It's one of the better videos I've done, and if you have heard my talks in the past, you'll find this one pretty new.
It's one of the better videos I've done, and if you have heard my talks in the past, you'll find this one pretty new.
A transit planner in a suburban agency asks an eternal question:
Do you have any examples of best practices in transit service in large business parks? I am looking for some creative solution, such as a transit to vanpool connection, or a site redesign for accessibility.
If you have an opportunity, please share some examples, thoughts, etc.…
Note: This popular post is being continuously updated with useful links and comments. Come back and it may be improved!
In the United States, but occasionally in Canada too, voters are sometimes asked to decide whether to raise taxes to fund transit improvements. I'm often asked whether I support these things. I don't like telling people how to vote, but I can point out some predictable patterns in the arguments, and some universal facts about transit that you need to keep in mind.
1. In growing urban areas, transit needs grow faster than tax revenues.
This problem is mathematically inevitable.
As cities grow, and especially as they grow denser, the need for transit generally rises faster than population, at least in the range of densities that is common in North America. This is completely obvious if you think about it, and I stepped through it in more detail in Chapter 10 of Human Transit. In brief: Suppose a particular square mile of the city doubles in population. Transit demand would double because there are twice as many people for whom transit is competing. But independently of that, if density is higher, each person is likely to find transit more useful, because (a) density creates more disincentives to driving and car ownership while (b) density makes it easier for transit agencies to provide abundant and useful service. Those two separate impacts of density on transit, multiplied together, mean that transit demand is rising faster than population. Again, go to my book for a more extended and thorough argument.
However, existing revenue sources are usually growing, on average, no faster than population. The various tax streams that support transit have a range of differences, but they are not going to grow massively faster than the population is growing.
So if the city is growing denser, transit needs are growing faster than transit revenues. This is nobody's fault. It's a mathematical fact about the geometry of transit and density.
If transit and roads were thought about together, you would not see this exponential growth in total transportation spending, because as populations grow denser, they need fewer highway lanes per capita -- precisely because they're using transit, walking, and cycling so much more. But we usually don't think about those things together, unfortunately.
2. As transit demand grows, you sometimes need a major project.
As transit demand grows in a growing city, it hits crisis points where the current infrastructure is no longer adequate to serve the number of people who want to travel. Several major subway projects now in development are the result of transit's overwhelming success using buses. I'm thinking, for example, of Second Avenue in New York, Eglinton in Toronto, Wilshire in Los Angeles, Broadway in Vancouver, and Stockton-Columbus in San Francisco.
Broadway, for example, has local buses running alongside express buses, coming as often as every 3 minutes peak hours, and they are all packed. In that situation, you've done just about everything you can with buses, so the case for a rail project is pretty airtight. In all of the cases I mention, the rail project usually has to be a subway, because once an area is that dense, it is difficult to commandeer enough surface street space, and we tend to have strong aesthetic objections to elevated lines in these contexts.
These big projects require huge lumps of money. So as transit demand grows, its revenue needs don't just grow faster, they grow in a lumpier way, with big chunks of money needed at once.
3. Not all rail projects are about improving transit.
Note, however, that not all rail projects are intended to solve capacity problems and increase the mobility of large numbers of people. Some are designed to stimulate development. (Many do a mixture of both, but the degree of mixture matters because the reasons to support them are so different.) For example, a proposed transit line may connect major destinations, or it may head off into an area where few people live now, solely to trigger development that will put more people there in the future.
Stimulating urban development can be a very good thing, but when you see those arguments you may want to ask these things:
Again, these questions apply only to a big project whose evident purpose is predominantly to stimulate development, rather than to serve the city as it is.
4. Who is for and against? (But don't overreact!)
Everyone looks at this, and it's a big source of hysteria.
All tax measures will have opposition from the political right. In most US contexts, for example, you can write off anywhere from 25% to 40% of the vote if you are proposing taxes for anything at all.
You will also hear lots of dark tales about the supporters. Your proposed measure is probably supported by engineering firms, urban real estate interests, transit labor unions, and anyone else who's going to be personally enriched if the measure passes. This is normal and boring and should not affect your vote. Never vote no on a measure just because people are supporting it for partly selfish reasons. Those motives are in play in any campaign for anything.
Likewise, you should never vote one way or another because of how you feel about the campaign. Campaigns are thrown together quickly, work under immense time pressure, and usually make mistakes. The campaign will be over soon, but the effects of your vote will last much longer.
But here is one thing to watch for. You should be alarmed if there is a significant argument against the measure coming from people who usually support transit taxes. Opposition by environmentalist or progressive transportation policy groups should be a yellow flag. Unlike the political right, these people really want measures they can vote yes on, so if they're voting no there is probably something wrong.
I don't mean, of course, to give every self-proclaimed transit advocate a veto. As in any business, some of them are crackpots. But this opposition should be concerning. Notice it if it exists, or if it doesn't.
5. But the transit agency looks so wasteful ...
This is a tough one, because I can't promise it isn't true.
But be suspicious of what the anti-tax folks point out. Many things that look like waste make sense in another light. Your transit agency may also have tried something that didn't work out well -- they make mistakes, like anyone. They've probably spent money on things that are easy to ridicule from certain quarters, like public art or maybe driver restrooms that someone thinks are too grand, though often these are the result of complex agreements that help get a transit project built.
6. But the managers have such big salaries!
You'd better hope they do. These are complex jobs with appalling responsibilities. Many of the people in them could go to the private sector and make ten times as much. The best of them are in this business because they believe in it.
People expect transit executives to do impossible things every day -- like run buses on time in wildly variable congestion, or cut labor costs without setting off rebellion in the workforce, or run service wherever anyone feels entitled to it no matter what the cost. The political pressures on them are off the charts. Not every transit executive deserves that compensation, but in those cases the problem is usually the executive, not the compensation.
In any case, executive compensation is trivial in the context of transit agency budgets. It's the compensation and management of the whole labor force, especially bus and train drivers and mechanics, that determines how efficient the agency is, and how much service you'll have. I am not defending every executive perk or unnecessary management position; I've seen plenty of waste in my career. But cutting executive wages will not unlock much money for better service.
My own view is that transit executives -- indeed, all transit staffs -- should be paid very well and should face very high expectations, especially for clarity about what the real issues are. You have a right to clear and transparent communication from your transit agency that helps everyone understand the choices are facing your community, how they're being addressed, and what to do if you disagree.
Maybe your transit agency isn't like that. Maybe you're really mad at them.
Well, if you don't like the management of your water department, does that mean you don't need water?
Voting no on urgently needed things is a poor way to protest waste and inefficiency in government. Instead, get involved in fighting those issues. Send your elected officials a letter saying "Don't you dare read my vote for this as support for that!" Find other ways to keep up pressure if you think it's warranted. These communications always have more impact than most voters realize.
7. Will transit reduce congestion?
Advocates of car-dependence often object that transit doesn't reduce car congestion, and that car congestion is higher in transit-rich cities. To respond, see here. To understand the exclusionary attitudes behind the transit-doesn't-fix-congestion argument, see here.
8. If you're still confused, vote yes.
Why? Because most people do the opposite. They vote no if they don't understand, which is why it's hard to get anything done. If you vote yes, you're no more likely to be wrong than the no-voter is, and in a world where government often can't seem to do anything, you're voting for doing something. That sends an important signal in itself.
As a transit advocate, I've voted no on a couple of transit measures in my time, always with great regret as well as frustration. But usually, even if the plan contained something I object to, I've voted yes. Even a project that achieves its outcomes inefficiently usually achieves something. Even a project that's solely designed to trigger condos for the very rich will at least get more rich people into the inner city, where they will then start caring about transit and supporting the kinds of transit a rich and vibrant city really needs. And while the failure of a ballot measure may be because of public objections to how the money was to be spent, lazy journalists and elected officials often treats it as a no to transit itself, so it often takes years to get another measure going.
So if you're still confused, it comes down to this:
All the other confused people are voting no. So vote yes.
I talk a lot about altitude in planning and network design. But sometimes my airplane metaphor gets mangled a bit in translation, as in this otherwise fine article about our work in the Raleigh, NC area.
So wherever you encounter it, here is what I mean:
If you are higher up from the surface of the earth, you can see a larger area, but in less detail. At lower altitude, you see a smaller area, but in greater detail.
Likewise, there are high-altitude planning projects, which look at a large area (a city, a county, an urban region) and identify appropriate solutions to problems that exist at that scale. There are also lower altitude projects, all the way down to parcel-level development approval, or, in my business, detailed designs of a transit station or a bus schedule.
One of the basic skills you should expect from a planning professional is the ability to control altitude. As in a plane, you need to get up high to see the big picture. If you don't, you'll make decisions that produce bad consequences outside the small frame of the low-altitude problem you were focused on. For example, if land use planning is nothing but development approval, then stuff will get built, project by project, without any attention to the aggregate consequences of that development -- on traffic, on livability, on natural resources, etc.
On the other hand, plans that remain at high altitude -- regional structure plans, vision plans, "strategic" plans, etc -- don't have any effect on reality unless they're implemented by actions at lower altitudes.
So the airplane metaphor works like this: To see clearly, we need to get our plane to a high altitude. But to implement anything, we then need to land the plane.
The key is to lose altitude in a controlled and intentional way. You look at the problem at high altitude and see the solutions that make sense at that level. Maybe, for example, you identify a corridor that should have some kind of rapid transit but you don't specify what the technology should be, or even an exact alignment. Then, later, a study focuses just on that corridor and explores all the options for it. All the remaining steps from there to implementation are part of a controlled loss of altitude until finally, on opening day, you're on the ground: The thing you planned is actually happening.
However, there is always the danger of uncontrolled loss of altitude, i.e. crashing the plane. This happens when a conversation at a certain altitude is interrupted or shut down by a low-altitude issue. For example, when we're exploring the possible structure of a citywide network in a city, an operations manager may interject that a particular turn isn't possible, or that this business would never let us put a bus stop there. Those comments are plane-crashers. If we succeed, at high altitude, in developing a network vision that excites people so that they want it to succeed, all those problems will be easy to solve. But if we let those little concerns veto the high-level thinking, we'll never be able to talk about the big picture.
This comes up often among people who have strong emotions about particular transit technologies. They fervently support or oppose some technology option, so want to know the answer to the technology question before we have properly thought through higher altitude questions: What are our goals for transit? How do we balance predictably competing goals? What kind of citywide network do we want? What kind of mobility and access do we want to provide?
If those sound like hopelessly abstract questions, read the introduction to my book. There, I explain how we can approach these questions so that citizens can answer them with an awareness of the consequences. That, in turn, means that the decisions they make can be implemented. The plane can descend, and finally land. The key, as I explain there, is to listen to your plumber!
Photo: Airplane Contrails- Creative Commons: Ian Renton, 2011
There is a lot of confusion out there about Park-and-Ride. Is it necessary for ridership? Are motorists entitled to it? Can it last forever?
Let's start with the basic math.
It's a contradiction.
When a transit agency provides free or underpriced parking at a station where the land value signals that there is a higher use, it is subsidizing motorists in two ways. First, it is forcing a low-value land use to prevail over a high value land use, and second it is making a much bigger investment in access by motorists than it makes in access by people who get to the station in other ways. I am using the word subsidy in exactly the same sense that any other artificial limit on price is a subsidy.
Obviously the problem is much worse where the rapid transit is of the highest utility and quality and where the ambient land value is therefore higher. This is why free Park-and-Ride is much harder to justify on high-frequency metro systems than on infrequent outer-suburban commuter rail in most metro areas.
Low-cost Park-and-Ride can make great sense where a station area is undevelopable (floodplains etc). There's also an important role for distributed, small-scale Park-and-Ride created by sharing existing spaces. Transit agencies often make deals to share parking with land uses that peak on weekends and evenings, such as houses of worship and entertainment venues. These are great ways of providing some car access at very little cost to the public.
But the law of supply and demand generates some facts about free Park-and-Ride that many people don't want to hear, but that we really can't protect them from:
It's easy to feel entitled to a free Park-and-Ride space. But nobody can repeal the law of supply and demand, and that's what we're dealing with here.
Photo: Park and Ride at Auckland's Constellation Station, Auckland Transport
Are your transit authority and city government working together to make buses as functional and useful as possible? A new TRB report summarizes the industry's own consensus on where the easy wins are for improving bus service. Peyton Chung has the rundown:
A recent report on “Commonsense Approaches for Improving Transit Bus Speeds“ surveyed not just the scale of the problem, but also solutions. In it, 59 transit agencies across America shared how they have responded to the scheduling problems presented by ever-slower bus routes. The agencies report on the most successful actions they’ve taken to improve bus speeds and reliability. Here they are, listed in descending order of popularity.
- Consolidate stops: More than half of agencies have thinned bus stops, some by focusing on pilot corridors, and others by gradually phasing in policy changes. Many agencies moved stops to far side of intersections at stoplights, and 13 agencies adopted physical changes like longer bus stops or bulb-outs, which help passengers board faster and more conveniently.
- Streamline routes: Straightening out routes, trimming deviations, eliminating duplication, and shortening routes didn’t just simplify service, it also sped up service for two-thirds of the agencies that tried this approach.
- Transit signal priority: The 22 agencies with signal priority can change stoplights for approaching buses. They mostly report a minor to moderate increase in bus speeds as a result. In fact, agencies singled out traffic engineering approaches like TSP as the closest to a “silver bullet,” one-step solution.
- Fare policy: Several agencies changed fare structures or payment methods. The one agency that collects fares before passengers board, and lets them board at both bus doors, decreased bus running times by 9 percent.
- Bus Rapid Transit: Ten agencies combined multiple approaches on specific routes and launched BRT service. Of those that measured the impact, almost all reported a significant increase in speed, typically around 10 to 15 percent.
- Vehicle changes: More than half of agencies have moved to low-floor buses, which reduce loading times by one second per passenger. Smaller buses might be more maneuverable in traffic, and ramps can speed loading for wheelchairs and bicycles.
- Limited stop service: Although new limited-stop services offered only minor to moderately faster speeds, it’s a simple step and 18 agencies reported launching new limited routes.
- Bus lanes: Dedicated lanes are used by 13 agencies, and one reported that “most routes are on a bus lane somewhere.” When implemented on wide arterial streets, this moderately improves speeds.
- Adjust schedules: Almost all of the surveyed agencies have adjusted running time, recovery times (the time spent turning the bus), or moved to more flexible ”headway schedules.” All of these actions improve on-time performance reliability for customers, and reduce the need for buses to sit if they’re running early.
- Signal timing: Synchronized stoplights along transit routes can make sure that buses face more green lights than red, but only have a mild impact on operating speeds.
- Express service on freeways: This strategy had the largest impact on speeding up buses for the three agencies that tried it.
Many transit agencies have adopted at least some of these changes. For example, Streetsblog has covered San Francisco Muni’s efforts to consolidate stops, launch limited-stop service, rebuild stops, install signal priority, and use prepaid fares to allow passengers to board at both doors.
The survey also asked about the major constraints that agencies faced when attempting to improve bus speeds. More than a third of them cited a lack of funding and competing priorities within the agency — streamlining a route, for instance, may reduce the area covered by the service. More than one in seven agencies cited a lack of support from other government agencies, like transportation departments in charge of streets and signals (in San Francisco, Muni benefits from being housed within the city’s transportation department). Rider opposition, particularly to removing bus stops, and existing traffic congestion, also thwarted some attempts to streamline bus operations. Interestingly, few agencies cited community opposition or a lack of staff time as constraints.
That last paragraph is crucial. Buses don't improve because the people who want them to aren't sufficiently organized and focused to balance out the kinds of resistance that the report lists. Most local elected officials who are responsible for transit get great earfuls from those defending every detail of the status quo, while advocates for improvement can sound vague and abstract by comparison.
(And by the way, our firm specializes in helping transit agencies work through all of these issues, including their political dimension!)
In my book Human Transit, I argued that the underlying geometry of transit requires communities to make a series of choices, each of which is a tradeoff between two things that are popular. I argued that these hard choices are appropriate assignments for elected boards, because there is no technical ground for making one choice or the other. What you choose should depend on what your community wants transit to do. Examples of these choices include the following:
Note that while the framing of these choices tends to make them sound binary ("Ridership or coverage?") the choice is not between two boxes; it's of a position on the spectrum where the two terms define the extremes. You don't have to choose between ridership or coverage, for example, but you have to choose a point on the spectrum between them, and you have to accept the mathematical fact that, as on any spectrum, moving toward one extreme implies moving away from the other.
In the Epilogue of HT I briefly introduced the idea that for each of these choices, one option seems to trigger a positive-feedback loop, while the other option does not. Here is a new and expanded diagram of that idea. The image below is fuzzy, so download here: Download Abundant access diagram streamlined '15-05-08 (Tip: Print it on A3 or 11x17. There's a lot here.)
What do I mean by positive feedback loop? On each of these choices, the option that points toward the center leads to a particular kind of network that supports all of the goals implied by all the centerward choices. For example, if you plan your network for maximum ridership rather than coverage, you also generate a network that encourages higher walking distances, that supports easy connections rather than complexity, and that tends to present the strongest case for facilities that protect transit from congestion.
On the other hand, the options that point outward from the center tend not to support each other. You can achieve the goal implied by these outer choices, but (arguably with some exceptions) each one will require a separate effort. For example, if you believe walking distances to transit should be low, as seniors tend to advocate, then you need to put parallel transit routes -- and the stops on those routes -- very close together. This does nothing to advance any of the outer "outward" goals, whether it be growing peak demand, or avoiding connections, or achieving a luxurious experience that will compete with a BMW.
Another way of saying this is that the choices that point inward all point to a single set of network design principles, and a single set of consistent priorities, while the choices pointing outward lead to many different kinds of network design and competing priorities.
What happens when you move toward the center? These choices converge on a single, consistent goal that I propose to call Abundant access, which means:
The greatest possible number of jobs and other destinations are located within 30 minutes one way travel time of the greatest possible number of residents.
[Why 30 minutes? The question is tangential to my point, and other figures could be used, but if one has to pick a figure the most solid basis is Marchetti's constant [PDF], the idea that humans throughout history have tolerated about one hour of daily travel time. Obviously, shorter or longer periods may apply to trips other than the commute.]
For any individual, abundance of access can be visualized using a map of isochrones, like this one by Conveyal for downtown Portland, which shows the area you can get to within a fixed amount of time on some combination of transit and walking.
(In these maps, blue is a 15 minutes travel time, green is 30 minutes, and pink is 45 minutes. Unlike some imitators, these calculations include waiting time and therefore accurately convey the impact of frequency.)
Of course, any quantification of abundant access must consider not the area but the amount of stuff in it: jobs, retail, recreational opportunities, hospitals, all the things that form the universe of destinations. As a matter of public policy, it must also maximize over the largest possible share of the population. In the case of transit, the population over which abundant access is most cost-effectively maximized tends to be a more urban, high-density population, because among readily available measures, density is one that best predicts the intensity of ridership that will arise from a service investment. (Fortunately, that's fairer to than it sounds, because people living at high densities use much less road infrastructure per capita than people living at lower densities.)
The goal of abundant access has several kinds of appeal.
First, it can be measured objectively without recourse to psychology or culture. Ridership estimates are based heavily on travel times that approximate the notion of abundant access, but they also add psychological factors that are less stable, such as observed preferences for particular technologies. These factors may be emotionally vivid, but like many emotional factors they are likely to change with time and especially with generations -- just as emotional attitudes toward cars are changing now. Abundance access measures a fact that is entirely objective -- travel times. Unlike emotional reactions to technologies, the value of access has been constant across millennia of human experience.
Second, abundance of access is literally a quantification of freedom, in the sense that matters to us in transportation. Isochrone maps like Mapnificent's, in particular, show us our freedom in a very immediate way: here is where you are free to go, now. Abundant access measures the transportation element of opportunity of all kinds, which is one of the main reasons people have moved to cities since their invention.
The concept of freedom is sadly undervalued in much urbanist discourse, and I am always looking for ways to reintroduce it. Much urbanist writing, for example, is blatantly prescriptive ("you should want this kind of community"), which feeds conservative stereotypes of urbanism as manipulative or coercive. We need to be able to talk not just about ideal communities but about freedom and personal responsibility, a frame in which all the great urbanist ideas -- and all the urgent environmental imperatives -- can be stated equally well. In that frame, the key idea is not "the good" but "choice," where freedom of choices also implies responsiblity for your choices.
So again, all of this work is descriptive, not prescriptive. I'm not saying that you should like the goal of abundant access; that would be value judgment, and you get to make those for yourself.
I am saying, though, that abundant access as an idea has certain features and consequences, including a tendency to be self-reinforcing. As mapped along the various axes of choice, abundant access is a single consistent vision whereas the opposite choices lead to many unrelated visions.
Still, you don't have to like it. My role, as always, is to describe consequences clearly, and help people choose.
[Updated 8 May 2015 with streamlined diagram.]
Greater Vancouver's transit agency TransLink has now published something called the Managing the Network Primer [Download PDF] and has a new webpage devoted to this and similar themes. It's a simple explanation of why effective transit networks are designed a certain way. It pushes back on the confused and confusing notion that "buses are flexible compared to rail," by emphasising the ways that all kinds of transit work or fail along the same geometric principles. It can also be used to explain to a reasonable person why the bus can't just deviate to serve (or avoid) her house, business, or development project. I'm honored to have made substantial contributions to it, in the context of my ongoing work with TransLink.
Subliminally present in this document -- and more explicit, I hope, in the next version -- is that this is also a primer for transit-oriented land use planning. If you want good transit at your home or development or senior center or business park, you need to locate it where transit can be efficient, and therefore abundant. So by understanding what efficient transit looks like, you can get a better grasp of what truly transit-oriented development looks like.
So like my book, and like my course, this document will be interesting for transit geeks but is really meant for people in land use planning, development, architecture, and other related fields. These are the people who are deciding how effective transit can be in the future -- every bit as much as transit planners are.
Once again, TransLink is being careful not to tell any city what it should do with its land use. Rather, this is part of a process of explaining the transit consequences of the choices a city might make.
If your regional transit agency is giving its city governments the impression that it's telling them what to do, it may have something to learn from documents like this. Getting this message right is something I've worked on for a while, and it was the subject of my recent keynote at the Canadian Urban Transit Association annual conference. Let me know if I can help.
See new updates at the end, based on comments to May 4.
Ricky Leong in the Calgary Sun on why Calgary should spend more money serving far-flung suburbs:
Here’s the thing about providing transit to our far-flung suburban neighbourhoods. The benefits of new transit services will be felt by people everywhere in the city, not just those residents who choose to take the bus and train.
Fewer cars on the road should lead to better driving and cycling conditions for everyone, everywhere, for example.
Suburbanites choosing transit over private vehicles should also mean less wear and tear on roads, so the savings from reduced maintenance would be a net benefit to the entire city.
I'm not trying to embarrass Leung, because the error here is extremely common in journalism, as it is in public perceptions. Last November Lisa Margonelli built a long New York Times article around the same mistake.
Buses circulating in low density suburban areas (as opposed to express to Park-and-Rides) can serve many valid purposes, but getting cars off the road generally is not one of them.
The universal fact that these people are missing is that buses circulating in low-density areas -- especially where street networks require transit to thread slow and complex labyrinths -- is a predictably low-ridership service. Outside of a bit of rush-hour activity and sometimes a surge at school bell times, this is the fact of life about local service in low-density suburbs. If you don't believe me, ask for your own transit agency's stop-level ridership data and compare it to the density and walkability of the area around each stop. Apart from anomalies created by special land uses, you will find it is much higher in more urban parts of your community where these conditions are more favorable.
In 20 years of looking at detailed transit data, I've never seen a local suburban bus route whose performance (ridership per unit of service cost) was anywhere near that of a frequent urban bus route operating in area whose layout is favorable to transit.
("Favorable to transit" means (a) higher density, (b) gridded local streets that provide easy direct access to stops for pedestrians, (c) a safe and pleasant pedestrian environment, (d) a mix of land uses and (e) simple linear paths, usually arterials, where transit can operate efficiently and effectively. These features tend to be found in older inner cities, but they can be replicated and in some cases even retrofitted.)
Indeed, because transit's market is mostly the area within walking distance of a stop, low density and obstructed street patterns are the very definition of a poor transit market that will yield much lower ridership on investment, and that therefore justifies a poor level of service. Poor ridership out of low density isn't an empirical fact; it comes close to being a mathematical fact, because in most cases density around a stop is the size of that stop's market.
To claim that this predictably low-ridership service will result in "fewer cars on the road" is thus a geometrically incoherent claim. "Fewer cars on the road" is the result of people riding transit, not transit existing. So a service that is guaranteed to generate few riders per unit of cost will is guaranteed to get fewer cars off the road per unit of cost, compared to one that is guaranteed to generate many ridership per unit of cost -- such as a line in transit-favorable geography or a rapid transit corridor.
The only high-ridership form of public transit that can serve low-density suburbs with obstructive street patterns is based on Park-and-Ride. Where land values permit, abundant park-and-ride and fast radial services can get cars off the road efficiently. Radial rapid transit (bus or rail) is also good because new transit-favorable neighborhoods can often be built later around its stations. Park-and-Ride needs to be understood broadly as also accommodating dropoffs, Bike-and-Ride, etc. But the key thing it does not require is for a bus to actually drive around inside a labyrinth of suburban local streets.
If a transit agency's objective is to get cars off the road, then like any business you start by focusing on your competition's weaknesses. The car is least convenient in areas of high density and good walkability, and geometrically these also provide the the highest ridership per unit of investment. The one other area is the suburban commute corridor -- the freeway into the city -- where congestion during peak periods makes the car a weak competitor. That's why peak commute services -- to Park-and-Ride, not to people's front doors -- is also a high-ridership prospect, and one that gets cars off the road efficiently.
Again, there's nothing wrong with running bus routes around in low-density suburbs. But it is a low-ridership proposition and therefore can't be justified by many sustainability outcomes; it's justification has to lie in social needs and perceptions of equity among neighborhoods. If your city really wants to get cars off the road, however, it's not a good way to serve that purpose.
This kind of confusion is why elected officials should be asked to think more clearly about how they want to balance the conflict between ridership-related goals (including lower subsidy, fewer cars on the road, and resulting sustainability outcomes) or coverage-related goals (including lifeline access and "equity" across all arts of a community. Both goals are noble, but don't pretend to be doing one if you're really doing the other.
Better still, ask elected boards to adopt policies about how much of the budget should be spent pursuing ridership -- which means running services where high ridership is the predictable outcome -- and how much should be spent pursuing coverage, i.e. distributing service everywhere regardless of low ridership. The Reno area's transit board did this in 2005, as the result of work I did with them, and as a result, this whole conversation is much clearer, less personal, and more clearly tied to the community's actual values.
For a more detailed exploration of this fundamental issue, see Chapter 10 of Human Transit.
UPDATES: Comments on this one are often critical, but what I see in them is that:
This isn't an easy topic. Many of the terms are emotive. But there's an important fact here. Again, see Chapters 9 and 10 of Human Transit for much more thorough discussion.
When people think of a new transit need, they often jump prematurely to the idea that they need a new route. This new article of mine -- linked to in Chapter 7 of my book -- explains why this can be a bad idea.
At several points in the book, I include links to articles on the blog that expand more fully on a topic. The article on operating cost is now online, here. Remember: If you don't understand operating cost, you don't understand transit!
How do transit network designers go about their task? Surprisingly little has been written about this. You can pick up books that appear to cover the "network planning" process and find examples of good and bad networks but rarely a description of how to do the design thinking itself. EMBARQ's recent manual for network planners in India, for example, provides great detail about how to analyze demand and evaluate results, but show no awareness of the really challenging task of network design, which sits in between those tasks.
I'm thinking my next book will probably be a little e-book talking through the process in more minute detail. For now, let me talk through a quick example, just to capture the outlines of how a network designer might approach a problem.
My example is the core of Halifax, Nova Scotia, a dense peninsula built out mostly before 1945 and therefore highly conducive to transit. It isn't the only transit-conducive place in the metro region, but it's the largest, and its peninsular location helps us isolate it as a design problem, so I can discuss it in a brief example.
The peninsula's developed area is about 6 km (4 mi) long and 3 km (2 mi) wide at its widest point.
First, we take stock of the strategic focal points, especially major destinations and chokepoints.
Major destinations are part of why you'd focus on the Halifax peninsula as the core of any effective regional transit strategy. The strongest transit destinations are:
Those are usually places with lots of people coming and going, not just employees. What kinds of places are those? Large scale:
They're all on the peninsula. Provincial government, two universities, the major medical centers serving all of Atlantic Canada, and retail centers both downtown and on the west edge.
The other reason you focus on the peninsular core is that it's already dense and walkable, because most of it was built before 1945. So much of Halifax is here, and is so amenable to transit, that a strategy trying to optimize transit mobility must take full advantage of these opportunities. If you care about mobility to an outer suburban community, you must care about circulation within the peninsula, because many of your citizens are going there and they may need to move about within the peninsula while there. What's more, peninsula residents who choose not to own cars (which for many could be a viable and liberating choice) will sometimes need to travel outward, and a transit-intensive peninsula will generate outward transit demand further supporting the radial services that outer suburbs need.
So what do we have on the peninsula?
All access is via just six chokepoints (red circles), plus ferry lines east across the harbor. These will be ideal locations for transit connection points (yellow rectangle with T) because many lines, offering travel to many origins and destinations, must converge there anyway. So the transit agency has done a good job here. Except for the northernmost bridge and the northernmost exit to the west, all the chokepoints have transit connection facilities nearby.
The whole peninsula is dense and there are tall buildings here and there throughout, but the big concentrations are in the areas I've shaded. Downtown is the blue area on the waterfront, while the parallel blue box further west is the medical zone. The magenta zones are the major universities. The southern one, St. Marys, is a Catholic school with about 7000 students. The northern one, Dalhousie, is a major public university (16,000 students) that spills eastward along the green axis toward downtown, mixing with major medical facilities, office buildings, and dense, often student-oriented housing. This green area is the core of a potential sustainable-transport paradise, because all the elements that make Halifax in general such a strong market (listed above) are mixed especially closely here, while the dominance of the universities, medical facilities, and shopping guarantees all-day two-way flow, the best situation for highly efficient transit.
I hope you've followed all this even if you don't know Halifax, because the same kind of assessment needs to be made of any city. This doesn't mean that you have to have all of Halifax's features, but you need to be looking for those features you do have, with particular focus on density patterns and chokepoints, becuase these are the best starting point in defining a strategic outline of the network, within which you can then develop local ideas in more detail.
Now we look at the network of major transit-operable streets:
The grid pattern means that some kind of high-frequency grid is almost certainly in order, so that people can get anywhere to anywhere on the peninsula with at most one connection. Obviously, since all trips within the peninsula are short, connections are a bigger disincentive, so we'll try also to link major destinations with direct services. However, if we made direct service everywhere to everywhere our primary goal, we'd end up with lots of overlapping lines and would struggle to afford enough frequency on them all.
Notice, however, the way the southwest edge of the peninsula runs on a diagonal compared to the street grid. That's an invitation to draw L-shaped lines, an east-west grid element connected to a north-south grid element. Like this:
Grid lines that "bounce" off of diagonal edges, like this one, tie together more destinations without a connection while remaining complete grid lines (i.e. running all the way across the grid) so as to maximize the number of other connections that can be made.
But Oxford Street sort of peters out at the north end, so where do we go? We "tie off" or "anchor" the line by going to a nearby major destination where many other connections will be available. Fortunately, one is nearby. The "T" just southwest of where Oxford ends is also a major shopping center.
Meanwhile, at the other end, we notice that many connections throughout the east-of-harbour Dartmouth area are available at a "T" just over the bridge. A single frequent line to that point, covering many of the major destinations of the peninsula, can plug into all of those connections, so that the whole catchment area has easy one-transfer access to most of these destinations. So we have this:
And in fact, Halifax's Metro Transit has already had the same thought. Their most frequent transit line, Line 1, looks like this:
It's on Spring Garden instead of South, but that's only about 400m difference. The university and most medical facilities in the area are adequately served from either. But Spring Garden is more of a continuous "mainstreet" through this area, although major institutions front on both.
So what have we missed? Well, the next big corridor is Robie, which (along with nearby parallel streets like South Park) is really the medical axis. It would have been tempting to turn our first line north along Robie instead of Oxford, because while Oxford is perfectly fine lowrise density Robie has the highrise intensity of institutions. At the south end, Robie bounces off the diagonal grid-edge as Inglis, which gets us to the smaller university, St. Mary's. If we bounce again at the east end of Inglis we head north along Barrington into downtown. Once we're past Spring Garden we're duplicating the first line, but we're virtually downtown by this point, so duplicative service on one street, adding up to very high frequencies, makes sense and can be useful for internal downtown demand. (Remember, the shorter the trip, the higher the frequency you need to compete for it.) So that suggests something like this:
This is not what existing service does. Robie now has an overlay of several lines doing slightly different things, several of which end in a very odd one-way loop at the south end, like this one, rather than going downtown.
Perhaps it's just trying to turn around. One-way loops are a good idea at outer low-density ends of lines, but they introduce needless confusion and circuitousness in dense areas, where it should be possible to serve all markets two way.
Meanwhile, back in our ideal grid, our Robie-Inglis route encountes a perplexity at its northwest corner. At Chebucto Road, Robie seems to branch into the continuation of Robie and the larger Windsor Road, which takes on a more car-oriented character as it heads for the chokepoint at the far northwest corner of the peninsula, near Clayton Park.
This situation is tricky, and I wouldn't make a recommendation at the high-level scale of this exercise; much deeper knowledge of existing travel patterns and land uses would be needed. For now, let's assume that the smart thing to do is follow Windsor, because it completes the grid, serves a chokepoint, and thus is useful both as an internal corridor on the peninsula and a gateway path to the larger region.
Now, you can see how some east-west frequent lines would largely complete the grid. To work best they'd have to aim for the chokepoints too, so that while offering intense local circulation within the city they'd also provide access to much of the peninsula from the surrounding suburbs. Metro Transit has already drawn most of these lines, and they seem to work pretty well except that many aren't frequent enough to really function in a high-frequency grid, or even to compete for the very short east-west trips that they would serve within the dense peninsula.
The dark blue line, existing lines 2 and 4 combined, is already every 15 minutes, but the other two key grid lines here, orange Line 6 on Quinpool and and green Line 9 via the far north, are still every 30, not enough to really function as elements of a grid. Notice too how 6 and 9 bounce off edges of the grid, completing linear corridors before turning to find a major destination and connection point at which to terminate. (Lines always want to terminate at big destinations, called anchors in the business, because otherwise they tend to empty out near the end, leaving permanent wasted capacity.)
Yes, there are still gaps, but we've hit all the major denstinations and most of the peninsula's density. As we turn to those gaps, network design starts to get fun and subtle, as we have to dig into more detailed data to find the clues for how we should patch routes together. And here I'll stop, as I've reached the end of what I can do in such a "high level" view.
But here's my point: I'm almost certain that the lines drawn here, or something very, very like them, would be part of a successful network for Halifax, because they are big-picture responses to issues that are obvious at this big-picture scale. Network designers sometimes fail to take this high-level sketch planning step, and instead wade too quickly into the million possibly interesting details. If you focus on too much detailed data too soon, though, you end up wandering around inside the data, unable to get any big picture "structure" that you can hang onto while you consider the subtler questions.
Also, while it's very important for many people to be able to follow this kind of thinking, designing optimized networks, especially in difficult geography, is a bit of an art. Like any inductive thought, it involves deeply understanding the data but then being open to ideas that come in unpredictable bursts of inspiration, much the way scientific theories come about. The "having ideas" part isn't in many manuals because it's not really teachable; it's to some extent an innate talent.
Consultants like me can help with the subtler thinking of network design, and of course many professional transit planners are adept at it. But you don't have to have those skills, or want them, you can be a more effective advocate if you understand the kind of thinking I've been demonstrating here. If you want to influence transit in your city, you have to understand the basics of the network design problem, as it arises from facts of geometry, facts of transit, and the unique geography of each city. That way, even if you're not ready to do network design yourself, you can assess whether the designers of your own network have done a competent job, and make suggestions that they could actually use.
The British/Australian term "dead running" means "running out of service, unavailable for passengers." I like the term because it could be the title of a zombie movie. I look forward to seeing if it attracts hits.
The North American term is "deadheading," which may remind you of rock fans of a certain era. In both cases, the word "dead" is apt. It's a waste, a loss. It's unavoidable up to the point, but transit agencies are always trying to turn dead time into live, useful time.
The Brisbane Times has a piece by Marissa Calligeros announcing that '28 per cent of bus services are "dead running", where passengers are unable to board.' That's a confusing way of putting it. The reporter must mean that Brisbane buses are dead running 28% of the time.
That sounds like a lot, but "dead running" is the result of two different issues that need to be kept separate.
There's no way to understand Brisbane's "dead running" issue, or that of any other city, without separating these two causes. The Brisbane Times article talks only about the first, but the Brisbane bus system has a massive one-way peak due to its single dominant downtown and relatively lack of direct rail paths for much of the city. Can dead running be better addressed by a rigorous review of whether these one-way peak services can be combined, replaced by links to rail, or otherwise made more efficient? GIven the higher cost of dead running for one-way peaked service, could some of it be converted into two-way, all-day service at less expense than it would first appear?
That's an important question for any city. Details of driver costs vary, but in general, dead running is one of the main reasons that one-way express service (bus or rail) can be more expensive than it looks.
If you want to do things with transit, you need to understand some basics about its geometry and costs, facts that may raise interesting questions about your own goals.
To make this blog more useful as a reference, I've assembled the most important posts on these topics in the far right column under "Stuff You Need to Know."
If you haven't read them all, have at it!
Let me know if you think any should be deleted or others that should be included. The intent is not a list of the "best" posts, but of posts that best lay out fundamentals of network design.
Also, note the new travel schedule under my photo. I'll be in Madison for the Congress for the New Urbanism conference, and in Wellington (NZ) and Halifax (Canada) for project work.
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.
Yesterday I received an email asking about how walking distance standards vary around the world. I don't know the whole world, but in the countries I've worked in (US, Canada, Australia, New Zealand) the view is pretty consistent:
Finally, it's remarkably hard to sift data into a form that produces unequivocal guidance on the question. For example, the leading US guide on transit planning, the Transit Capacity and Quality of Service Manual, offers only this:
(Source: TCQSM Chapter 3, Appendix A, p. 3-93. Discussion and version in US units is on p. 3-9.)
This survey-based graph shows the breakdown of local bus passengers by the distance they walked to get to the service. As you'd expect, few people walk more than 200m in downtown Washington, DC because in such a densely served area, few people would need to. In low-density Calgary, at the opposite extreme, many people have to walk fairly long distances.
But extrapolating opinions from behavior is a tricky business. It's hard to reason from how far people walk to how far they're willing to walk. To do that, you'd have to determine whether each rider would be willing to walk further than he actually has to walk. You'd also have to speculate about each rider's available options. If 1/10 of Calgary's bus riders walk 600m or more, does that mean they're willing to? Or does it mean that these people are so lacking in good alternatives that they feel forced to walk that far? (The difference between "high income" and "low income" Washington DC suggests that range of options does have something to do with it.) Sociologists and demographers can have a field day parsing this question, but they're unlikely to come up with an answer of such statistical certainty that it definitively sweeps the question aside.
So we approximate. We generally assume that 400m is a rough upper bound for slow local-stop service, and that for rapid-transit (usually rail) we can expect people to walk up to 1000m or so.
But when we try to apply these rules of thumb, we hit another hard issue (or at least we do if we're willing to acknowledge it). Are we talking about true walking distance, or just air distance? Over and over, in transit studies, you'll see circles around bus stops being used to indicate the potential market area, as though everyone within 400m air distance is within 400m walk distance.
Remember this graphic?
In both images, the red dot is a transit stop and the red circle is an air-distance radius. If you draw 400m circles around stops based on the assumption of a 400m walking distance, you're implying that the whole circle is within walking distance. In fact, even with the near-perfect pedestrian grid in the right-hand image, the area within 400m walk (outline in blue) is only 64% of the red air-distance circle. With an obstructed suburban network like the left-hand image, it can be less than 30%.
Obviously, the market area around each stop should really be defined by the walkable area, which requires a knowledge of the local pedestrian network. That requires a complete GIS database of every walkable link in the community -- an extremely detailed task that few jurisdictions have been willing to attempt until recently. Even in Canberra, Australia, which is known in the business for the extreme richness of off-street pedestrian connections, no reliable database of them was available for modelling purposes as recently as last year.
Still, if you don't have such a database, it should be easy to adjust the walking distance standard to reflect the problem. If you know you have a good street grid, then you can just adjust the radius to reflect the area within 400m walk. In the right-hand image above, do the math and you'll figure out that if the radius of the red circle is 400m, then a circle whose area is the same as that of the blue diamond -- the actual area in walking distance -- would have a radius of 319m. So if you want to roughly model the actual radius that arises from a 400m walking distance, and you have a well-connected street grid, draw a circle 319m in radius. That doesn't give you the correct boundaries of the area -- it's a circle rather than a square -- but it's a far better approximation than just drawing a 400m circle. I have never actually seen this done, and I'm not sure why.
One reason might be that secretly, we transit planners all want people to walk further. After all, most transit planners don't want to just passively respond to current behavior. If they did, they'd all be highway engineers. Most transit planners believe in the importance of shifting behavior in more sustainable directions, and see both transit ridership and walking as deserving encouragement through intervention. They are also aware of the public health benefits of walking.
But we have a more vivid motive to encourage walking. The nature of the transit product is such that if we could stop less often, assuming longer walk distances, we could achieve both better running times and reduced operating cost; the latter could be reinvested as higher frequency. So the two most fundamental determinants of transit travel time -- running time and frequency -- both depend on our assumption about walking distance.
With such basic things at stake, it's understandable that planners are always looking for ways to push walking distance wider. That may be the real reason that generations of planners have chosen to approximate a 400m walk with a 400m circle, even though every pedestrian knows how absurd that is.
I prefer to just have the argument in simpler terms. In Canberra, we pushed the walking distance standard from 400m to 500m, not because people were calling us demanding to walk further, but rather because we looked at how much more frequency and speed we would achieve, and the ridership that could attract, and decided that 100m of radius was a small price to pay for such benefits. It comes back to that graph near the top of this post, showing how far people walk to transit in different cities. There's no definitive authority for a 400m standard as opposed to 300m or 500m or even 600m. Yes, if you pick a bigger radius you'll lose riders from the outer edges of the radius, but on the other hand, you may buy so much travel time and frequency that your ridership goes up. As with everying else in transit, it depends on what you're trying to do.
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.
Let’s make just two assumptions about them.
Let’s assume (1) that the borts tend to form large assemblages, which enable trade, creativity, ritual, and whatever other activities give value to their lives. Let’s call these places cities. Since cities are places where borts are relatively close together, it follows that they have relatively little space per bort. Cities, by definition, are places where space is experienced as scarce.
Assume (2) that these cities are large enough that a bort can’t easily hop, drift, or slither around the city fast enough to reach all the needs and pleasures of daily life. Given this reality, they must have invented vehicles of some kind that carry them faster and further; if they hadn’t, their cities could not have grown so large.
Do we have to make an assumption about their communications? If the borts had either perfect telepathy or perfect virtual reality, then they would never need to move for any of the purposes of interaction. But in this case, why would they have cities? Let's assume [and I think this arises from (2)] that their communications are not so perfect, and that they do need to move around to do whatever borts do that constitutes their lives and economies.
Perhaps the borts have tried using a personal locomotion vehicle in their cities. It gives a bort freedom to move at high speeds, but it’s much bigger than the bort’s body, so it takes a lot of space inside the city. Given the city’s limits on space, these vehicles – which require a lot of space per bort – would have collided with those limits, causing something like congestion.
So (regardless of whether they’ve tried the personal vehicle) they must have invented a vehicle that can carry many borts at once for travel within their cities -- not to mention between them. Call it a bortmover.
But then comes the “network design” challenge: in a city where borts need to move around freely, from anywhere to anywhere else, what exactly should the bortmovers do? In what patterns should they move?
Well, they need to move in a known pattern, so that borts can predict them. That means some kind of routing and schedule, and a schedule implies both a frequency and a span of service. Borts need to get places soon, so that means that these vehicles must stop close to desired points of origin and destination, they must not require too much waiting, and they must be reasonably direct and also move at an adequate average speed.
So with only two basic assumptions about bort civilization, we can infer that they have concepts of stop spacing, frequency, span, directness, and speed.
Obviously, we can’t know what bortmovers cost to operate, but like all planets, the bort world is finite, so bort society must have a concept of scarcity. Even if bortmovers cost nothing to run, there is still that defining scarcity of all cities: the relative shortage of space per bort. Most likely there are other costs as well, reflecting the energy required to manufacture and operate the bortmover. So there’s some limit to the number of bortmovers, which motivates borts to use them efficiently.
Presumably, some parts of the city have a greater density of bort activity than others, so even if a bort’s likelihood of boarding a bortmover is constant regardless of location, there’s more bortmover ridership in these denser areas. So the borts experience a relationship between transit and density: if there are more borts within slithering/hopping/drifting distance of a bortmover stop, that’s a larger potential market, which means a busier bortmover.
So bortmover companies have to decide whether to route their bortmovers to maximize their ridership – which would mean no service to some of the more sparsely populated parts of the bort city – or to spread bortmover service across the whole city even though they’ll be crowded in some areas and lightly used in others. They’ve faced the choice between planning for ridership and planning for coverage.
They’ve also discovered that if they try to run a direct bortmover from every part of the city to every other, they get poor frequency and high complexity. Maybe the borts are all geniuses who love keeping complex networks in their minds, but poor frequency will still be an obstacle to getting where they’re going. So borts must have discovered the connection. That means they’ve faced a choice between connective networks (which are simple and frequent) and direct-service networks (which are complex and infrequent). And if they've tried to optimize a truly connective network, they've probably discovered the grid, regardless of whether their cities are grid-shaped.
Again, because space is scarce, they probably experience something like congestion. This problem will be worst where there are the most borts coming and going, but that’s exactly where the bortmovers are needed most, in high volume and with high quality. So perhaps some of the busiest bortmovers have been given exclusive linear spaces that they can operate in, so that they can run fast and reliably. Call them exclusive rights-of-way.
We don’t know much about the borts or their world, but with just two basic assumptions, we can infer that if they have invented transit, they have discovered the concepts of stop spacing, frequency, span, speed, directness, travel time, connections, and even right of way.
So bort transit must face the realities that we must face: Closer stop spacing, for example, means slower speed. Branching divides frequency. Straight lines are more likely to offer good travel time than winding ones, so the “be on the way” principle applies to bort communities as it does to ours.
In fact, almost all of the basic concepts of transit are realities of bort urban life, because they’re facts of geometry. They are true of anything we would recognize as transit, everywhere in the universe. They are not negotiable. So they should be the basis of our thinking about transit in cities, not a detail that can be left to the engineers. Cities must respond to the intrinsic geometry of transit, just as suburbia as responded to the intrinsic geometry of roads. And yes, you can use a cute, fun, or exciting transit vehicle, but that doesn't change any of these geometric facts. If you don't understand transit's geometry, technology won't save you.
Updated 18 Nov 2011.
A short draft chapter from the book, overlapping the content of this recent post but with an extended BART example that I hope readers will enjoy and have comments on.
Figure 1. Lower Mississippi River System, Drawn as a Transit Map (Daniel Huffman)
It’s a fun idea, but it also points to an important insight. If you travel upriver by boat, you expect the river to get smaller and smaller. Every time you reach a branching point, the volume of water in the two rivers in front of you is the same as the volume in the river behind you. If you keep going, you’ll eventually reach a river that’s too small for your boat. Transit is like that too, because branching always divides frequency.
This is one of those too-obvious points that’s easy to forget in the heat of a transit debate. For example, in 2003, the Bay Area Rapid Transit (BART) system opened a new extension to San Francisco International Airport (SFO) and also to Millbrae, an important connection point with the Caltrain commuter rail system. The basic extension, southward from San Francisco, looks like the top image in Figure 2.
It’s a triangle, with tracks from San Francisco to both SFO and Millbrae, and also direct tracks between Millbrae and SFO.
If you’re unconsciously thinking like a motorist, looking at this as though it were a highway map, it looks fine. All the points on the map are directly connected all the others. But transit can’t run all these connections at the same high frequency, because of the effect of branching. The actual pattern of service will have to be one of images beneath it. In these images, line-width represents frequency.
Figure 2. BART San Francisco Airport (SFO) Terminus
For example, suppose you want service every 10 minutes to both SFO and Millbrae, but you can only afford 10 minute frequency on the line through San Bruno and on to San Francisco. You have to run one of the two ‘sequential’ options in the upper left of Figure 2, either run all service to Millbrae via SFO, or all service to SFO via Millbrae. Either SFO passengers or Millbrae passengers are going to hate you.
Alternatively, we could branch the service at San Bruno, sending half of it to SFO and half of it to Millbrae. But the branching will cut our frequency. If we can only afford 10 minute frequency through San Bruno, then we’ll end up with 20 minute frequency at SFO and at Millbrae.
Finally, we can run everything every 10 minutes by forcing a connection. One side of the loop would have a shuttle train, while the other would have through service.
There is one other option, though it’s not available for BART. You could split the train in half, and send the front half on one branch and the rear half on the other. This is very tricky; it requires a driver in position ready to take half of the train when it arrives. It’s also hard to separate a train without at least a minute or two of delay, at least for the rear half of the divided train.
To sum up, we should suspicious whenever we see a branch drawn as though one line can effortlessly divide into two equal lines. Often, such a branch will be called an extension, a very slightly misleading word because it suggests that an existing, known quantity of service is being extended. In fact, a branch always means one of three things. Either
Geometrically, it has to mean one of those things, and it may not be the one you prefer. So before you decide whether the service is useful to you, or whether you support a proposed transit project whose map looks like this, you may want to ask which of those it is.
[i] A collection of these spanning most of the US’s major river systems is at http://somethingaboutmaps.wordpress.com/river-maps/
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.
Often, I use this blog and its comments to refine my own thinking about transit in the abstract. This is part of how I cultivate my own expertise, but it is easy to mistake what I say for activism. When I say, for example, that some of the widespread claims about the superiority of rail over buses are cultural feedback effects, I'm not thinking like an activist or advocate; I'm thinking theoretically, like a philosopher. To me, this is a crucial skill for a consultant who's going to have to marry his client's values with his own expertise.
Philosophical or scientific training attunes you to the difference between prescription (telling people what they should do) and description (describing reality as it appears to be). In their purest form, prescription is the job of ethics, while description the job of science and metaphysics. A great deal of human speech, especially political speech, is a mixture of description and prescription, often one pretending to be the other.
In the planning world, prescription is the job of citizens, leaders, and advocates, while description is the work of professional experts like me. Obviously, this has to be a conversation. The expert has to ask the community to clarify its values based on the actual tradeoffs presented by reality, and the community has to respond. And as that goes on, both sides need to be clear about their roles, and respect the role of the other.
Partly because of my science and philosophy training, I tend to police the prescription-description boundary in my own thinking, and dwell in the space of pure description more than many people do -- certainly more than most activists do. A lot of regular readers of HT share that training and that inclination, and some don't.
For a critique of the futility of living your whole life in this descriptive mode, watching and describing the world but never doing anything, see Shakespeare's Hamlet. But the opposite is also futile. An ethical system devoid of curiosity about objective reality devolves into pure egotism, such as that of the tyrants currently falling across the Middle East. Tyrants -- whether they lead a nation or an office clique -- are people who sift reality and see only what suits their ethical narrative (which, at that point, is really an egotistical narrative) and who forge echo chambers of people who help each other do that. At the core of the tyrant's stance is a childlike egotistical wail: "Why doesn't everyone do as I say? I see so clearly what needs to be done!"
And yes, everyone has an inner tyrant, including me. I try to describe that tendency in myself, so that while it will always be in the room of my mind it's not usually able to set the room on fire. In fact, that's exactly why I'm so careful about not letting my descriptive thinking turn too quickly into prescriptions.
Streetcars, for example. Nowhere in this blog have I said that cities shouldn't build streetcars if they are sure that they want streetcars. Some streetcar advocates hear me saying that because they are dividing the world into pro-streetcar and anti-streetcar camps, and I've said things about streetcars that don't sound like enthusiastic advocacy. I've made some descriptive observations about problems raised by the American streetcar revival movement, and I've also noticed situations in which streetcars are inferior to buses in their ability to actually get you where you're going, like this one:
I would like people to know about these issues so that they make better decisions about what to advocate and why. That doesn't mean I want them to decide not to build streetcars, but it may mean, for example, that in deciding whether to support a streetcar, you might need to care about whether it will be in mixed traffic. It may also mean being very clear, when you're advocating a streetcar, that you're not getting anything faster or more reliable than a bus can be. Again, I say this not because I think cities should or shouldn't be building streetcars, but because you shouldn't be deluded about what you're buying, and what purposes it will really serve.
I have vivid memories of San Francisco Transportation Authority meetings in the early 1990s when the Third Street light rail was under debate. Activists from the neighborhood had turned out in droves to support the line, but when you actually listened to their testimony, some were talking about "we need rapid transit," while others were saying "we need rail to stop in every block where it will strengthen our businesses." I knew, as an expert, that while this whole crowd appeared to be on the same side of the issue at hand, half of them were not going to get what they thought they were advocating. They were not going to get a project that served their values.
I may also point out that if you think purely about "extending your rail network" as though your bus network is irrelevant, you can do serious damage to your existing transit system. For example, in a high-frequency grid, if you break one line of the grid into three consecutive pieces because you want rail in the middle but buses on the extremeties, you may suddenly force many new connections to a degree that could quite possibly will reduce the overall level of mobility in the city. That thought is relevant, for example, to several cities' streetcar plans, and to the Crenshaw light rail line in Los Angeles, and to the Gold Coast light rail line (at least its first phase) in Australia.
And yet, sometimes I do sound like an advocate -- about transit in general, about protecting transit from traffic, and about congestion pricing. Am I just falling off the wagon when I say those things?
Well, all scientists (by which I mean broadly "people who try to describe without prescribing") have this problem. Sometimes the scientific work of description discovers that something needs to be done if we want to survive and prosper: Banning DDT, addressing carbon emissions, correcting perverse pricing signals, even building a transit line. If you've followed any of the conversation around climate change, you know how uncomfortable trained scientists can be when they're required to speak prescriptively. Their credibility (not just to their profession but also to themselves) has depended precisely on not doing that. It's like telling a recovering alcoholic that after all the disciplined work of recovery he's done, the future of humanity now requires that he start drinking again, just a little.
All I can say is that I feel that discomfort and try to manage it, by marking, as clearly as I can, when I'm prescribing and when I'm describing. And there are also issues (like climate change) where, quite frankly, practically all experts seem to know what needs to be done to achieve the outcomes that everyone seems to want. I feel that way about congestion pricing. It's just not that hard to explain, to a reasonable person who's familiar with the idea of supply and demand, that as a motorist you are going to pay for scarce road space in either time or money, and that it's not unreasonable for some people to choose to spend money to save time.
I do what I can to distinguish between description and prescription when I'm writing. But frankly, we all need to do the same work when listening. If your first contact with transit politics is in the context of a fight about whether or not to build a particular rail line, you're going to hear prescriptive voices on both sides, citing data that's been selected to match their point of view. You're also going to hear descriptive voices treated as prescriptive -- which is how some streetcar advocates perceive my comments about streetcars. One of the most basic disciplines that you can cultivate, as an advocate or leader, is to try to hear descriptive information as descriptive. This may require you to consciously suppress or bracket the emotional reaction you have, as an advocate, when you first hear it.
Really, none of what I've written about streetcars is about streetcars, except insofar as the American streetcar revival movement is a excellent example of a descriptive point that seems important to me. The point is that "it's possible to spend a lot of money on transit lines that don't improve anyone's mobility." I'm not saying you shouldn't do that. I am saying that before you that, you should understand this point, so that you're sure that the line you support does what you want it to do.
That's what responsible experts do: they help you implement your values.
Leigh Holcombe's email pointing to Huffman's work is fascinating timing, because I was just about to write a section of the book on how branching dissipates frequency.
Really, these fanciful maps are a bit reminiscent of some real transit maps, aren't they?
Metlink's map of the Melbourne train network has important things in common with a river system map. First, both networks are radial, which means that all lines converge to flow to a single point (New Orleans for the Mississippi River, the City Loop for Melbourne's trains). And necessarily, both maps are full of branching:
But branching always divides frequency. The Melbourne map gives a superficial impression that Lilydale, Boronia and Ringwood all have the same kind of transit service. They certainly all have train stations, but the branching means that Ringwood has to have more frequent service than either branch, and that may be the difference between a service that can be used spontaneously and one that requires you to build your life around a timetable.
It's interesting to speculate how transit policy might change if everybody was trained to be suspicious whenever they see this ...
... because this always means one of three things. Either (a) points beyond the branching point have less frequent service or (b) one of the branches operates as a shuttle, requiring a connection, or in a few rare cases (c) the train itself comes apart, with some cars proceeding along one branch and some along the other. Geometrically, it has to mean one of those things. And before you decide whether the service is useful to you, or whether you support a proposed transit project whose map looks like this, you should ask which of those it is.
I've always been partial to mapping styles where a branch is rendered as a wide line splitting into two narrow lines, such that the width of the two narrow lines adds up to the width of the main line. In my presentation "A Field Guide to Transit Quarrels," I used that approach to clarify one of the possible branching patterns of BART's San Francisco Airport line (though this is not the pattern that runs today.)
Because in that respect, transit lines really are like rivers. Just as two converging rivers combine their volume of flow, two converging transit branches combine their frequency.
Sometimes, we have to think in triangles.
In the transit world, for example, we know that ridership arises from a relationship between urban form (including density and walkability) and the quantity of service provided. For example, if we focus on local-stop transit, the triangle looks like this:
You can think of development and service as inputs, and ridership as the output, but you can rotate the triangle any way you like. For example, if you want to justify an increase in service, you want both some existing ridership success and also evidence, from the development density, that there's more potential. In other worse you want to say "Ridership + Development --> Service" On the other hand, if you want dense development as an output, you want a transit line that feels permanent. That's going to be one that already has high service, achieving high ridership. "Service + Ridership --> Development." (In each case, the right-arrow means "supports" or "helps to generate" or "is one of the crucial necessary conditions for")
I am reminded of this triangle because transit discussions are full of assertions about the relationship of two points on this triangle. Some of these are quite famous. Pushkarev and Zupan, for example, are dutifully cited in every article that deals with this topic. WIth a publication date of 1977, they are one of the oldest must-cite authorities in transit research; it's as though they've passed over into the realm of scripture. Their conclusion? "A net residential density of 15 units/acre supports a service level of 10 minutes or better over a 20-hour span." This is a stated relationship between two of the three points on this triangle, service and development, without reference to the third, ridership. So hidden inside the verb "supports" is an assumption about what level of ridership is acceptable.
There is, to my knowledge, no agreed standard about what level of ridership is acceptable, nor should there be. Every city or agency decides that for themselves. That means that logically there can be no answer to the question "is development pattern and density x sufficient to suppoert service level y?"
In the British-influenced world, of course, there's often a hidden implication that the ridership standard should be "profitability." Certainly, if that's your goal, then you've fixed that variable and can now look more coherently at the relationship between the other two; in other words, it then becomes coherent to ask "what service level should be offered in response to each development type, so as to hit a goal of profitability." (Yes, fare policy plays a part, and that's still another variable, but you can also choose to hold that constant.)
But of course, most of us don't think transit should aim for profitability. A profitability paradigm assumes that government has no public interest in the success or failure of transit, just as it has no interest in the success or failure of Coke Zero. And obviously that's wrong.
So when I hear people either quote or update Pushkarev and Zupan, saying that density x supports what level of service y, I hear pure incoherence. The statement says nothing that's useful to me. What am I missing?
UPDATE: Jeffrey Zupan himself wants to assure us that his work was based on a clear ridership assumption, expressed in the form of targets for cost/passenger and cost per passenger mile. Unfortunately, most people who quote his work forget that part. In doing that, they're implying that the ridership target that Pusharev and Zupan chose is the right one for their own community, even though they don't know what it is!