working paper

Population Uncertainty and the Timing of an Urban Transportation Infrastructure Investment

Abstract

This paper analyzes the impacts of stochastic population changes on the timing of an investment that reduces congestion in an open, monocentric city with fixed boundaries. Congestion pricing cannot be implemented, but a welfare-maximizing planner can buy land and build transportation infrastructure. Under certainty, I derive a rule of thumb to evaluate infrastructure investments that corrects a standard benefit-cost analysis. Under uncertainty, I show that relying on a standard benefit-cost ratio could lead to investing in bad projects, or investing prematurely, or ignoring attractive projects because of population barriers and the impacts of the congestion externality on the land market.

book/book chapter

Urban Transportation

Publication Date

December 31, 2005

Author(s)

Abstract

The defining trait of urban areas is density: of people, activities, and structures. The defining trait of urban transportation is the ability to cope with this density while moving people and goods. Density creates challenges for urban transportation because of crowding and the expense of providing infrastructure in built-up areas. It also creates certain advantages because of economies of scale: some transportation activities are cheaper when carried out in large volumes. These characteristics mean that two of the most important phenomena in urban transportation are traffic congestion and mass transit.

working paper

Land Use Influences on Trip Chaining in Portland, Oregon

Publication Date

December 31, 2005

Abstract

This paper examines the nature of land use based substitution effects on travel modes, identified by Greenwald, examining the direct impact of land uses inducing trip-making behaviors. These impacts are analyzed in the context of trip chaining, defined here as consolidating two or more non-home activities in a single departure from home. The findings suggest rather than strictly promoting one type of transportation over another, the regional impact of localized urban design practices is to consolidate trip making behavior closer to the home. As such, urban design “carrots” must be complemented with policy “sticks” in order to promote true exchanges of travel modes.

working paper

Strategic Freight Transportation Contract Procurement

Publication Date

December 31, 2005

Author(s)

Abstract

Auction based market clearing mechanisms are widely accepted for conducting business-to-business transactions. This dissertation focuses on the development of auction mechanism decision tools for freight transportation contract procurement. The dissertation categorizes the problems in freight procurement auctions arising in both sport markets and long term markets. Spot markets are widely employed over the Internet using standard classic auctions. For long-term markets, large shippers (typically manufacturing companies or retailers) have begun to use combinatorial auctions to procure services from trucking companies and logistics services providers. Combinatorial auctions involve very difficult optimization problems both for shippers and carriers. In the US truckload market few carriers have the technical sophistication to develop bids for combinatorial auctions. To address the problem we look at a different auction scheme termed a unit auction, where the shipper can exploit the economies of scope in the network and give the carriers the chance to bid on pre-defined packages similar to ‘lotting’ in supply chain procurement.

The problems in developing contract allocations, called the winner determination problem, are computationally complex and large-scale. Hence the development of good heuristics is of utmost importance. Shippers have non-price business constraints, which must be included in the winner determination problems to closely match shipper business objectives. We develop winner determination problem formulations incorporating the non-price business constraints and develop Lagrangian based optimization methods and greedy approximation algorithms for both unit auctions and combinatorial auctions. Extensive empirical results are provided to test the performance of the heuristics against a standard integer-programming solver.

Bidding in auctions from the carrier’s perspective is complicated as it involves taking into account the competitive behavior of other carriers and a carrier’s difficult network optimization problems. We develop bidding strategies for carriers in spot markets using concepts from economic auction theory. For long-term market bidding, we study the effects of demand uncertainty, competitive behavior, carrier network synergies and strategic pricing, and shipper’s winner determination problems on carrier bidding using optimization-based simulation analysis.

working paper

A Tool for the Incorporation of Non-Recurrent Congestion Costs of Freeway Accidents in Performance Management

Abstract

In this research, we develop and apply an analytic procedure that estimates the amount of traffic congestion (vehicle hours of delay) that is caused by different types of accidents that occur on urban freeways in California. A key feature of this research is the development of a method to separate the non-recurrent delay from any recurrent delay that is present on the road at the time and place of a reported accident, in order to estimate the contribution of non-recurrent delay caused by the specific accident. Our analysis involves a case study of accidents that occurred on freeways in Orange County in 2001. The non-recurrent delay caused by the case study accidents is estimated based on inferred link speeds derived from loop data and a binary integer programming formulation to identify the temporal and spatial region affected by the accident. Computations of non-recurrent delay were successfully performed for 870 accidents that occurred on weekdays throughout the period of March through December 2001 on the six major Orange County non-toll freeways. A statistical model was estimated that describes non-recurrent delay as a function of day of week, time of day, weather, and the observable (e.g., from emergency calls and/or aerial or on-scene observation) characteristics of the accident.

working paper

Prices, capacities and service quality in a congestible Bertrand duopoly

Publication Date

August 31, 2005

Author(s)

Abstract

We study the duopolistic interaction between congestible facilities that supply perfect substitutes. Firms are assumed to make sequential decisions on capacities and prices. Since the outcomes directly affect consumers’ time cost of accessing or using a facility, the capacity sharing rule is endogenous. We study this two-stage game for different firm objectives and compare the duopoly outcomes with those under monopoly and at the social optimum. Our findings include the following. First, for profit maximizing firms both capacity provision and service quality, defined as the inverse of time costs of using the facility, are distorted under duopoly: they are below the socially optimal levels. This contrasts with the monopoly outcome, where pricing and capacity provision are such that the monopolist does provide the socially optimal level of service quality. Second, duopoly prices are lower than monopoly prices, but higher than in the social optimum. Hence, while price competition between duopolists yields benefits for consumer, capacity competition is harmful. Third, price-capacity competition implies that higher capacity costs may lead to higher profits for both facilities. Finally, if firms also care about output, this mainly affects pricing behavior; strategic interaction in capacities are much less affected. If duopolists attach a higher weight to output and a correspondingly lower weight to profits, this leads to a deterioration of the quality of service.

working paper

Duopoly Prices Under Congested Access

Publication Date

August 31, 2005

Author(s)

Abstract

Consider two firms, at different locations, supplying a homogenous good at constant marginal production cost. Consumers incur travel costs to the firm for each unit purchased, and the travel costs increase with the amount of travel to each firm (congestion). When all traffic and all congestion are generated by travel to a duopolist, both the Nash-Bertrand equilibrium prices and the Nash-Cournot equilibrium prices exceed the sum of the marginal production cost and the marginal external travel cost. However, when the road is shared by travelers to the duopolists’ facilities and travelers in competitive markets, the Nash-Bertrand duopoly price equals the competitive price and the Nash-Cournot price contains a markup.