5. EXAMPLE SOURCE CASE

The illustration to be used below to demonstrate some of the ways to utilize COMPASS has to do with efforts to reduce center city traffic snarls through a congestion pricing (CP) project. Basically this would involve designating a circumferential cordon line around the congested area; then identifying the vehicles that cross the line (say with television cameras); and subsequently billing their owners an extra charge for the privilege of driving through the area.  The systems in Singapore and London probably are the most well known (for more information see http://en.wikipedia.org/wiki/Congestion_pricing).

The example case used here deals more specifically with a hypothetical but possibly important situation in which a CP project manager is asked to explore the privacy and general security aspects of the project as well as to provide strategies to alleviate the major issues that may arise. The example will be referred to as the “Transport-Privacy” (TP) case.

While hypothetical, the illustration is based on aspects of several real world examples, in particular the planning for CP projects in Korea and a research project at Virginia Tech exploring the privacy aspects of transportation safety technology.

The illustrative COMPASS source case is a relatively simple one dealing with 14 variables and 20 relationships. A "causal" diagram showing these can be found in CPP Page2. The three variables on the top line to the left are possible strategies; the one in blue is a possible external force; those in red are possible goal-related or “bottom line” impacts; those in white are possible intermediate impacts. The brackets on the links are there in the event that some specification is made of signs and reaction times of the corresponding relations (none have been made so far).

An example of a set of causal connections starts with the (possibly strategic) variable (TV-ANPR) “CCTV Automatic Number Plate Recognition” (that is, using closed circuit TV to record the license plates of vehicles driving through the CP area). This technological strategy is seen as possibly inducing some unscrupulous people to clone legal users’ license plates (variable identification code “LPCLONE”), which action is seen as creating “Privacy Violations” for the real owners (PRIVVIO). Moreover, if there is a national security problem (external force, NATSECP), this also may flow down to have an impact on “Privacy Violations”.

The main items that are not shown on the diagram but frequently are important to the case are the various descriptions of characteristics of the variables and the relationships in addition to a classification of the variables into one or more standard categories (an “ontology”). Included in the first item may be an expanded description of the variable: examples; references; and characteristics like validity and data availability. Included in the second item may be the same characteristics plus, possibly, signs; strengths; time delays; goodness-of-fit statistics; and even arguments as to why the relationship exists at all.

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