What We Can’t Observe: Accounting for Latency in Joint Models of Activity-Travel and Location Choice Behavior
Ram M. Pendyala

March 12, 2013


Forecasting a region’s travel has long relied on models of human travel behavior capable of representing the interrelationships among a multitude of activity-travel and location choices that people make over time and space. However, an issue that is often overlooked in choice modeling efforts is that key phenomena underlying model specification and estimation are often unobserved. As a result, analysts end up making very significant assumptions regarding underlying choice processes that may not necessarily be reflective of the behavioral heterogeneity present in the sample. Unfortunately, in many modeling contexts, these underlying phenomena are unobserved. This presentation articulated the problem and offered two contexts where the notion of latency was explicitly incorporated into the econometric behavioral model formulation.



The PECAS Model of Atlanta
Dr. John E. Abraham

March 7, 2013

Where:  Instructional Center, Room 109


Abstract: The PECAS Model of Atlanta is a spatial economic forecasting model for the 20 county region.  It forecasts development patterns, home and business locations, economic interactions and economic performance into the future.  It is policy sensitive to transportation infrastructure, transportation services, land use regulations, taxes and environmental policy.  The developer model micro simulates individual construction events on 1.9 million parcels records representing the land in the region using a joint discrete-continuous logit formulation.  The spatial economic module simulates the location choices of businesses and households within the developed land, and their interactions that lead to travel on the road network, using an additive logit formulation.  The simulation is founded on a synergy between spatial economic theory and random utility theory.  The integrated modeling system includes both of these PECAS components, as well as the Atlanta Regional Commission's travel demand model and a spatial economic forecasting model.

The presentation will cover the theory behind the PECAS modeling framework, the development of the PECAS model for Atlanta, the data used in the Atlanta region, the software implementation of the model, and the application of the model for the regional transportation plan.  Examples from other PECAS models (such as San Diego, Baltimore, Sacramento, Oregon etc.) will provide additional context.

Bio: Dr. John E. Abraham is the principal software developer of the PECAS system for integrated land use transportation modeling, and co-author (with Dr. John Douglas Hunt) of the theoretical formulation.  Dr. Abraham has 20 years of experience in developing and calibrating spatial economic and travel demand models. Dr. Abraham has expertise in developing and calibrating models to provide computer simulations that are both accurate and practical for analyzing policy and scenarios. He is an expert on survey techniques for understanding preferences, measuring trade off rates, and predicting behavior. Dr. Abraham can quickly program advanced modeling techniques into software due to his strong mathematical and statistical background and his knowledge of algorithms and data structures. He is an expert software architect with a focus on object-oriented design. John is a principal at HBA Specto Incorporated in Calgary, AB, Canada.

Nash-Stackelberg games in transportation networks: leveraging the power of smartphones for traffic monitoring and management

Dr. Alexandre Bayen



February 19, 2013



The first part of this talk investigates the problem of real-time estimation and control of distributed parameters systems in the context of monitoring traffic with smartphones. The recent explosion of smartphones with internet connectivity, GPS and accelerometers is rapidly increasing sensing capabilities for numerous infrastructure systems. The talk will present theoretical results, algorithms and implementations designed to integrate mobile measurements obtained from smartphones into distributed parameter models of traffic. The models considered include Hamilton-Jacobi equations, first order conservation laws and systems of conservation laws. Other techniques developed will be briefly presented as well, relying on ensemble Kalman filtering.

In the second part of the talk, a game theoretic framework is developed to study Stackelberg routing games on parallel networks with horizontal queues, applicable to transportation networks. First, a new class of latency functions to model congestion with horizontal queues is introduced. Then, for this class of latency, the Stackelberg routing game is studied: assuming that a central authority can incentivize the routes of a subset of the players on a network, and that the remaining players choose their routes selfishly, can one compute an optimal route assignment (optimal Stackelberg strategy) that minimizes the total cost? A simple strategy is proposed, the Non-Compliant First (NCF) strategy, that can be computed in polynomial time. The strategy is showed to be optimal. It is also showed to be robust, in the sense that some perturbations of the NCF strategy are still optimal strategies.

The results will be illustrated using a traffic monitoring system launched jointly by UC Berkeley and Nokia, called Mobile Millennium, which is operational in Northern California and streams more than 60 million data points a day into traffic models. The talk will also present a new program recently launched in California, called the Connected Corridor program, which will prototype and pilot California's next generation traffic management infrastructure.

Federal Transportation Funding:

A Conversation with Joshua Schank

October 18, 2012


This lecture and discussion with Eno Foundation President and CEO Joshua Schank focused on the passage of MAP- 21 and the future of federal transportation legislation. Schank was transportation policy advisor to Sen. Hillary Clinton during the development of the last surface transportation authorization bill (SAFETEA-LU).

Urban Transportation: Developments and Progress toward Livable Cities

Vukan R. Vuchic

April 5, 2012


This seminar offered an overview of several stages of transportation-city relationships, followed by a review of transportation modes and their characteristics. Serious problems of traffic congestion and methods for achieving a balanced transportation system, particularly between private cars and public transportation, were defined. Examples from many world cities offered valuable lessons in successes and mistakes, emphasizing the great need for better understanding of the complex problems of urban transportation.


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