inaccessible sites, by suggesting that employers take responsibility for some of the cost burden created by their choice of location. 

Finally, it's worth noting that Bishop Ranch is a fairly intense business park, with many multi-story buildings.  Effectively it was a single-use new town of considerable density, so while the location was difficult for transit, transit agencies still had a ridership motive in serving it.  If it were being built today, I hope Bishop Ranch would be mixed-use, with some residences mixed in, and also located with greater care in relation to existing and potential transit corridors, on the "Be on the Way" principle.  Still, for being what it is, Bishop Ranch deserves a lot of credit for taking responsiblity for the transit consequences of its site, and investing in services to help overcome those barriers.

comments of the week: ideal stop spacing is 400m?


My experiences in Leeds and Baltimore confirm the validity of a 400m standard for stop spacing. Rarely do you get to experiment with reducing or increasing stop spacing, but we can look at the sum of the experience of the two cities.

In Leeds, there have been a number of routes, normally small single-deck buses running every 30-60 minutes, that have stopped frequently and taken local roads to penetrate various neighbourhoods better than the frequent, relatively fast buses on the main arterials.

These have pretty much all disappeared with time, because people always proved willing to walk about 400m to the main arterials, which is about the furthest you're ever expected to. My experience of occasionally catching one of the slower local routes is that I would be the only passenger.

So, this demonstrates that people really are willing to walk to speed and frequency.

Meanwhile, in Baltimore, buses do stick to the main arterials. But they stop at every corner, just like the streetcars before them, which in Baltimore is about every 120 metres. And hell, are they slow – from Catonsville, MD to downtown Baltimore, I frequently spent 50 minutes to an hour to travel 8 miles that can be driven in about 20 minutes.

What's more, it's an uncomfortable ride, because the bus pulls violently to the corner at every corner, to keep the hell out of the way of traffic. And that's actually the problem with the frequent stops in Baltimore – while boarding time is a bit more complicated (though there's a fixed element to people getting up and making their way out of the bus, and people waiting for the driver's nod to start boarding), you can basically multiply the time spent waiting to pull out back into traffic by the number of stops.

So what you have is a slow service, and by that virtue, a less frequent service, because one bus can make fewer trips. So, if people will walk to speed and frequency where delivered by different routes, then we can assume that people will also walk to speed and frequency on existing routes when that's achieved by means of widely spaced stops.

In thinking about this sexless but profoundly consequential issue, you may want to refer back to this post, which clarifies the concepts of coverage gaps and duplicate coverage areas.  (See that post for more explanation of this figure.)


Balancing these two considerations is the essence of the stop spacing task.  Closer stop spacing means smaller coverage gaps but more wasteful duplication of coverage area.  So a lot depends on the local land use.  If there's more stuff along the transit corridor than in the coverage gaps, that argues for pushing stops wider.

The European HiTrans guides suggest 600m for stop spacing in busy areas where demand is high and local access is the intent.  In general, Europeans and Australians are willing to go wider than North Americans in a similar setting. 

So why on earth does any transit agency that aims to compete with cars put stops as close as 120m??  Well, these things creep up on you.  If ridership is so low that you won't be stopping at every stop anyway, close spacing doesn't present much of a problem.  But once ridership reaches the level where you're stopping at every stop, close spacing requires you to stop more, and thus run more slowly, to serve the same number of people. 

On the tradition of very-close North American spacing, John offered an interesting speculation:

"But right now, a lot of transit (in North America especially) seems designed to compete with walking, rather than with the car. Do we have the balance right?"

I think the balance is off, and I think it's largely a legacy of the streetcar era, when transit only needed to be faster than walking to draw a huge mode share. In that situation, minimizing walking distance made sense. Then the competition changed when cars came along and average trip distances increased. The streetcars were removed, but nobody ever bothered to change the stop spacing. Now transit isn't time-competitive, and in most cities it serves only the transit-dependent and niche markets like express routes to the CBD.

Is very close stop spacing on North American bus systems really so old that it predates the car, and therefore reflects the competitive situation between transit and its alternatives as it was around 1910?  That would be some sort of record for failure to adapt: a habit that has survived for an entire century after its obsolescence. 

Obviously, too, many North American services aren't trying to compete with the car; they're social services intended only for the transit dependent, and in those cases travel time is presumed to travel less.  But be careful about taking that attitude too far.

dissent of the week: stop spacing and transit’s multiple goals

Ben Smith from Toronto defends closely-spaced stops, on my post on imagining cities without mobility, which suggests the need to focus more on widely-spaced "rapid transit" stops. 

I'd like to be the devil's advocate for a minute and defend somewhat tighter stop spacing. Think of transit as an elevator: You're on the 7th floor and decide to walk up to the 8th floor, and feel that having the elevator stop there is a waste. However, someone who is getting on at the ground floor may also want to get off at the 8th floor, so having a stop there isn't a waste.

I'm not trying to say that transit should stop at everyone's doorstop, but there is a case for having a more local oriented transit with SOMEWHAT frequent stops. However, if demand and density is having your transit vehicle stop every 100m with a large number of passengers boarding at each stop, then it makes sense to use a higher-order transit vehicle with wider stops.

The easy answer to this is that if you can walk from the 7th floor to the 8th floor to get from one to the other, you can take the same walk from an express elevator that stops only at the 7th.  But that may be too easy. 

I personally am willing to walk as far to useful rapid transit (for a long trip across the region) as I will to a final destination.   My personal mode choice algorithm (as far as I understand it) is that I want to (a) minimize total travel time and also (b) get exercise and (c) avoid waiting and especially passive uncertainty.   So I'm as willing to walk the same distance to a place regardless of whether that place is my destination or I'm planning to catch rapid transit there.

Does my philosphical viewpoint on this depend too much on my own abilities and preferences?  In other words, am I assuming that secretly everyone wants to be just like me?  And if so, am I doing this more than anyone else does?

Obviously, as always, we need to recognize a portion of the population that can't walk far, but at the same time we have two widely articulated policy goals that push the other way:

  1. health goals that support encouraging people to walk if they can. 
  2. sustainability goals that require transit with highways rather than with walking and cycling, which means competing for the trip that is well beyond most people's walking distance

Those considerations lead me to a provisional view that the main prioirty for public transit investment needs to be rapid transit that's worth walking to, not slow transit that stops near everyone's door and that looks intimate and friendly in a New Urbanist mainstreet.  That was the core of my argument with Patrick Condon.

Obviously, there need to be mobility options for senior and disabled persons who have greater need for short-distance transit.  There are also other logical markets for short-distance trips where very high frequency is possible (recalling that waiting time is often the disincentive for short trips) such as downtown shuttles. 

But right now, a lot of transit (in North America especially) seems designed to compete with walking, rather than with the car.  Do we have the balance right?

UPDATE!  Ben Smith, the author of the dissent, has had an epiphany!

imagining cities without mobility

Philips Corporation, like everyone, is running a livable cities program, in this case a set of awards for individual projects rather than big-picture rankings of cities.  I just stumbled on it, and got a rude shock.

There are eight categories: Neighborhood, Mobility, Care, Education, Water, Shade, Sport, and Regeneration — all excellent things.  Obviously, I'm professionally interested in mobility, so I looked to see who was winning there. 

The leading candidate for the Mobility award is Plaza Movil Street Park, a proposal (for Buenos Aires, Argentina) for temporary street closures to create community park space.  Its benefits are described like this:

Creating recreational spaces for local communities to relax, play, meet, and chat.

That's wonderful.  It's glorious.  I'm all for it.  To use Philips's terms, it's great for Neighborhood, and probably also for Shade.  But it's not mobility

The only relationship that this plan has to mobility is that it takes space normally used for mobility and uses it for something else.

St. Augustine observed that we are always either being or becoming.  In urbanism, "being" corresponds to placehood, and "becoming" corresponds to movement or mobility.  The late 20th Century car-centered model led to the massive conversion of land area from placehood functions to mobility functions.  Transit's great virtue is that it provides a lot of mobility using relatively little space, so that more area can be devoted to places, both public and private.

And yes, a great street provides an experience that integrates placehood and mobility to a degree.  And yes, good urban redevelopment also reduces our need for mobility up to a point. 

Bravo for well-designed street closures.  But to give a street closure a mobility award seems to imply that mobility — our ability to get to places we want to go to — just no longer matters. 

There is a strong current in New Urbanism, not without detractors, that does seem interested in abolishing mobility.  Patrick Condon's idea for Vancouver, for example, would cancel a single proposed subway line and instead replace all of the city's electric trolleybuses with streetcars that go the same speed as the buses do.  He would cancel a mobility-improving project and instead spend money in way that that may do great urban things but doesn't increase mobility at all.  Once his network was complete, nobody could get anywhere any faster than they can now. 

This makes sense only in a context where going places (even under renewable elecric power) is an objective evil.  Streetcars, in this vision, supposedly cause greater urban density to be built at livable neighborhood scales, so that people meet more of their needs close to home.  People spend most of their time in their own "villages" and others nearby.  They simply do not travel far across the city, and had better not be in a hurry when they do.

It's understandable that "urban village" is a winning concept right now.  We do need to increase the self-reliance of each part of a city, so that travel demand for many of life's needs can met closer to home.  The pendulum swung far the other way in the late 20th century, toward surrendering placehood to movement.  I support and eagerly participate in efforts to help it swing back.

But I think we can see what it might look like to swing too far in the new direction.  We stay close to home, and thus evolve transport systems that are useful for going short distances and useless for going long ones.  And the obvious retort to this is:  In that case, why live in a city?  Why not just live in a country village, or in a small city? 

The whole point of living in a city is to have access to unusual things that are only possible at a large scale.  If you want major league sports or a good symphony orchestra or a world-class major university, you need to be in some kind of urban area.  If you have a very unusual interest, only a place with lots of people will have a few people who share that interest.  If you want choices, you need redundancy, also known as competition.  You need there to be two or more sources for whatever service or product or experience you're looking for, readily available from where you live.   For those things, you need a certain amount of urban mass, and some options for moving around within it.

The great irony of anti-mobility village-first thinking is that it inevitably leads to monotony — less choice and therefore less opportunity for people to form specalized communities where unusual thought and creativity can flourish.  More disturbingly, it leads to a world where only the internet offers those things, which leads in turn to nightmare images of a world of plugged-in couch potatoes, people who never go outside anymore because their social and intellectual needs simply aren't met by the 500 people who happen to be within walking distance.

The antidote to conformity and monotony is the city.  For a city to function as a city, you need mobility.  Streetcars are fun to ride, but not if you're in a hurry.  Closing a street on Sundays so people can dance is a great thing.  But you can't run an economy that way, nor can your citizens feel free. 

transit’s product: mobility or access?

This post is an important early section in the book I'm working on.  Longtime readers will recognize the primordial muck from which it arose.  I thought I would share it because it's a key conceptual marking-point and I know it will be controversial.  In brief, I argue that while "mobility" is problematic as a goal of a whole transportation system, we can't abandon it as a descriptor of transit's primary purpose and function, because to do so makes it impossible to understand how and why transit does what it does.  If anyone has a better word for what I'm calling mobility, I'd love to hear it. 


Because transit debates so often lose track of transit’s defining product – which I’ve called personal mobility – it’s worth pausing to clear some weeds around this concept.

In contemporary urbanist thinking, the world mobility is profoundly out of fashion. Todd Litman of the Victoria Transport Policy Institute defines mobility this way:

Mobility refers to the movement of people or goods. It assumes that “travel” means person- or ton-miles, “trip” means person- or freight-vehicle trip.   It assumes that any increase in travel mileage or speed benefits society. (Litman, 2008)

By this definition the output of transit that matters is passenger-miles or passenger-km.  A passenger-mile is one passenger carried for one mile.  (Ten passenger miles, for example, could mean one passenger carried for ten miles or ten passengers each carried for one mile.)

Defined this way, the concept of mobility can be misleading because it doesn’t measure how readily people got to where they were going; it just measures how far they were moved.  Most of the time, though, our travel isn’t motivated by a sheer desire for movement; it’s motivated by the need to do something – make some kind of economic or personal contact – that is too far away to walk to.

Suppose that your favorite grocery store is reachable from your house only via a circuitous bus route.  When you ride this bus to the store, you only want to go about 3 miles, but the bus takes you 5 miles in the course of getting there, and the bus company will claim to have delivered 5 passenger-miles of mobility as a result of your trip.  Obviously, that’s unfair, because you only wanted to go 3 miles. 

But really, you didn’t even want that.  What you wanted was your favorite grocery store.  You wanted access to your grocery store, not 3 miles worth of mobility.

So there are two problems with mobility, defined and measured this way.  First, it measures how far you were moved, even if some of that movement wasn’t necessary.  Second, more fundamentally, it implies that a greater good was delivered by taking you to shops three miles away than would have been delivered if the same shops were close enough to walk to. 

Transit that participates in reshaping the city, by encouraging greater density and walkability so that the basic needs of life are available with less travel, has the effect of increasing access even as it reduces our need for mobility.   From the perspective of almost all of transit’s goals, replacing long trips with short trips that achieve the same outcome is a good thing.  If shops identical to the ones you have three miles away were to open next to your house, you wouldn’t travel as far. In fact, you wouldn’t make a transit trip at all.  The bus company would lose a customer and its ridership would fall as a result.  Yet clearly, the ability to do something via a short trip rather than a long trip is better for you, better for the energy-efficiency in your city, and better for the environment. 

That’s why Litman suggests we should care more about what he calls access:

Accessibility (or just access) refers to the ability to reach desired goods, services, activities and destinations …   Access is the ultimate goal of most transportation, except a small portion of travel in which movement is an end in itself (jogging, horseback riding, pleasure drives), with no destination. This perspective assumes that there may be many ways of improving transportation, including improved mobility, improved land use accessibility (which reduce the distance between destinations), or improved mobility substitutes such as telecommunications or delivery services.  (Litman, 2008)

Mobility is how far you can go in a given time.  Access is how many useful or valuable things you can do.  If a new grocery store opens near your house, that doesn't improve your mobility but it does improve your access.  You can now get your groceries closer to home, so you don't need as much mobility as you did before.  You can also improve your access by working at home instead of commuting, downloading music instead of going to a CD store, and moving in with your romantic partner.  In other words, a lot of the work of access is simply about eliminating the need to move your body around the city in order to complete the economic and personal transactions that make up a happy life.

But before we dismiss mobility as a distraction, let’s look again at the three ways of improving access, as Litman lists them:

  • “Improved mobility”
  • “Improved land use accessibility (which reduces the distance between destinations)”
  • “improved mobility substitutes such as telecommunications or delivery services”

When I say that transit’s product is personal mobility, I’m emphasizing the first of these three ways of improving access.  I’m not implying that the others are unimportant, only that the first of these – improving access by improving mobility – is transit’s primary job, just as firefighting is the fire company’s primary job.

Transit does have side effects, though, that affect the second kind of access, and we’ll return to these in Part II.  If an especially popular or exciting form of transit, such a streetcar or monorail, is built in an area, this may raise the land value of the area in a way that encourages denser development, and denser development often improves access by putting shops and other destinations that you value closer to your house. 

Designing transit to trigger desirable development is one of the core ideas of the New Urbanism, but like many new ideas it’s really an old one.  In 1900, when public transit was the primary form of urban transport for distances too far to walk, the public transit infrastructure determined the shape of the city’s growth.  In fact, many transit lines were created and owned by developers whose real goal was to build and sell houses along the line.

So transit can improve access two ways: (a) by providing personal mobility and (b) by influencing development to create denser communities where less mobility is required to do the same things. 

The second of these, however, is obviously an indirect impact.  Transit may lead to access-improving development, but only via several intermediate and unreliable steps.  You can build a rapid transit line and still not get more density if several other things don’t fall into place – including zoning, economic growth, cooperative neighbors, and bankers willing to lend to developers.  In that case, the new transit project doesn’t improve access at all, unless it has improved the first kind of access: mobility.

What is more, the ability of transit to stimulate development is clearly related to how well that transit seems to promise good mobility to the people who will live, work, or play there.  We don’t pay more for an apartment over a transit station because the station is a nice community amenity, like brick paving and planter boxes.  A transit station adds value to development precisely because buyers think it will make it easier for them, or their tenants, to get around.  So if transit isn’t credible in offering mobility, or at least appearing to do so, it’s unlikely to stimulate development.

In 2009, we began to see web-based tools that allow you to enter an address and see where you can go, in a fixed amount of time, from that address.  Here, for example, is the output from's travel time tool, when queried by someone near the San Francisco Civic Center at 9:00 AM:

 GoogEarth walkscore

These tools aren’t for planning a trip, they’re for visualizing your freedom.  Not your freedom in some improved city of the future, but your freedom now.  That’s what mobility is: your freedom to move right now.

But the genius of these tools is that they let us see how choices we might make would affect that freedom.  Imagine that you’re deciding where in a city to live.  For each house or apartment you’re considering, you can check one of these sites and see quickly where you’ll be able to get to easily on transit.  And you won't get just an abstract "transit score."  You can look at this map and see how easy it will be to get to the places that matter to you.

The tool might save you a fortune.  If you’ve decided that you can only afford a house in a distant suburb, enter that address and you’ll get a clear map of just how far away things that you care about will be.  You might run the numbers on the cost of commuting and decide you’ll save money by spending more to live in a better location, closer to rapid transit and/or closer to the city, where you’ll spend less on transportation. 

In other words, you might make a decision that requires less mobility, because it has better access.  That access will consist not just in being closer to things you value, but also in having better transit options for the trips that are still too far to walk or cycle.

Mobility and access aren’t opposites, and mobility isn’t some tired doctrine worshipped only by blinkered traffic engineers.  If we want cities to be built in ways that require less travel, cities with better access, we will do that by ensuring that those cities still have generous transit mobility.  We need to show that if you locate in a transit-intensive place, you will be able to get to lots of places that matter to you, on transit; indeed, that you’ll have full access to all the riches of your city, or at least those that you care about. 

So in a book on transit, I’m going to insist, unfashionably, that in the transit business mobility is still our primary product.  Mobility is only one dimension of access.  The other two, as Litman defines them, are urban redevelopment and telecommunications, both of which can reduce the need for travel.  But mobility is the kind of access that most people expect transit, in particular, to deliver.

One of the major hazards of urban planning is that planners and theorists can get so excited by their visions of the future that they lose track of the present.  We can imagine futures in which transit systems help us to build denser cities, where we can have more access because things are closer.  But if we want today’s voters to support our vision, we have to care equally about what their needs are right now. 

In the short term, most of us are stuck with the current geography of our lives.  Our homes, jobs, relatives, friends, and favorite shops are wherever they are, and we’ve accepted, consciously or not, the need to travel the distances between these important things.  We can try to relocate some of these things in the months or years ahead, but we can’t relocate any of them today. 

This book will look more at urban form and all the ways we can change it, but we can’t use transit to create better cities unless we first understand how transit does its primary task of providing mobility.  Meanwhile, though, transit needs to focus on the shorter-term perspective: the perspective of someone who needs to go somewhere, and get there soon, to address a need that they have right now.  This person isn’t thinking about how better transit might help transform her city.  She’s thinking: “I just need to be there!”  We need to figure out whether transit can help her, and if so, how.

“Mapnificent”: Your Freedom to Roam

Long ago I highlighted an early product by which enabled you to select a location and time of day, and then showed you a map of all the places you can get to on transit within a specified time.  Reader Tom West points me to a new effort along similar lines, called Mapnificent, by Stefan Wehrmeyer.  He describes the product on his blog in both geeky and practical detail. Continue Reading →

Transit’s Role in “Sprawl Repair”

Duany Plater-Zyberk, one of the leading planning firms associated with New Urbanism, is thinking about “sprawl repair,” a process by which utterly car-dependent landscapes could be transformed into something more walkable, and thus more resilient.  Galina Tachieva of DPZ has an article explaining the concept at Planetizen.  Continue Reading →