Police shootings are a transport matter

We awake this morning to yet another police shooting, this in Falcon Heights, where a City of St. Anthony police officer shot Philando Castile following a traffic stop. I’ve been past the site, next to the state fairgrounds, hundreds of times. It is not a problematic area or dangerous neighborhood.

This is not the first police shooting.  It is not likely to be the last.

Recent shootings are catalogued at The Counted by The Guardian. In 2016 there are 561 killed by the police. We have no good data from more than a few years ago.  Many begin with traffic stops and moving vehicle violations of one form or another. In this case, Castile was driving and pulled over for a broken light.

Cars (and their drivers) kill 30000-40000 people a year in the US (and are way up this past year) and 1.25 Million globally. This is terrible. It is the highest rate among high-income countries. It justifies many things, including engineering safer roads, educating better drivers at the training stage, designing better vehicles and especially driverless cars, ongoing education programs, reduction in drunk driving, and yes enforcement.

But does that enforcement, which should be aimed at making our roads safer, require armed police officers pulling over men of color at a disproportionate rate because one tail light is out, and shooting them? Is this “enforcement” really about traffic safety? Or rather, is this just another way for municipalities to raise money in fines for minor violations, as was done in Ferguson, Missouri, or discourage people “who don’t belong” from traveling on the quiet streets of someone else’s neighborhood.

Looking at The Counted, by my count the following were transport related …

  • July (to date) – 16 people killed by police in the US.  4 involved driving as precipitating factor (Castile, Small, Saavedra-Vargas, Villanueva)
  • June – 95 people killed by police in the US. 32 transport related (Vierra, Hutson, Guardiola, Noble, Chavez-Angles, Anderson, Rogers, Splunge, Core, Lesko, Howard, Hennessey, Makarenko, Shumpert, Delfino, Damon, Rosser, Pointer, Rodriguez, Moore, Williams, Witherspoon, Bursey, Hollis, Sites, Villagomez, Henson, Moran, Shaham, Smith, Johnson, Pigg)
  • I don’t want to go on.


Certainly most of the killed were violent, and committing  serious traffic violations, or otherwise engaged in illegal activities or fleeing the scene of a crime. Perhaps killing them was the only way to subdue them and keep them from immediately harming others (though other countries don’t seem to have this problem in such numbers, why is that?). And certainly, poorly trained police in the heat of the moment afraid of people who look different and armed with deadly force will sometimes make mistakes that they regret. But why are they in that situation to begin with. Why are they poorly trained? Why are they afraid of the other? Why are they using a gun on someone pulled over for a broken tail light rather than backing off a bit, recording the license plate, calling for help and trying to safely get control of the situation?

There is a cycle of violence. People who believe they will be killed by the police, or even jailed for a long period, have little reason to peacefully cooperate. If they think they can get the upper hand, they will be violent. To date in 2016, 53 police have died in line of duty. Police too have reason to be on a hairspring trigger. They believe they should have a “monopoly on the use of force”.  Police and those they are trying to arrest are in a classic prisoner’s dilemma described by game theory, each fearing for their lives are in the equilibrium where it is better to be the one who shoots first rather than the one who is dead. Police know the vast majority of police who do fire first are cleared.

Philando Castile lost a game he probably didn’t realize he was playing. He never should have been shot. There probably was a better way to tell him his tail light was broken then pulling him over and killing him. There probably were better things for the St. Anthony Police to be doing, that would actually save rather than cost lives.



Contacts and Meetings: Location, Duration and Distance Traveled

Recently published:


• We study attributes that affect location, duration and travel for social activities.
• We find network variables influence meeting location, duration and distance.
• Meeting durations with the close contacts are on average almost 45 minutes longer.
• Respondents travel average 1.5 miles further for meetings with close contacts.
• Individuals are willing to travel longer for longer duration meetings.


The study of travel for social activities presents layered challenges because of the temporal and spatial flexibility with which such activities can be undertaken and the changing set of decision makers involved in each activity episode. This paper seeks to answer a set of questions based on empirical data about how relationship, social network variables, purpose, personal and household constraints, location attributes, and interdependence between meeting duration, distance, and other meetings provide some structure to the observed social activity location and duration decisions. In particular, we investigate what attributes determine whether a meeting takes place in or out of home, and what explains the distance travelled and the duration of meetings. Empirically we show that in-home meetings tend to occur most often with close contacts and less often with distant contacts. When looking at duration and distance travelled, we find that relationship related variables have some of the largest impacts on the distance travelled and the duration of meetings as compared to other variables. We find that meeting durations with close contacts are on average almost 45 min longer, and that respondents are willing to hold these meetings about 1.5 miles (2.4 km) further away from their residences than they would with non-close contacts. Overall the paper illustrates that relationship type, as well as other meeting specific and demographic variables are important in explaining the location, duration and distance travelled for social meetings.

Transportation on Tap: Transit and the Driverless Future

Transportation on Tap:
Transit and the Driverless Future
— A TLC Happy Hour Event 

Tuesday, July 12, 5-7 PM
Republic, 221 Cedar Ave S, Minneapolis

TLC’s 2016 Transportation on Tap happy hour event series is back on Tuesday, July 12! We invite you to Republic to enjoy light appetizers on us and to talk bike, walk, bus, and rail with other TLC members and friends.

Driverless. Self-driving. Autonomous. Robotic. There’s been lots of buzz lately about the coming of vehicles without human drivers. The focus of this Transportation on Tap is how these vehicles interact with transit—buses and trains that carry a lot of people at once.

Would driverless cars replace transit or make it easier to get to buses or trains? Could they be the mobility answer for people unable to drive? What about the design of the vehicles and standards for using them? How would we make sure everyone had access? And, even with driverless cars wouldn’t there still be congestion (and pollution)?
Bring your questions for another lively happy-hour conversation with this month’s featured panel, including:

  • Leili Fatehi, Owner/Principal, Apparatus, and Deputy Director, Self-Driving MN
  • John Levin, Director, Strategic Initiatives, Metro Transit
  • David Levinson, Managing Director, University of Minnesota Accessibility Observatory; Director, Networks, Economics, and Urban Systems (NEXUS) research group

We hope to see you on July 12! All are welcome, but RSVPsare always appreciated. 

Get There

Our event location is conveniently served by the METRO Green Line (West Bank Station) and many Metro Transit bus routes. Bike parking is available near the front entrance. You can find a Nice Ride bike-sharing station right across the street at Washington & Cedar.

There Are Better Ways to Kill Traffic Than Lying to Waze | Wired


Aarian Marshall in Wired writes: “There Are Better Ways to Kill Traffic Than Lying to Waze“, probably inspired by my Tweet:

Speed bump sign
Speed bump sign



I gave a quote for the article and led him to some contacts. My quote


Burn It All Down

The other option is ugly. It’s brutal. Don’t do it, probably. But the absolute best way to reduce cut-through traffic is to transform your neighborhood into a grid. Cut-through traffic “is particularly a problem in areas that try to concentrate traffic onto a few major roads, but leave only a few other routes besides main arterials connected,” says David Levinson, a civil engineer with the University of Minnesota. Streets arranged as connected grids, on the other hand, “tend to distribute traffic more evenly.” That means that even if your neighborhood’s fave arterial road gets shuttered, vehicles fleeing congestion will spread out across the area. No one road will bear the brunt of the nuttiness.

Tragically, there are no shortcuts to beating residential traffic. Instead of using your phone to sabotage Waze, try using it to call your local transportation commissioner.

Dealing with Mess

Every profession deals with a certain type of mess. Doctors deal with the sick and injured, which creates an obvious type of messiness involving various bodily fluids. Sanitation workers deal with another obvious mess. Day care workers deal with the messiness of the pre-school child (both literally and figuratively). Civil engineers deal with messiness of transforming nature into civilization, transforming Rome from a city of mud to a city of marble as Marcus Agrippa did.  The chef deals with the messiness of transforming raw food into something to be eaten while the busboy cleans up the mess of the finished meal. Even accountants deal with the messiness of bureaucratic monetary shell games and the tax code, often dealing with paper receipts and ordering that into systematic data.

A few of us have the luxury of the ivory tower. Our messes are more abstract: turning the jumbled observable facts of the world into coherent theory, turning the jumbled and distracted minds of 19 year olds into ordered thinkers. But we still deal with chaos. Professors are still occasionally killed in the process.

The beauty of the market economy is that people have specialized jobs, so specialized that they can abstract almost everything that is not their job into a comparatively seamless service.

Garden Streets

One of the most influential planning ideas to emerge from the late 19th century was that of the Garden City. Ebenezer Howard, in his book Garden Cities of To-Morrow proposed constructing these new towns in the outer orbit of metropolitan London. The aim was to fuse the best of the city and the country.  Several were realized, including Letchworth (pictures 1 and 2) and  Welwyn Garden City, (pictures) which I had the opportunity to visit in 2006/07. The idea became a foundation for many subsequent new town plans in the UK and influence places in the US like Columbia, Maryland. It today can be seen in a way as a ante-cedent to the New Urbanist movement. Places like Kentlands in Maryland are not complete Garden Cities, but certainly share many elements.

Howard’s Three Magnets

The idea was carried forward into Garden Suburbs, smaller units that were not as economically independent. Hampstead Garden Suburb (picture) is the original example of this development. It is lovely, and very expensive.

The phrase Garden Streets occurred to me at some point. What would this mean? In one sense, we can think of complete streets, that function for all users, not just motor vehicles. These typically have various lanes, for pedestrians, for trees, for drainage, for bicycles, for buses, for cars.  Alternatively it might be a shared street, one where the modes were not channelized, but floated freely amongst each other. But neither of those in themselves really get at the core idea.

The phrase also brings out the idea of formal or naturalistic landscaping, as one envisions from a Boulevard in a neighborhood designed by Frederick Law Olmsted.  In London, the term apparently refers to streets where any unpaved (and some paved) areas are intensively landscaped by neighbors, guerrilla gardeners, as shown in the attached YouTube video.


I think this meaning is closer, but too literal.

Instead, if we bring out the original sense of Garden Cities, we want to fuse the best aspects of town and country. The best country roads, with their naturalistic landscaping are places we want to drive, ride, or walk. The best city streets  with their more intensive use, still create interest if we see places we enjoy walking past because they look, sound, and smell interesting. A Garden Street fuses the best of both creating a street that is desirable to be on, because there is something interesting to see, either nature or an intense and interesting urban environment.

So the Garden Street doesn’t adjoin non-descript blacktop for storing cars, or chain linked fences, or anything that lacks beauty. Instead it aspires to the aphorism that the Journey is the Reward. The Garden Street is not traversed simply to get from here to there, but because it is a preferred place to be, the Garden Street invites you and encourages you to travel on it. It successfully competes with the screen in front of you as place to be.

Some examples are below. Three are shopping streets, two are residential. They are not perfect illustrations (Nara could be lusher), but they are places one wants to be walking in, streets one wants be on, rather than through.

Happy 60th Birthday, Interstate Highway System! You Look Awful | Wired

Aarian Marshall at Wired writes “Happy 60th Birthday, Interstate Highway System! You Look Awful.” The author discusses my work with Matt Kahn:

In 2011, transportation economists Matthew Kahn and David Levinson laid out a kind of radical idea—what if the country stopped focusing on building new highway stuff, and got down to fixing what it already has? In the long run, this would save some serious dough: For every $1 in gas tax revenue spent on your maintenance, the government would save between $4 and $10 on future repairs.

Sometimes a city is a tree

Christopher Alexander wrote a brilliant essay in 1965: “A City is not a Tree“. Long interested in Alexander’s work since graduate school in Berkeley, I recently re-read the piece which has been packaged in a 50th anniversary volume. The original article is available online free. There have been numerous other papers that have commented on various aspects Alexander’s piece, I can’t list them all, it has been cited over 1000 times.

Alexander criticizes new towns, notably my home town, Columbia, Maryland, for being treelike in its conception, rather than what he terms a semi-lattice, but we would more informally call a mesh-like network. The neighborhoods belong to villages, the villages are part of the city. The neighborhoods, following an element of the Radburn plan, are isolated, that is, one cannot go from one neighborhood to another without being on a village street. That’s not to say there is no through traffic, there is, because the neighborhood network has more than one outlet.

But it’s not simply the street network that is tree like, retail is also tree-like. The neighborhood center might have a convenience store (7-11 or Wawa), the village center would have a grocery and 10-20 smaller stores. Town Center had the Mall in Columbia with department stores and over 100 shops. Perhaps Walter Christaller would be proud that Central Place Theory was not merely descriptive, but also prescriptive.

Finally the schools were tree-like. The neighborhood elementary school fed the village-level Middle and High schools.

In practice it was not so tree-like. As a resident of the neighborhood of Bryant Woods in the Village of Wilde Lake, my mom could go shopping at a supermarket at Joseph Square shopping center in the Village of Harper’s Choice. It was only another mile down the road. Later as a resident of Longfellow neighborhood, I could open-enroll into Wilde Lake Middle School. And of course not every neighborhood got an elementary school, not every village got a Middle or High School, and the boundaries were overlapping. So while the stylized schematic drawing may have looked treelike from the perspective of an architect a few thousand miles away, it was not treelike in practice on the ground. See The Next America Revisited for my take.

treenessI don’t believe the planners envisioned it would be so tidy — though better to start out tidy and let entropy emerge rather than start out chaotic and hopes it self-organizes into an aesthetically pleasing environment. Rather my impression from reading a lot of the documents and having lived there and hearing talks from Rouse company officials and so on is that they believed that treelike street networks reduced through traffic, just as planners favor traffic calming today. They believed shopping should be organized into centers, rather than sprawled out uncontrolled along streets, and they should be spaced to be closer to residents. They believed local government is somewhat hierarchical (national, state, county, city) and that village was an organization unit that had some value to regulate things at a more local level than the city (Columbia is not technically a city, it’s just a home owners association, though it is a Census-Defined Place and the second largest in Maryland, after Baltimore, just as was foretold in the 1960s). They believed kids should walk to their neighborhood school, so the neighborhood should be the right size to support the school, which should have X students for pedagogical and cost-efficiency reasons, and ideally students would walk to their middle and high school too, but that middle and high schools should be larger. So the hierarchy was a natural way of organizing that.

But even if Columbia is innocent of being as treelike as Alexander feared (and certainly some new towns were more treelike), the suburbs are certainly more treelike than cities. My students have measured the “treeness” of networks, introducing the metric in Xie and Levinson (2007) Measuring the Structure of Road Networks. For instance in Network structure and the journey to work: An intra-metropolitan analysis (under review) by Pavithra Parthasarathi and myself, we see that treeness is not surprisingly higher at the suburban edges of the metropolitan area than in the center, though it declines as we see rural areas, where the sparser network is also more mesh or grid-like. (See figure)

Still, sometimes the city is a tree, or at least aspects of it are. In particular, many networked physical infrastructures are better organized as trees, especially if they require a large capital investment (like a waste water treatment facility). Similarly, the stream and river valleys are naturally organized as hierarchies. Transit networks are also often more treelike or radial than roads, and while may eventually evolve into ring-radial system, don’t generally start out that way. See Roth et al. 2012.

This transit network looks pretty tree-like.

Clearly social connections should not be assumed to flow in a way that maps directly to the physical layout of the network, all other things being equal, you are more likely to know your neighbor than a randomly selected person farther away. Yet, in a modern world with migration and telecommunication, you are likely to know someone specifically who is not on your block and to not  know everyone on your street. Growing up, my mom’s friends were scattered across Columbia, not just in her neighborhood. ‘Community without propinquity’ was first identified by Berkeley Planner Mel Webber, and certainly applied in Columbia as it does everywhere, where people could meet based on any kind of interest, not simply the desire to live on the same street. The physical form of the city does not represent how the city works, but more importantly the plans do not determine how the city works. People and their relationships are affected by their environment, and reshape it to suit their needs.

Initial impressions of A Line bus mostly positive | Star Tribune


Janet Moore of the Strib writes: “Initial impressions of A Line bus mostly positive.” I get a quote:

University of Minnesota Prof. David Levinson recently released an accessibility evaluation of the A Line, part of a broader, federally funded project. The study found that workers living within a half mile (or a 10-minute walk) of the A Line can reach 11 percent or 4,500 more jobs within 30 minutes of the new service than before. Employers in the same area can reach 6.4 percent more workers, or 2,000 additional employees.

“We found the net accessibility [of the A Line] is positive overall, so more people are winners than losers and the losers don’t lose very much,” Levinson said.

Roth says the A Line appears to be attracting new riders who like the new stations and the light-rail-like amenities over the local bus.

Levinson noted: “You won’t change your behavior on Day One, it takes awhile to build. Over time, we expect people to use the A Line more than the 84. And if more people use it, then it justifies the investment.”

Note the link to our report is added. The Strib surely meant to link back to the original report, but couldn’t because HTML is hard.

(Update: 6/28 Now linked to)