A Review of Game Theory Models of Lane Changing

Recently published:

Driver lane-changing behaviours have a significant impact on the safety and the capacity of the vehicle-based traffic system. Therefore, modeling lane-changing ma- neuvers has become an essential component of driving behaviour analysis. Among microscopic LC models, game theory-based lane-changing models highlight the inter- action of drivers, which reveal a more realistic image of driving behaviours compared to other classic models. However, the potential of game theory to describe the hu- man driver’s lane-changing strategies is currently under-estimated. This paper aims to review the recent development of game-theoretic models that are classified ac- cording to their different methodologies and features. They are designed for both human-driven and autonomous vehicles, and we hope they can find applications in future AV industries.


Access Across America: Auto 2016

My peeps back in Minnesota released Access Across America: Auto 2016. They write:

This study estimates the accessibility to jobs by auto for each of the 11 million U.S. census blocks and analyzes these data in the 50 largest (by population) metropolitan areas.

Travel times are calculated using a detailed road network and speed data that reflect typical conditions for an 8 a.m. Wednesday morning departure. Additionally, the accessibility results for 8 a.m. are compared with accessibility results for 4 a.m. to estimate the impact of road and highway congestion on job accessibility.

Rankings are determined by a weighted average of accessibility, with a higher weight given to closer, easier-to-access jobs. Jobs reachable within 10 minutes are weighted most heavily, and jobs are given decreasing weights as travel time increases up to 60 minutes.

The report presents detailed accessibility and congestion impact values for each metropolitan area as well as block-level maps that illustrate the spatial patterns of accessibility within each area. It also includes a census tract-level map that shows accessibility patterns at a national scale.

Wanting to Drive and Quality of Driving

The Chevy Vega
The Chevy Vega

Our society has undergone many subtle and not-so-subtle changes in the past few decades. Among those related to driving, safety, and perceived safety, I believe there have been lasting effects.

When I was growing up, and I went for a ride with my mom, I would sit in the front seat of the car. I would wear a seatbelt (a habit formed because of the seat-belt ignition interlock on our Chevy Vega preventing the engine from starting without seat belts (a one-year experiment reviled by the driving public). My children sit in the back seat because of the rise of so-called child safety seats and air bags.

When I was growing up, I would walk down the block alone in pre-school and Kindergarten, and around the neighborhood by 1st grade, and all over town by 3rd grade. I would ride the ColumBus by 4th grade with my Package Plan card (giving me free rides in on the system, a benefit which has since been removed). Today there is a movement for Free Range Kids because such freedom has diminished.

Practicing pop sociology, I attribute this decrease in children’s freedom to the Atlanta Child Murders, the Missing Kids on the back of Milk Boxes, Adam Walsh, and Amber Alerts, all which are making child kidnapping seem much more common than it was before or than it really is. Couple this with the decreased number of children per family, meaning children are less disposable than they once were.

Milk Carton Kids
Milk Carton Kids

Today’s kids sit in the back seat, have a much diminished range, are more likely to be driven by parent or school bus to their school.

Drivers from other countries in the US are often derided as poor quality. However, keep in mind, they grew up seldom riding in a car at all if ever, and thus never learned the tacit rules of driving that many Americans are accustomed to. Perhaps the driving tests in the US are insufficiently stringent, but there are many things one can learn about driving just be riding in the front seat of a car, which immigrants, and today’s kids, fail to experience.

VW Drivers Wanted
VW Drivers Wanted

The net is that when you go through life as a passenger rather than a driver, your motivation for driving is lower, since you are not modeling driving yourself as you would watching through the front windshield, and your quality of driving is lower since you lack experience. These two factors presumably feed on each other, as people like doing what they are good at. I posit this as one of a number of factors that has led to a significant decline per capita travel.

The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.
The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.

Reflections on the Streetcar of Portland

A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King
A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King

Riding for a conference from the Portland airport to Portland State University on Light Rail Transit (LRT) and then streetcar gave me time to reflect on the Elysian Fields of transportation engineering, the Nirvana of networks and nexi.

Portland, Oregon is one of the major battlegrounds in the mode wars (car vs. transit and the internecine rail vs. bus). It has since the 1980s been held up by planners as the exemplar American city that does almost everything right. The foremost thing they do right in the view of the planning establishment is promoting LRT and bicycling.

The fascination with rail transit in particular (especially as compared with bus) was something I have never quite grokked. As a rational observer with formal training in transportation, I have had a hard time understanding the emotional relationship people have with rail. Why do people like LRT more than bus? Is it simply how we operate them, or that it is modern capital, or is there a psychological benefit associated with deterministic tracks vs. widely diverging roads? There are lots of theories on the matter, I will identify a few below.

  1. Ride quality. The quality of the ride on an LRT is smoother and less herky-jerky than a bus, and passengers have a nicer facility.
  2. Navigability. It is hard to navigate current US bus systems, while the fewer number of rail lines are fairly easy to figure out. Because trains cannot steer, they cannot get lost the way a bus can.
  3. Speed. Trains are faster than local buses, especially if they have their own right of way and few stations.
  4. Permanence. I can make a permanent investment decision based on the location of rail lines, as the transit system is committed to this line, while a bus line may be temporary.
  5. Nostalgia. People who like LRT recall (or wish they could recall) the immediately post-World War II America when streetcars were at a maximum. 1946 was a magical period in US history, a boom following the long depression, when streetcar networks if not at a maximum were really close. (Coupled with a conspiracy theory about their removal)
  6. Sexuality. This is part of the theory presented by Jonathan Richmond’s in his book Transport of Delight and earlier paper The Mythical Conception of Rail Transit in Los Angeles. The image of the train entering the tunnel clearly evokes a primal response.

There are logical rejoinders for the first four (though not the nostalgia or sexuality argument I suppose), the most obvious is that if you spent the kind of money you are spending on rail on buses instead, and operated them better, buses would be quite nice. Navigability could be improved with a bit of thought (and trains can divert), while permanence of the last generation of streetcars (1887-1954) clearly was temporary.

The theory I have now adopted comes from my recent trip from Minneapolis to Portland accessing the airport at both ends via LRT, and then riding the Portland streetcar almost full circle. Rail transit forms an urban superstructure. Guideway transit, esp. LRT makes the city more like a single structure, and makes everything seem closer. The LRT vehicle is continuously running, and if activities are along the path of the vehicle, everything seems quite coordinated. In a way by organizing activities linearly (or multi-linearly), it simplifies the city. Hopping on a train is much like getting on an elevator.

LRT, like walking indoors, keeps you enveloped within civilization, while walking, biking, or driving is a frontier experience, you alone in the wilderness. (And bus falls in-between). We can posit that distances within buildings seem shorter than distances between buildings (Some literature along the notions of this idea exist, see Tversky, but it is not directly on point). Distances connected by the urban superstructure will likely feel closer than those which are not so connected. Walking through a modern airport, or the Minneapolis Skyway, will tell you enveloped distances can be quite large, but still not feel as large as leaving one building into nature for another.

Preferences for civilization or frontier-crossing (or degree of each) vary across individuals. Driving of course places you in a machine, but you, not civilization, are operating the machine, so just as driving is freedom, not everyone wants that freedom to drive, they may prefer freedom from driving. The extent to which you believe in the importance of community over individuals (or vice versa) will affect your perception of the issue.

( LRT may also be more popular than traditional underground subway (Metro) systems. People of course like being able to walk out the door and step onto a train more than having to descend through the gates of hell, Metro to get to the underground subterranean system. There are many reasons, not least of which is the extra time and energy required to so descend. The advantages in principle are faster point to point travel time, but that depends on the access cost vs. the in-motion speed. )

Transit invokes further passions because of the positive feedback loop between ridership, revenue, and route frequency, especially where transit is weak as in much of the US. My riding transit creates a positive externality for you (more riders, shorter headways, and more routes), so of course if you ride transit, you want to impose your preference on me. It is only selfishly rational. Further cars use scarce roadspace. While similar feedback loops may exist on the highway side (more drivers means more closely spaced roads), congestion mitigates that and the network is largely built out, so drivers do not feel the same need to impose their modal preference on the transit riding minority. Finally, drivers may benefit in the short term if other drivers take transit. (Where transit is already congested and frequent, additional riders produce few positive externalities as diminishing returns set in).