Evaluation in a Time of Uncertainty

2013-09-302013-09-26 | David Levinson

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

2013-09-292019-03-14 | David Levinson

Recent paper:

Asaf Bar-Yosef, Karel Martens, Itzhak Benenson (2013) A model of the vicious cycle of a bus line Transportation Research Part B 54 (2013) 37–50

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

2013-09-272013-09-26 | David Levinson

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’

2013-09-272013-09-27 | David Levinson

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.”