Evaluation in a Time of Uncertainty

I was recently in Copenhagen, where I gave a keynote talk at the UNITE Conference (Uncertainty in Transport Evaluation) at DTU. My thanks to the organizers for inviting me. (I really liked Copenhagen, more on that in a later post).

My talk was titled: Evaluation in a Time of Uncertainty

Abstract: We live in a world where the future is increasingly unpredictable. How should we evaluate transportation investments? Should we even try to evaluate investments in advance? What do we know about what people value? This talk will consider directions in transportation evaluation, and suggestions for better decision-making given uncertainty.

The slide deck is here.

The essential tension in my presentation is the hypothesis that essentially “Long-term forecasting is impossible” vs. my argument that forecasting can only be improved if we “Make forecasters responsible for forecasts.”

A model of the vicious cycle of a bus line

Recent paper:

It has been frequently noted that in a non-regulated environment the development of public transport service is self-adjusting: Faced with decreasing demand, operators will tend to reduce service to cut costs, resulting in a decrease in the level-of-service, which then triggers a further drop in demand. The opposite may also occur: high demand will induce the operator to increase supply, e.g. through an increase in frequency, which results in a higher level-of-service and a subsequent increase in passenger numbers, triggering another round of service improvements. This paper adds to the literature by presenting an analytic model for analyzing these phenomena that we call vicious and virtuous cycles. Based on field data regarding passengers’ variation in willingness-to-wait for a public transport service, we investigate the dynamics of the line service and show how the emergence of a vicious or virtuous cycle depends on the total number of potential passengers, the share of captive riders, and bus capacity. The paper ends with a discussion of the implications of the findings for the planning of public transport services.

This paper extends a pedagogical model we developed in Planning for Place and Plexus and makes it much more rigorous.

Transit Exchange

Usually, when someone spams your comments, you delete it. But I got an interesting spam comment the other day which is a potentially good idea. There is a company called Texxi which is arguing there is a market in which people post where they are going to enable dynamic ride-matching/taxi services, which they call a Transit Exchange.

The message in full

The answer, David, is a Demand Responsive Transit Exchange which borrows heavily from the I.T. network transit exchange (that, incidentally, also allows for largescale peer-peer bandwidth sharing and trading, killing centralised monopolies and NSA snoopers in one go – http://www.educause.edu/members/michael-hrybyk), finance, aeronautics and biology.

RoadSpaceTime is virtualised into a tradable commodity and made available to people via mobile devices (XML, SMPP, SMS, Smartphone App, Web Page or Email) to connect to a futures exchange and “database of transit intentions” which store itineraries and price searches.

A credit contagion solver working through the social network graph applies genetic algorithms to suggest “solutions” to customers in realtime. In 2013, this is now laughably trivial, but even 5 years ago, the cost of the computing power would have required millions in VC money.

Take a look at:

“The Market Opportunity for Dynamic Ridesharing” | http://bit.ly/vtpi-EqTransit-1
Or download (26Mb pdf) The Market Opportunity – http://www.texxi.org/pres/marketopp.pdf

“Transport – A New Beginning” | http://bit.ly/vtpi-EqTransit-3
Or download (21.70Mb pdf) – http://www.texxi.org/pres/newbeginning.pdf

“The underpinnings of the Transit Exchange” | http://bit.ly/tranexch00
Or download (19.53Mb pdf) – http://www.texxi.org/pres/underpinnings.pdf

Certainly they are not the only ones in this space, and the idea has been around for a quite long time (Mel Webber noted the idea of Dynamic Ridesharing decades ago) but they filed for a patent as early as 2006. They propose to be the market maker here, rather than relying on peer-to-peer matching. They thus would guarantee the seller and the buyer that they will be fulfilled at a given price (and get a vig).

They say:

By combining Futures Exchanges + Mobile + Social + Big Data + Genetic Algorithms any vehicle with spare capacity becomes your private vehicle for just when you need it.

Whatever your needs, Texxi can make any participating local vehicle fleet able to offer an easy and tailored transport solution for you
Patent Pending (July 2006)

They also have a really weird video

The website is worth visiting if you are interested in possible future scenarios for The New Mobility.

Why we engage in ‘security theater’

At Symposium Magazine: Why we engage in ‘security theater’ :

“The politics of security are difficult. If you are in favor of security, you must be in favor of more spending on security, or on anything that will “keep us safe.” If politicians or bureaucrats oppose a proposed security measure and something happens, they will be blamed. Security ratchets up quickly. Ratcheting down can only really be by attrition.”

Value of Reliability at Symposium Magazine

I am blogging this week at Symposium Magazine.

Yesterday’s post introduced our Value of Reliability study on the HOT lanes of I-394. Today’s Post reports on the findings.

These extend the post Understanding the Irrational Commuter from earlier this month.

Monday’s post was Understanding trade-offs and public trust.

Wheels on Wheels: An Argument for Universal Design

On a recent LRT trip, on my car, there was a person in a wheelchair, a bicyclist with bicycle, a stroller, and travelers carrying wheeled suitcases. How much of this was made possible by “Universal Design” and the Americans with Disabilities Act?


Universal design is the design of products and environments to be usable by all people, to the greatest extent possible, without the need for adaptation or specialized design. —Ron Mace

The problems that transportation disadvantaged individuals face are similar to, but more severe than the problems that the rest of the population sees on a day-to-day basis. Take, for instance, the simple question of which bus goes from the bus stop nearest my home to downtown. When going to the bus stop, is information provided other than the simple sign saying “Bus Stop”? Many stops don’t even identify routes, much less schedules. Without a guide (either person or documentation), using the system entails taking great risks, among them the risk of winding up across town from your desired destination and being hours late. The relatively simple, but seemingly revolutionary idea of providing information with the service may help. For instance, operators should make the signage clear so the bus stop can be found, make clear the route number, route end points, and the direction toward which the user needs to travel at the bus stop; make clear when the bus is coming, especially when service is infrequent; and clearly convey to the user, when he or she should get off the bus (which may require more than drivers announcing the bus stops as the bus travels the route). While this may be critical for those who are unfamiliar with the location (tourists) or the language (immigrants), it is also important for those who are cognitively challenged, and would probably provide a much better travel experience for those who lack special difficulties. Some transit systems do this, especially in downtown areas. Others would rather spend money on new rail construction (seeking new, wealthier customers) than make the existing bus system (serving existing, poorer customers) work well.

To provide another example, when the Americans with Disabilities Act was passed, a major concern was retrofitting buses with elevators to accommodate wheelchairs. Buses traditionally had steps leading from the ground to the level where passengers sit. A more universal design would lower the floor of the bus (and gradually raise the level of the ground at the bus stop) so that wheelchairs could roll onto the vehicle, the way that occurs on many subway systems. Such a system would benefit many others with poor knees who can walk but find steps difficult. The lowering of the floor of buses is becoming more common, the raising of bus stops less so.

Having a universal design assists those who need the assistance while benefiting others. The principles of universal design are a set of values, but they are hard to disagree with:

  1. Equitable Use: The design is useful and marketable to people with diverse abilities.
  2. Flexibility in Use: The design accommodates a wide range of individual preferences and abilities.
  3. Simple and Intuitive Use: Use of the design is easy to un- derstand, regardless of the user’s experience, knowledge, language skills, or current concentration level.
  4. Perceptible Information: The design communicates neces- sary information effectively to the user regardless of ambient conditions or the user’s sensory abilities.
  5. Tolerance for Error: The design minimizes hazards and the adverse consequences of accidental or unintended actions.
  6. Low Physical Effort: The design can be used efficiently and comfortably and with a minimum of fatigue.
  7. Size and Space for Approach and use: Appropriate size and space is provided for approach, reach, manipulation, and use regardless of user’s body size, posture, and mobility.

Excerpted from The Transportation Experience: Second Edition, by William Garrison and David Levinson. Oxford University Press (2014)