Revised Development Projections

I've been working on a revised version of the development projection images that I did a while back.  I wrote a long post about it on Stat Chat that has the full images and some commentary on them.  Here I wanted to explain a little more of the technical background on how I made them.



How Is This Constructed?

The model starts with a random value in a Poisson distribution that simulates the likelihood of development.  This distribution captures the fact that some parcels will develop seemingly at random.  As different circumstances change, more and more areas will develop until finally the vast majority of land in an urban area will develop.  After that, some undeveloped plots will remain for a while and a few will simply never develop.

The values in this raster are then raised by adding a score based on the driving time to major employment centers.  This is because most development is and has been automobile-driven.  The shape of an urban area is highly predictable based on the driving time to an employment center.  Lastly, I reduced the likelihood of development based on the slope of the terrain and subtracted all national and state parks, wetlands, military bases, conservation easements, and local parks that were in some way preserved.  I then split this model up into planning district commissions because they roughly encompass metro areas that expand outward from a core.

The density that I used was the same density of development in the district that I was adjusting.  So if the developed areas of a planning district had a density of 1000 persons per acre, that's the density I used for the predicted new residents also.  These densities are likely to be off because of several factors.  They could be too high because, while areas have been gaining population over the last 50 years, the existing population has also been decentralizing and new residents are likely to buy the lowest density homes on the periphery.  On the other hand, they could be too low because, as areas grow in size, they become denser and each new person's marginal amount of developed area is a little smaller.  Additionally, the trend in recent years has swung the other way, as I pointed out earlier in the post.  For lack of a better model, I considered it a wash and stuck with the existing density.

Cities and driving distances:

Slope:

Conserved land:

Growth likelihood raster and planning district boundaries.  Some counties are shared by planning districts - I had to assign these to one district and deduct their population numbers from the other.

I'd be very interested to hear of ways you think this could be improved or additional factors that could be added in.  One I thought of was buffering around the Chesapeake Bay and other bodies of water to account for the attraction of living by the water.  Another is doing a more comprehensive service area just around the roads to get more of the development aligned with roads rather than "speckled" about.  The problem with that is that new developments come with new roads and you don't know where they're going to be.

MSA's and Commuting

New post on Statchat looking at the dependence of rural counties on nearby urban areas.

Percent of workers commuting to the Washington, DC area:

Wahoowa!

In Which I Acquire a New Toy

Namely - Tom Gross's cartogram script for ArcGIS. 

Virginia counties distorted to make area correspond to population:

Where you from?

Why do Hampton Roads and Northern VA seem so different from the rest of Virginia?  At the macro level, it's pretty obvious - the influence of the Federal government in DC and the military in Hampton Roads.  But it's even more obvious on this map, which shows the percentage of the population born in Virginia.  Blue means born here, red means born elsewhere:

Percentages are high in Hampton Roads - especially around military bases.  But almost the entire northern Virginia metro area is in the red.  Fewer than 30% of NoVA residents in most areas were born in Virginia.

Here's another map showing the percentage of the population born outside the U.S.  See the Weldon Cooper Center's post on immigration for more on this subject.

A few quick regressions on excel shows a pretty strong link between places that have more bachelor's degrees, more people born outside VA, and a higher income.  It's not a particularly new revelation - the more education and earning power a person acquires, the more geographically mobile they become.

Tract Facts

Nothing too special here in the way of analysis - was just curious about a few subjects so I thought I'd throw them onto a census tract map.  The roads are interstates to help you get your bearings.

Percent of population 25 years and older who have a Bachelor's degree or higher:

 Adults that are currently married:

 Percent of population who moved in the last year:

Sprawl: A Compact History

I am currently reading Robert Bruegmann's well-researched screed against the planning establishment's complaints about sprawl.  It's an excellent read and a tremendous hairshirt for all students steeped in planning school dogma.  In the end, though, his arguments succumb to many of the same historical reductions and internal contradictions that he is decrying in others.  Just a few great quotes that stuck out to me:

"It is possible that even when a small, remote star explodes, this event can reorder the entire gravitational system of a galaxy. A slight wobble in the axis of a planet can mean drastic warming in one area and cooling in another. So it is with urban systems, the main difference being that the most basic element in the urban system is the individual human being who can think and make decisions. Any change made by any member of any neighborhood affects, to some degree, everyone else in the metropolitan area."

p. 94

"The term 'sprawl' has never had a coherent or precise definition.  This has been one of the reasons it has been such a powerful polemical tool.  Thinking of it as a blank screen on which a great many people project their own feelings of discontent with contemporary urban conditions is a good way to approach the history of the anti-sprawl movement.  Because of the lack of a precise agreement about what sprawl is, individuals have been free to rally around certain broad but quite abstract concepts as a way to explain what is wrong with developments they see around them without necessarily agreeing on any specific diagnosis of the problems or any concrete set of prescriptions.  It has allowed people with radically different assumptions to find common cause."

p. 115

"The same homebuyers who might try to maximize their personal advantage in buying a suburban house are the voters who elect government officials and who push for land-use regulations that will benefit them, often at the price of other parts of the population.  Is it logical to think that landowners would suddenly act in a completely different fashion when they engage in political rather than economic transactions?  Nor is the kind of behavior that puts personal interest above community welfare peculiar to low-density settlements.  The resident of a central city who tries to block the badly needed expansion of a hospital next door to his apartment building because it would block his view is acting in a similar fashion."

p. 99

"Affluent residents of Youngstown who move to the exurban fringe are merely exploiting one of the most important assets available in the metropolitan area - a large supply of attractive land at low prices.  Although at first glance it appears that the dispersal to the edges does little other than eviscerate the central cities and displace agriculture, in many cases, the possibility of building a house on a large tract of inexpensive land in the exurban fringe is the one thing that continues to attract middle-class residents who might otherwise flee to more dynamic regions.  If, as is quite likely, Youngstown's downtown and central residential districts revive, it will not be despite sprawl but because sprawl has made it possible for the metropolitan area to retain residents during extremely difficult years."

p. 89

"In the early years of the 21st century, it appears that the forces of renewal and gentrification are becoming dominant in an increasing number of central cities.  The old 'crisis of the central city,' in which jobs were departing and property values plunging, could well turn out to have been a short-lived phenomenon...

Many smart growth activists believe that as people return to the city in greater numbers, this movement of people will create population gains and an increased density that will reduce the pressure for outward expansion.  Increasingly,  however, as affluent citizens have moved to the center, they are doing just what their counterparts have long done in the suburbs.  They have found that they can use zoning ordinances, historic preservation measures, environmental regulations, and other means to resist continued change, to control the appearance and character of their neighborhoods, and to stop densities from rising.  In city after city, the old zoning codes have been downzoned time and again to reduce the ultimate possible population and prevent existing densities from rising."

p.57-58

"What few people seemed to notice was the way the rising fortunes of the center, like their earlier decline, were directly connected to developments at the edge.  As more and more businesses and people, including even some of the least affluent members of the urban community, arrived at the urban periphery, it lost much of its exclusivity and social cachet.  The number of individuals at the very top of the social ladder who wished to buy large houses in the farthest subdivision declined dramatically in the last decades of the twentieth century.  As this happened, the central city and older established suburbs began to regain some of the luster they had lost in the postwar decades.

One of the ironies of this revival is that while central cities have traded on their 'traditional' character, much of what is most attractive about them is the fact that so many of the things that once defined them have disappeared.  The decanting outwards of all kinds of manufacturing and warehousing functions led to dramatic reduction in street congestion, truck traffic, and pollution.  This allowed city centers to become increasingly attractive to those who have the choice to live anywhere they wish in the metropolitan area and  who in previous decades might well have chosen to live in the suburbs or exurbs."

p. 53-54

- Robert Bruegmann

More Pavement

I continue my quest to be the Ken Pomeroy of impervious surfaces.  Here's a nicer visual with new data from Lynchburg and James City County, giving us a much smoother and more indicative index - from dense city to mixed city to suburban county to suburban/exurban county.

Four reasons bikes should not pay the same fines as cars

Thanks to Brian Davis at Cville Tomorrow for publishing this.  The link is here.  I've edited the manuscript a bit as a result.

Bike tickets are on the rise and they carry the same fines and legal consequences that vehicle infractions do.

This system is a bad one for four big reasons:

1. The cost of a ticket is disproportionate to the cost of riding a bicycle

The cost of a traffic ticket is scaled to the cost of owning and driving an automobile.  One ticket costs about as much as it costs the average American to own and drive a car for a week.  That’s enough to be a reasonable deterrent, but not an unreasonable expense for someone paying an average of almost $8,000 a year to own a car and drive it.

For most riders, bikes are a cheaper alternative.  They are a way for people with less disposable income to get access to some of the same opportunities as those who can afford to drop money on cars, gas, and parking.  They allow people to trade comfort and some speed for savings and exercise.  Getting a bicycle ticket threatens this trade-off immensely.

While $150 is a drop in the bucket for a car owner, it may be half the cost of a bicycle and more than it costs to ride a bike for a year.  That’s a huge risk.  A ticket a year only slightly raises the cost of driving.  A bike ticket a year makes biking almost not worth it, putting another car back on the road or depriving someone of reliable transportation.  Compare it to the outrage drivers felt in 2007 when the state legislature tried to increase fines by 700% to make up our traditional transportation budget shortfall.  The costs were simply unreasonable for drivers to absorb in comparison to the other costs of driving.  Current ticket prices for bikers are just as unreasonable.

2. Bicycles are not 2-ton blocks of metal that go 70 mph and kill thousands of people a year

Fines are high for traffic violations because traffic violations are a big deal.  Cars kill over 30,000 people a year in the United States and injure hundreds of thousands of others.  Cars are weapons that can do serious and expensive damage to others on the road – including cyclists, whom they kill at a rate of over 600 a year.

Bicycles, to put it simply, do not.  The dangers posed by the two modes are several orders of magnitude apart.  As much as drivers may rail about the behavior of bicyclists being unsafe or causing accidents, there are almost no recorded incidents of a vehicle occupant being injured because of the actions of a bicyclist.  You have a better chance of becoming President of the United States than of getting hurt by a bicyclist while you are in a car.  The only people reckless bikers put in danger on the road are themselves.

Bikes can be a danger to pedestrians, especially if ridden on the sidewalk.  Yet they still injure pedestrians much less frequently (and less severely) than cars do.  By comparison, around four thousand pedestrians are killed by cars every year and tens of thousands are injured.

3. It is often difficult for bicyclists to follow the rules safely

We are not yet at the point where cycling according to the rules is an easy feat.  Many traffic signals only change when a car pulls up to them.  Rocks, glass, snow, and other debris in bike lanes often force bicycles to swerve in and out.  When they do so, they risk being charged with “reckless driving,” a widely abused citation for cyclists.  Coming to a complete stop rather than a rolling stop at stop signs forces cyclists to put a foot down and waste additional time starting again, angering motorists behind.  Cyclists can get tickets for failing to signal turns, which is often unsafe.  While signaling, the cyclist risks losing control of the bicycle as well as the ability to brake with that hand.  These and other problems are not insurmountable, but the roadway is still a harsh place for bikes.  The rules are not as tailor-made or easy to follow as they are for vehicles.

4. Motorists are almost never held responsible for collisions with bicycles

Negligent drivers who injure passengers in another car can expect to pay hefty insurance bills and potentially face legal consequences.  But if they hit or even kill a cyclist, there are rarely any consequences at all.  Read Daniel Duane's excellent op-ed in the NYT: "Is it ok to kill cyclists?"   It's a nationwide issue, but Virginia is a particular offender.  We are consistently unable to get even common sense protections for bicyclists on the road, including a shameful vote in committee last month to kill a bill protecting bikes from "dooring."

The Economist has this to say about American traffic laws: "[M]otorists in America generally receive no punishment whatsoever for crashing into or killing cyclists, even when the accident is transparently their fault. This insane lacuna in the justice system reflects extreme systemic prejudice by drivers against cyclists, and would be easy enough to fix."

The only place where cyclists are treated as equals is when being fined for traffic violations.

The solution: better infrastructure, better laws, rescaled fines

Bike lanes and separated cycle tracks are the only way to make cycling truly safe and effective as a means of transportation.  In the meantime, we need two things:

1. Amended rules for cyclists that allow them to use their natural advantages to everyone’s benefit and grant them the same common sense protection given to every other type of vehicle.

2. A scaled-down fee schedule.  Moving violations should cost about one tenth the equivalent vehicle fine to reflect the difference in cost of ownership.  Most bike tickets should range from $10 to $20.  Before this can work, Virginia needs to fix its absurd system of flat “court costs.”

If we scaled down these costs and fixed our bicycle laws, then I might be in favor of handing out more tickets.