Recently in Social Networks Category

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In short, I have turned comments off on this website.

Since the middle of our brief sojourn in the 21st century, social media has exploded. Facebook has peaked (by which I mean, of course, my use of it has peaked), Twitter is still on the rise (by which I mean, my use is continuing to increase). Overall we may have passed Peak Blog (although we just may be in the Trough of Disillusionment).

Many people read this blog from an RSS feed (usually Google reader or some frontend for Google reader: I use Reeder on the iPhone and PerfectRSS on the iPad and Google Reader on my computers).

Others see posts on Twitter. Some actually come to the blog website itself. A very small fraction post comments. A slightly larger fraction see them (those who click to comment themselves, or come to the blog via Twitter, but not those who read it on RSS or even the website, since unless you are sharing the post, or explicitly want to read comments, there is no reason to click through to the page). I wish everyone would just use RSS to read links and we could be done with it. But that is not the world we live in.

Most of the few comments were useful. A small fraction of prospective commenters also complain to me the commenting system is painful or broken. This blog is a MoveableType blog administered by the University of Minnesota UThink service, so I have very little control over the system. Authentication is aimed to reduce spammers, which it does at the cost of annoying non-spammers (Security is the enemy of efficiency).

The Transportationist was never really intended to be a community, though of course it has its partisans. I am not making a living off my blog (or from book sales) so I have not done much in the way of SEO or attempting to drive traffic. My blogging earns no academic credit, it does not appear on my CV, and is probably viewed by colleagues as a distraction or waste of time. At best it earns me fame, at worst, infamy. Given the number of readers (which can be measured in Micro-Grubers), I doubt either is the case. I doubt I got any research projects funded due to blogging. My views are eclectic on the conventional political axes, and so no one is really sure if I am on their team.

Where else I write:

  1. Books (and Wikibooks) [In engineering, Books earn almost no academic credit. You should read (and write) them anyway.]

  2. Articles and Reports - Typically in peer reviewed journals, at conferences, or working papers, linked to on my website.
  3. Streets.MN - Approximately biweekly, approximately 1000 words, approximately on something transportation-land use related in Minnesota.
  4. Twitter - Public, but short, usually for links ... this is where the energy on Linklists has gone. Some have noted that there are a lot less linklists than before. This was about a 1 year experiment. I know it was relatively popular, but the effort was high, higher than it should be due to the wrong tools. In particular, if I read on an iPad, it is a pain to share a link via the blog (my workflow entailed emailing it to myself, loading the link on my desktop, sending that to the blog), but quite easy via Twitter. Since much of my blog reading has migrated to 5:00 am in bed on an iPad, this is how it has worked out. Twitter also gets a twitterfeed from my blog, since by definition, everything I write here I think is link list worthy.

    There are also a slew of other blogs (TransportationNation, The Other Side of the Tracks, Autoblog, Politico: Morning Transportation, etc.) that do similar link lists (I know a few follow me), so my value-added here is fairly low, maybe catching an interesting article or promoting a story earlier than it otherwise would be. They are paid for this, I am not.

    Anyway, if you like my curation of links, follow me on Twitter. The reason I do this is mainly for my future reference rather than what I think others are interested in, but if you are interested in some of what I am interested in, it will work for you.

  5. Emails (one to one or one to few conversations). I try to keep these as brief as possible. In some cases, down to a single letter (Y, N). If you don't ask an explicit question requiring a response, you may not get a response.

And then there are the Other Social Networks:

  1. Facebook. I used to automatically feed my blog here, but it stopped. I just it started again with Twitterfeed. I assume most people will ignore or block me. I occasionally comment on someone's post, or like something. I don't know why. I occasionally post pictures of the kids, but I am torn between that and Flickr, and lately Flickr gets more love. If I know you in real life, feel free to FB me.
  2. LinkedIn. I still don't know what it is for, but I have lots of contacts. I don't write here and stopped feeding the blog here when they had some technical issues (posting a picture of Jenny McCarthy with my post). I just started again with Twitterfeed, since there are a few readers there. Feel free to Contact me there.
  3. GooglePlus. I send my posts to Google+. I don't know why, though there are a few readers there. Feel free to Encircle me there.

The Transportationist dates from April 2006 (notably post-tenure). So what is the purpose of The Transportationist: It is temporally random, featuring posts of random length but almost always less than 5000 words and often less than 500, generally something transportation-land use related or an announcement of something I or my students have written or edited elsewhere, or a conference, or a talk, etc. In short it is my and my research group's blog (but I am solely responsible for its content). It is not a community website, or intended for comments generally (in contrast with e.g. Streets.MN), though some posts in the past have drawn quite a few. If you think what the blog says is interesting, follow it. If not, keep calm and carry on.

If you have comments, you should get a blog (or if you have one, post there). As someone on the web remarked, that will get a lot more attention for both of us due to Google's PageRank formula than posting on comments with a nofollow tag. If you think I should post something, feel free to email me, I sometimes posts "A reader writes" type of posts, or "A reader responds". Let me know if you prefer anonymity from the rest of the world, but I still need to know who you are.

Another complaint about comments. I don't much like anonymous speech (though I understand the need in the case of totalitarian dictatorships, that is not the situation here). Most comments are anonymous. If I ever migrate to a new platform, I will reconsider. As someone said, never read the bottom half of the internet. Also don't feed the trolls.

If you want to get in touch with me, there are lots of channels, frankly too many. Email is probably best. You are smart, you can find it.

So if you are still with me, thanks for reading to the end of the post.

Newspaper Advertising


The Transportationist just loves him some S-curves. This via Business Insider: CHART OF THE DAY: Newspaper Advertising It is self-explanatory (and speaks to dematerialization and substitution of the electronic for the physical).

I have about 20 phone numbers in speed dial, over 200 Facebook "friends", almost 300 Twitter followers, over 600 LinkedIn Connections, and over 2000 people in my address book, but I know of many others. The deaths of Ernest Borgnine and other celebrities and politicians reminds that I know of a lot more people than I know, as I would be truly sad if people I actually knew died as frequently as celebrities.

I really don't know how many people I know, or know of.

We can estimate though.

Unscientifically, I seem to recognize about 3 celebrity deaths a week (including politicians, athletes, academics, and others I have heard of). (You can check this for yourself at wikipedia's Deaths_in_2012 [It might be closer to 2, in which case you can adjust the numbers accordingly]) If we assume this is steady state (I am sure it isn't), that is 52*3=156 deaths a year, or over the course of my 100 year life (I am an optimist), 15,600 deaths in my lifetime. This implies I know of at least 15,600 living people (ignoring leap years). The number of people I will know of when I am 100, avoiding senility, surely exceeds the number I know of at birth, so there are lots of nonlinearities to go around.

Of course I know more, because some celebrities will outlast me, assume half, so we add about 7,800 living people whom I will predecease.

There are many people whom I know of who died before me. Historical celebrities, politicians, etc. whose name I recognize. How many? If we assume all historic personages are in wikipedia (they are not, and certainly not all by year of death), I could go through that and make an estimate [See Deaths by year]. Of course it increases as we get nearer in time to the present (I know of a lot more people who died in 1966 than 66 AD, both because records are better in the present, and because there are far more people).

Let's assume that in the year before my birth, 1966, I am aware of 156 people who died, and in year 0 (i.e. 1 BC) I am aware of zero. That is not strictly true, as there are probably dozens of Romans, Greeks, and others whose name I would recognize, but collectively that would amount to under 1000.

So, if we do a straight-line interpolation (again I am sure this is wrong, but I don't know the exact shape of the function, and this certainly over-estimates), then I know 156 * 0.5 * 1966 people (1/2 base * height), which is 153,348 historic personages. WOW! (I should have been a great quizbowl player). We could assume a negative exponential function, and do an integral, but calculus is no fun.

I could adjust this by assuming I only know of 1000 people between 1 BC and 1000 AD, and then doing a straight line estimate from years 1000 to 1966, which would give 156 * 0.5 * 966 = 75,348. This too is likely an overestimate, but it gives me a plausible number.

OK, adding this all up

15,600 + 7,800 + 1,000 + 1,000 + 75,348 = 100748 people. So my order of magnitude upper bound of my estimate is 100,000. The real number is probably between 33,000 and 100,000.

This excludes the people I actually know, which is a mere fraction of the people I know of.

[Ernest Borgnine's best role was perhaps Marty, which we quote in Planning for Place and Plexus].

Cities or Solitude

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Susan Kain in the New York Times has a pro-Introvert article: The Rise of the New Groupthink: "SOLITUDE is out of fashion. Our companies, our schools and our culture are in thrall to an idea I call the New Groupthink, which holds that creativity and achievement come from an oddly gregarious place. Most of us now work in teams, in offices without walls, for managers who prize people skills above all. Lone geniuses are out. Collaboration is in. "

In contrast, there are many who believe that cities, the machines that enables those inter-personal interactions, are the source of creativity. This is epitomized by recent books by Ed Glaeser and Ryan Avent.

We can make a simple table:

City Country
Introvert Optimal amount of stimulation if quite space,
Practical Creativity
Hermit alone in thoughts,
Pure theory
Extrovert Too many attractions,
Connects rather than creates
Unsatisfied, No one to riff with

This is a gross oversimplification of personality and environments, and the text in the boxes is probably unfair to extroverts, who I am sure have created something in the history of humanity. It does however suggest both the risks of cities on being too stimulative (not enough time for thought), and the country (i.e. the antithesis of the city), which may be insufficiently stimulative and leave too much time for thought and not enough for testing of ideas.

Several really good ideas have come from the country though, and not just agricultural implements. My favorite story is that of Philo Farnsworth, one of the individuals credited with inventing the television. As wikipedia says: "A farm boy, his inspiration for scanning an image as series of lines came from the back-and-forth motion used to plow a field." We would not have had television as soon, or possibly in the same form, but for agricultural plowing strategies.

The key is to ensure the city has quite spaces, and the country has connecting places, both of which societies create, although one can argue whether the quantities and qualities are optimal for various things.

See also my old post: Does creativity whither with age?.

260px Close packed spheres with umbrella light camerea (

NPR says: Don't Believe Facebook; You Only Have 150 Friends and discusses Dunbar's number.

Dunbar says there are some neurological mechanisms in place to help us cope with the ever-growing amount of social connections life seems to require. Humans have the ability, for example, to facially recognize about 1,500 people. Now that would be an impressive number of Facebook friends.

Yet the problem with such a large number of "friends," Dunbar says, is that "relationships involved across very big units then become very casual — and don't have that deep meaning and sense of obligation and reciprocity that you have with your close friends."

One solution to that problem, he adds, can be seen in the modern military. Even as they create "supergroups" — battalions, regiments, divisions — most militaries are nonetheless able to maintain the sense of community felt at the 150-person company level.

"The answer has to come out of that," Dunbar says, "trying to create a greater sense of community.

Wikipedia says of Dunbar's number

Dunbar's number is a theoretical cognitive limit to the number of people with whom one can maintain stable social relationships. These are relationships in which an individual knows who each person is, and how each person relates to every other person. Proponents assert that numbers larger than this generally require more restrictive rules, laws, and enforced norms to maintain a stable, cohesive group. No precise value has been proposed for Dunbar's number. It has been proposed to lie between 100 and 230, with a commonly used value of 150. Dunbar's number states the number of people one knows and keeps social contact with, and it does not include the number of people known personally with a ceased social relationship, a number which might be much higher and likely depends on long-term memory size.

Dunbar's number was first proposed by British anthropologist Robin Dunbar, who theorized that "this limit is a direct function of relative neocortex size, and that this in turn limits group size ... the limit imposed by neocortical processing capacity is simply on the number of individuals with whom a stable inter-personal relationship can be maintained." On the periphery, the number also includes past colleagues such as high school friends with whom a person would want to reacquaint oneself if they met again.[3]

Christopher Allen writes about "The Dunbar Number as a Limit to Group Sizes", and posits various sizes are stable, and others unstable, focusing on online communities.

In 2-dimensions, one penny can be surrounded by exactly 6 pennies (of equal size) that it touches. A group of eight pennies will not be as stable as a group of seven (six plus one), since the eighth orbits the close packing of pennies. However if you can fill the second ring, then you can add 12 more pennies (for a total of 19).

Closest packing of circles, spheres, cubes, pyramids, etc, provides a certain number of linkages at degree 0, another number at degree 1, and so on. This is like the valence number of electrons around the nucleus of an atom. Some numbers are stable, others are + or - and less stable.

Does the Dunbar number correspond to any particular physical shape that is stable around 150, but falls apart if larger? This might help explain the limits and network topology of our neurology.

Recently published: Tilahun, Nebiyou and David Levinson (2011) Work and Home Location: Possible Role of Social Networks. Transportation Research part A 45(40) pp. 323-331 [doi]
Abstract: This research explores to what extent people’s work locations are similar to that of those who live around them. Using the Longitudinal Economic and Household Dynamics data set and the US census for the Twin Cities (Minneapolis-St. Paul) metropolitan area, we investigate the home and work locations of different census block residents. Our aim is to investigate if people who live close to one another, also work close to one another to a degree beyond what would be expected at random. We find a significantly non-random correlation between joint home and joint work locations. Further, we show what features of particular neighborhoods are associated with comparatively higher incidences of people sharing work locations. One reason for such an outcome can be the role neighborhood level social networks play in locating jobs; or conversely work place social networks play in choosing the home location or both. Such findings should be used to refine work trip distribution models that otherwise depend mainly on impedance between the origin and destination
I should note, this whole issue of Transportation Research is about social networks and travel, and quite interesting.

Waze is a mobile smart-phone application that lets you see real-time traffic information from other Waze users, and share it. Basically, it uses your smart-phone as a probe. It also lets you update the network (of course if the network is still incomplete, real-time traffic data is almost assuredly sparse). This really depends on critical mass, as I described in this paper:

And lagged information may in some instances be worse than no (or historical average) information.

INRIX National Traffic Scorecard

According to the INRIX National Traffic Scorecard, Minneapolis is the 10th most congested Metro area (for 2008, up 3 from 13 in 2007) in the US. This surprises me, as it is more congested than Atlanta, Phoenix, and Miami, (among others) which all seem worse. These numbers, compiled through GPS logs, compare with the TTI Urban Mobility Indicators, which places Minneapolis at 19 (for 2007), using data from loop detectors.

More interesting is that congestion is down ~ 20%, significantly more than VMT (which is not surprising, since we normally operate at the edge of congestion, and a drop in traffic in congested periods has a significant effect on reducing queue lengths ... no queue, no congestion.

Quotes I like

Two quotes from Here Comes Everybody by Clay Shirky

"Anyone who predicts the death of cities has already met their spouse". (p. 195)

"In a pedestrian setting, running into someone is a good thing; in a car, not so much" (p.201).

Mystery transportation blog

Mystery transportation blog: Transportation Research 101

I have a theory, but I hope the author still gets promoted, so I won't reveal his or her name publicly.


I will be attending the MeshForum conference in San Francisco May 7th and 8th.

This will be an interesting combination of random people from social networking, futurists, and Web 2.0, and me, apparently representing physical networks. I will be talking about the evolution of transportation networks. The conference also has a wiki. The conference is organized by Shannon Clark of JigZaw.

I saw a reference on a social networks message board, which is how I found out about it, and then saw that Professor Anna Nagurney carried the flag for transportation networks last year. Her talk is available at IT Conversations.

David Levinson

Network Reliability in Practice

Evolving Transportation Networks

Place and Plexus

The Transportation Experience

Access to Destinations

Assessing the Benefits and Costs of Intelligent Transportation Systems

Financing Transportation Networks

View David Levinson's profile on LinkedIn

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