Monday, April 2, 2012

The 4 "Blind Spots" in Transportation Planning

We live in a highly rational, cartesian world. One where a formula and a calculation is necessary to accomplish anything. Economists and engineers have reduced everything they do to simple and not-so-simple calculations under the guise of objectivity. "Why you can't argue with me, it isn't me, it is the formula. And that formula is God."

Of course, we're seeing what happens when you reduce a world of complexity into a world of abstraction. Messiness is left out. Externalized. "Oh, we can't quantify that. That might be subjective and therefore a variable, so that is left out of the equation." Cities and economies are highly interrelated. In fact, the city is the physical manifestation of the economy. And both are thus fractals.

A fractal is an entity of infinite complexity but guided by simple rules. Repeat said rule a million times and because of the interrelations, an altogether new physical entity appears. By economists externalizing certain aspects of the world or transportation engineers doing the same within their demand modeling formulae, and thus repeating them over and over and over millions of times, we begin to see the catastrophic and complete systemic failure of both the economy and the way we build our transportation system, therefore how we build our cities is broken at its very core, producing something altogether different than has ever been seen before in the history of civilization. In effect, the anti-city.

When complex systems, such as fractals diverge from a stable state and then repeat that divergence over and over again, we get a dynamic known as bifurcation. The inherent self-organization and complexity becomes ever-increasingly distorted until it becomes chaotic. Modernist city planning changes the rules of the game, how cities evolve and emerge, between Euclidean zoning, minimum parking standards, and most importantly transportation planning/demand modeling. It instilled bifurcation and we've entered a state of chaos, or anti-city.

It is inertia and entropy played out through misguided institutionalization.

Image via Urbagram. Haterz to the left. Chaos to the right.

As I mentioned earlier, one of the key failures in our process of city building is in transportation demand modeling. In fact, I suspect this has been one of the alterations to our urban DNA most to blame for turning the physical organism of cities into a mass of oozing goo as if it were something out of Dr. Who.

If you've ever wondered why more capacity is the only solution transportation planners only, I will explain the 4 Blind Spots where transportation demand modeling, practiced by every transportation agency from NCTCOG to Texas Transportation Institute, fail to account for certain reductions, and therefore externalize...reality.

Fundamental Purpose of streets and movement:
They are simply trying to move cars. As Lewis Mumford accurately surmized, "...our experts in transportation are kept by their own stultifying axioms from realizing is that an adequate transportation system cannot be created in terms of any single limited means of locomotion however fast its theoretical speed."

The theoretical speed part is important and a false goal that can never really be achieved. We've established Level of Service grades based on whether there is a free flow of traffic or not. Unfortunately, any place that is desirable in any way, shape, or form is going to become crowded. So they build places entirely undesirable to ensure nobody wants to be there. Their system works best when there is only one car on the road, not more. That is the optimum condition. Not more. And therefore it completely misunderstands and thus undermines the real purpose of movement within a city as it strives for an impossible goal. However, it does succeed admirably in successfully creating inhumane, soulless, undesirable places.

As Mumford continues, "the purpose of transportation is to bring people and goods to places where they are needed, and to concentrate the greatest variety of goods and people within that limited area, in order to widen the possiblity of choice without making it necessary to travel. A good transportation system minimizes unnecessary transportation [ed. note: and infrastructure]; and in any event, it offers change of speed and mode to fit a diversity of human purposes."

The purpose of the city (and its infrastructure) is social and economic exchange. Transportation planners actively work against this fundamental purpose and whence repeated ad infinitum, the result is not city, but anti-city. And it is doomed to fail. And fail catastrophically.

Induced Demand:
When a road is congested the traffic engineers will inevitably suggest more capacity. More capacity with similar demand means the road will flow better. Unfortunately, they're missing two aspects: 1) demand doesn't remain the same and 2) sometimes congestion is a good thing. Urban congestion is a bit like cholesterol. There is good and bad kinds. If it is all in cars (LDL), it is the bad kind and it can kill an area. If it is of the good kind (HDL), the pedestrian kind, it makes an area healthier, more vibrant, more sustainable.

But back to the first part of demand. What they don't factor in is a concept called induced demand. A University of Toronto study however did quantify this effect. What they found is a 1 to 1 relationship between increased road capacity and Vehicle Miles Traveled. This means that, let's say over a 20 year span, if road capacity doubled in an area, then the distance people were driving also doubled. People moved further and further out, diminishing tax base, the synergistic value of city, and once again turning "city" into "anti-city."

A similar study from Brown University found that with every urban highway, a city experienced an 18% loss in population, thus substantiating the effect that new roads mean people further and further apart. In other words, if you build bigger roads, they will just fill up again. And even if they don't, you might have a bigger problem because then you have the burden of unnecessary infrastructure. Either way, the city loses.

Reduced Demand of Walkability, Propinquity:
Also not factored is the change in travel mode in varying degrees of density and urbanity. The traffic demand model simply inputs the amount of residential, retail, or office space and each of which spits out a number of expected traffic trips needed. This then tells the transportation planner how big the road needs to be. How many cars will be on this road at any one time. Again, it doesn't calculate whether these people might choose other forms of transportation.

What we've found working in a variety of urban and suburban contexts, creating unfortunately isolated bubbles of walkable urbanism within a sprawled, automobile-based context, is that there are tiers of car-trip reductions based on context and density. Transportation planning is focused on the suburban model which thus induces every trip as a car trip. In walkable suburban locations (like Legacy Town Center), we've found an approximate reduction in car trips of 20%. In walkable urban environments (like uptown Dallas), we've found a reduction in car trips of 40%. And since there are certain places which can be entirely car-free, ie even more urban, those numbers are likely just a base line. But they are a start. And they aren't factored into transportation planning and projections.

The Rise of the Internet:
I wrote a piece about a year ago for Columns magazine about the Professor Peter Newman's theory that cities are always the product of the latest transportation technology. In it, I suggested that we are moving out of the period where the car is the latest and most useful piece of interconnective technology and into a period where the internet is (in a way). The car requires extensive infrastructure which is often corrosive on the dynamic of an interconnected city when you prioritize it and only it.

The internet allows for regional trips to be reduced, but not simpler, easier, cheaper, more desirable trips, ie walking trips. We still like to and need to make those. However, if we ever decide to shop online rather than driving to one of the last remaining regional malls to do our shopping that is a saved trip. The rise of the internet and the associated reduction in regional trips is not factored into their calculations. Nor could it probably ever be. And that is half the problem.