Getting to work on time : a proposed time-equitable tolling scheme

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Helsel, John Walter

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Dynamic tolls present an opportunity for municipalities to eliminate congested roadways and fund infrastructure. Known variously as congestion pricing or value pricing and implemented through dynamically priced toll lanes and cordon charges, planners have tried to create free flowing conditions by charging higher prices for travelers who wish to travel in the middle of the peak period. Because these tolls vary in response to demand, travelers are forced to more explicitly consider the cost of travel and so may choose to forgo it entirely or to shift the time of travel for trips that are less important. The imposition of tolls that regulate travel along a public highway through the use of a monetary fee raises worries of inequity. This thesis is thematically divided into two projects. The first is a qualitative investigation into equity. The objective of this discussion is to provide a framework for why we value equity in order to explain whether new policies (without established legal guidance) are inequitable. This explicitly normative discussion draws on work by the philosopher John Rawls to argue that equity concerns in transportation are primarily rooted in a desire to respect all travelers equally and that time poverty ought to be considered in policy-making in the same ways that income poverty already is. I then argue that tolling schemes (by which I mean any structured description of a time-varying toll) that produce time-poverty among poorer travelers ought to be examined as a potential equity concern. The second project is the application of the qualitative equity investigation to a particular implementation of a time-varying toll in the Vickrey bottleneck model to examine whether it raises equity concerns. To achieve this end, I selected an analytically tractable example of the Vickrey bottleneck that eliminates congestion through targeting each traveler’s value of time. I compare and contrast the cost burdens of a no-toll, system optimal toll, and what I will call a “time-equitable” toll on homogeneous and heterogeneous traveler groups. I will show that the time-equitable toll is able to eliminate congestion while creating equitable travel patterns amongst traveler groups.


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