Meditations

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

Posted on April 11, 2011 in Access, Meditations, Stop Spacing

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

Posted on April 10, 2011 in Access, Dissents, Meditations, Philosophy, Stop Spacing

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:

health goals that support encouraging people to walk if they can.
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!

on “category errors”

Posted on March 23, 2011 in Meditations, Philosophy

From a chapter of my book called "Five Paths to Confusion," which discusses common errors in thinking about transit. I hope that somewhere out there is a logician or linguist or philosopher who can suggest a better term for "category error."

A category error occurs when you think about a spectrum as though it were a series of boxlike categories. If you and a friend disagree about whether something is blue or purple, you’re making this error together. Blue and purple are adjacent zones on a continuous spectrum of colors (technically wavelengths of light) and zones on a spectrum can only have fuzzy or arbitrary edges. So if you disagree about whether something is blue or purple, you can both be right, based on slightly different notions of where you mark the boundary in the fuzzy area where blue shades into purple. If one of you is right and the other wrong, it can only be because of some arbitrary standard about where blue ends and purple begins, a standard you’ve both agreed to respect.

Category errors are built into the very structure of our language. Our category words feel like boxes with hard edges: blue, purple, tall, wealthy. But like colors, most of them really refer to directions or zones on a continuous spectrum. There’s no objective basis for saying “Jim is tall,” unless we just mean “Jim is taller than most people.” “Tall” is not a box; it’s just a range or direction on a spectrum of possible heights. We all know that, and for simple ideas like height or color the category error rarely causes trouble.

But when we talk about emotive categories, such as wealth or success, we can easily lose sight of the spectrum, and as with blue and purple, this can cause pointless arguments. Consider a famous comment widely (if falsely) attributed to British Prime Minister Margaret Thatcher: “A man who, beyond the age of 26, finds himself on a bus can count himself as a failure.” Stated that way, “a failure” sounds like a box that you’re either in or out of. Associating buses with failure or poverty is a common attitude in some cities. If you think about failure or poverty as a box, this can be an easy way to decide that buses aren’t worth your attention, and that there’s no point in thinking about how buses and rail transit can work together as one network.

But even if it’s true that bus riders are poorer than rail riders on average, you can change your perspective by reminding yourself that the boundaries of “poor” and “middle class” and “wealthy” are as fuzzy or arbitrary as the boundary between blue and purple.

Some category errors are built into transportation planning jargon. For example, you may hear certain planners divide transit riders into two boxes. One box, called a discretionary or choice rider, contains people who have the option of driving, and who will use transit only if it out-competes their car. In the other box is the transit dependent or captive rider, who has no viable alternative and therefore has to use transit. Dividing up riders this way leads to the idea that transit must compete for choice riders, while captive riders can largely be taken for granted; they will ride no matter how poor the service gets.

These categories are imposed on reality, not derived from it. Transit dependence, like wealth itself, is a spectrum, with vast numbers of people in the grey areas between “choice” and “captive.” For example, many people with low incomes own a car out of necessity, but experience owning a car as a financial burden. Many low-income families feel they have no alternative but to own a car for every adult in the house. If we give these people credible alternatives to car ownership, they can experience the result as liberating, even though some transportation planners will now call them captives. Often they will find better things to spend that money on, such as education. Many people are in situations like these, and we can achieve both environmental and social goods by helping them choose to own fewer cars. The two-box model of society, where everyone is either choice or captive, prevents us from seeing those possibilities.

Very few of our category words describe things that are really boxlike categories. So whenever you hear someone divide people into two categories, it's worth asking, "are these really boxes, or just zones or directions on a spectrum?"

rail-bus differences: premise or conclusion?

Posted on March 3, 2011 in Bus Rapid Transit, Meditations, Rail Transit, Streetcars (Trams), Technophilia

When you think about transit technologies, how do you categorize them? And why?

Have a look at this first table, which sorts services according to the exclusivity of their right of way. The terms Class A, B, and C are from Vukan Vuchic, describing the basic categories of "what can get in the way" of a transit service.

Is this table two rows, each divided into three columns? Or three columns, each with two rows? Which distinction is more fundamental, and which is secondary?

Right-of-Way Class vs Rail-Bus Distinction

Class A

Exclusive right-of-way and separated from cross traffic

Class B

Exclusive right-of-way, NOT separated from cross traffic.

Class C

Mixed with traffic, including mixed with pedestrians.

Rail

Most rail rapid transit, using “third rail” power sources. Most classic “subway” and “metro” systems.

Most “light rail” in surface operations. Parts of some European and Australian tram networks.

Most North American streetcars. Many European and Australian trams.

Bus

Separated busways: (Brisbane, Ottawa, Bogotá, and segments in Los Angeles, Pittsburgh) Freeway bus/HOT lanes.

At-grade busways: Los Angeles Orange Line, Western Sydney busways, etc.

Buses in mixed traffic.

Well, if your objective is to get where you're going fast and reliably, the Right-of-Way Class tells you a lot about a services's potential to do that, while the rail-bus distinction, in isolation, tells you nothing. The fact is, both rail and bus technologies are capable of the complete spectrum of possibilities. Both can average 6 mph (10 km/h) in Class C situations, and both can run Class A at 60 mph (100 km/h) or more.

RIght-of-way isn't the only thing that matters for getting you where you're going. There's also stop spacing, with its inevitable tradeoff between speed and local access.

Stop Spacing vs Rail-Bus Distinction

Rapid, Limited

(faster = fewer stops)

Local-stop

(slower = more stops)

Express

(one long nonstop segment)

Rail

“Subway”, “Metro”, some commuter rail.

Tram / Streetcar

Some commuter rail.

Bus

Bus Rapid Transit,
“Rapid Bus”, “limited-stop” bus

Local bus

Commuter express bus (often on freeway)

… and of course there are other essential distinctions like frequency, which are also entirely separable from rail and bus technologies.

UPDATE: Please note, yet again, that contrary to early comments I am NOT claiming that these are the only distinctions that matter. As I laid out in some detail here, there are several distinctions that matter. In fact, one of the reasons that people cling so hard to the rail-bus distinction is that the other crucial distinctions are a little more complicated and require some thought, and it's hard to think about this stuff in the political space where decisions get made.

Rail services do tend to be presented in ways that "package" the various crucial dimensions of usefulness. Typical metro systems, for example, are guaranteed to be frequent, with rapid stop spacing, and Class A right of way, because all three are intrinsic to the metro technology, so there's a psychological "packaging" effect when you see a metro map; you can be confident that this means a certain level of service.

I think these tables are interesting because now and then I meet someone who divides the world rigidly into rail and bus, often aligning these categories with a rigid class distinction (William Lind, say) or simply claiming that rail does beautiful things and buses don't. In that view, the different columns of these tables are secondary and interchangeable, while the rows express something absolute.

Patrick Condon, for example, proposes that instead of building one rapid transit line (Class A, rapid stops) we could just build lots of streetcars (mostly Class C, local stops). That can make sense if you judge technologies entirely on their influence on urban form, and prefer the kind of form that seems to arise from streetcars. But it will be just incoherent to a transit planner who's been trained to help people get places, and wonders if he's being told that nobody cares about that anymore. Because if you do care about personal mobility — people getting where they're going, now, today — you have to care about the columns.

I hope to leave this topic for a while, but I do think it's worth coming back to tables like this to ask yourself: Do I tend to divide the world according to the rows first, or the columns? If so, why? Is my way of slicing this table something I've discovered about the world, or something my mind is imposing on it?

how universal is transit’s geometry?

Posted on March 1, 2011 in Amusing, Basics, Be on the Way, Meditations, Philosophy

Suppose that somewhere else in our universe, there’s another planet with intelligent life. We don’t know what they look like, or what gases they breathe, or what they eat, or whether they’re inches or miles tall. We don’t know whether they move by hopping, drifting, or slithering. We don’t even know if their lived environment is largely two-dimensional, like the surface of the earth, or freely three dimensional, perhaps a cloud-city full of cloud-beings who drift up and down as easily as they drift left or right. We don’t know what they call themselves, so let’s call them borts. Continue Reading →

basics: expertise vs. activism

Posted on February 21, 2011 in Advocacy, Basics, Light Rail, Los Angeles, Meditations, Mobility, Philosophy, Rail Transit, San Francisco, Seattle, Streetcars (Trams), Technophilia, Toronto

The planning professions work in a grey zone between expertise and activism, and managing these competing impulses is one of our hardest tasks.

As a transit planning consultant, I don’t worry much about being perceived as an advocate of transit in general. Experts in any field are expected to believe in its importance. But I do try to keep a little distance between my knowledge about transit and the impulse to say “You should do this.” A good consultant must know how to marry his own knowledge to his client’s values, which may lead him to make different recommendations than he would do as a citizen, expressing his own values. Continue Reading →

tadpoles of new zealand: an auckland transit animation

Posted on February 19, 2011 in Amusing, Auckland, Maps, Meditations

There's a lot of potential for animation of Google Transit data, and we're just starting to see it explored. Some results will be rich with information, differentiating various kinds of service so that you can see how they dance together. Chris McDowall's animation of a day's transit in Auckland is less informative but correspondingly more meditative. Buses, trains and ferries are all rendered as earnest little tadpoles (or comets, or sperm, or viruses, depending on your sense of scale).

(An animated map of Auckland's public transport network from Chris McDowall on Vimeo.)

It nicely illustrates the point that frequency is what makes a route into a line. The line that goes really solid during the peak is the Northern Busway, which is far more frequent than any of Auckland's rail lines.

UPDATE: Commenter "numbat" points out that on the island at the east edge of the image (Waiheke Island) you can see local island buses pulsing with ferries that link the island to Auckland's CBD.

Happy Canadian Thanksgiving

Posted on October 10, 2010 in Meditations, Montréal, Toronto, Vancouver

This post is sentimental and off-topic, apart from its obvious link to the triumphs of Canadian transit and of Vancouver in particular. But hey, it’s my blog.

Though I lived in Canada for only a year, I hope my fondness for the country comes through in this sentimental meditation on Canadian thanksgiving. I wrote it five years ago around this time, when I was based in Vancouver, but it all feels true enough today.

Thanksgiving Day in Canada is Monday, October 11. May it be a day of joy and gratitude for all of HT’s Canadian readers, and for anyone who’s ever admired their remarkable nation.

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