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