Structural estimation of congestion costs

We estimate a structural model of congestion costs using a Bayesian Nash equilibrium approach: The individual's preference for traveling depends on the anticipated level of congestion, which in turn is determined by travelers’ decisions of mobility. The model is estimated using a French transportation household survey. Results confirm the presence of incomplete information and show that aversion to congestion is 6.6% lower during peak times than during off-peak times. A traveler's willingness-to-pay to save 1 min in traffic is estimated at 0.73 euros during peak times and 0.25 euros during off-peak times.     

Pipeline congestion and basis differentials

In the U.S., natural gas pipeline transport has undergone a wave of deregulatory actions over the past several decades. The underlying motive has been the presumption that removing regulatory frictions would facilitate spot price arbitrage, helping to integrate prices across geographic locations and improve efficiency. Yet certain frictions, specifically the effect of congestion on transportation costs, inhibit positive deregulatory impacts on efficiency. With the increase in domestic production and consumption of natural gas over the coming decades, upward pressure on the demand for transport will likely result in an increased occurrence of persistently congested pipeline routes. In this paper we explore the relationship between congestion and spot prices using a simple network model, paying particular attention to the influence of storage. We find that as congestion between two hubs increases, the scarcity value of transmission capacity rises, driving a wedge between spot prices. We empirically quantify this effect over a specific pipeline route in the Rocky Mountain region that closely resembles our structural design. Although our results paint a stark picture of the impact that congestion can have on efficiency, we also find evidence that the availability of storage mitigates the price effects of congestion through the intertemporal substitution of transmission services.     

Greediness and equilibrium in congestion games

We study the class of congestion games for which the set of Nash equilibrium is equivalent to the set of strategy profiles played by greedy myopic players. We show these two coincide iff such games are played over extension-parallel graphs.     

Weighted congestion games with separable preferences

Players in a congestion game may differ from one another in their intrinsic preferences (e.g., the benefit they get from using a specific resource), their contribution to congestion, or both. In many cases of interest, intrinsic preferences and the negative effect of congestion are (additively or multiplicatively) separable. This paper considers the implications of separability for the existence of pure-strategy Nash equilibrium and the prospects of spontaneous convergence to equilibrium. It is shown that these properties may or may not be guaranteed, depending on the exact nature of player heterogeneity.     

Social optimality and cooperation in nonatomic congestion games

Congestion externalities may result in nonoptimal equilibria. For these to occur, it suffices that facilities differ in their fixed utilities or costs. As this paper shows, the only case in which equilibria are always socially optimal, regardless of the fixed components, in that in which the costs increase logarithmically with the size of the set of users. Therefore, achieving a socially optimal choice of facilities generally requires some form of external intervention or cooperation. For heterogeneous populations (in which the fixed utilities or costs vary across users as well as across facilities), this raises the question of utility or cost sharing. The sharing rule proposed in this paper is the Harsanyi transferable-utility value of the game—which is based on the users’ marginal contributions to the bargaining power of coalitions.     

Traffic congestion: an experimental study of the Downs-Thomson paradox

This study considers a model of road congestion with average cost pricing. Subjects must choose between two routes—Road and Metro. The travel cost on the road is increasing in the number of commuters who choose this route, while the travel cost on the metro is decreasing in the number of its users. We examine how changes to the road capacity, the number of commuters, and the metro pricing scheme influence the commuters’ route-choice behavior. According to the Downs-Thomson paradox, improved road capacity increases travel times along both routes because it attracts more users to the road and away from the metro, thereby worsening both services. A change in route design generates two Nash equilibria; and the resulting coordination problem is amplified even further when the number of commuters is large. We find that, similar to other binary choice experiments with congestion effects, aggregate traffic flows are close to the equilibrium levels, but systematic individual differences persist over time.     

Price vs. quantity-based approaches to airport congestion management

This paper analyzes price and quantity-based approaches to management of airport congestion, using a model where airlines are asymmetric and internalize congestion. Under these circumstances, optimal congestion tolls are differentiated across carriers, and a uniformity requirement on airport charges (as occurs when slots are sold or tolls are uniform) distorts carrier flight choices. Flight volumes tend to be too low for large carriers and too high for small carriers. But quantity-based regimes, where the airport authority allocates a fixed number of slots via free distribution or an auction, lead carriers to treat total flight volume (and thus congestion) as fixed, and this difference generates an efficient outcome as long as the number of slots is optimally chosen.     

Optimum city size: A minimum congestion cost approach

The optimal allocation of urban land between the generation of traffic and the carrying of traffic which minimizes congestion costs is derived for a circular city. Unlike previous work which dealt only with the suburbs, this paper deals with both the suburbs and the central business district. This wider view of the problem leads to different conclusions, the most important of which is the fact that at no point in the city is all the land used for transportation. Existence of a maximum size for a city of a given working population, which is independent of relative land and congestion costs, is also discussed with special reference to the case where there is no land rent.     

Survival,reproduction and congestion: the spaceship problem re-examined

This paper re-examines the spaceship problem, i.e. the design of the optimal population under a fixed living space, by focusing on the dilemma between adding new beings and extending the life of existing beings. For that purpose, we characterize, under time-additive individual welfare depending negatively on population density, the preference ordering of a utilitarian social planner over lifetime-equal histories, i.e. histories with demographic conditions yielding an equal finite number of life-periods (imposed by resources constraints). The analysis of the spaceship problem contradicts widespread beliefs about the populationism of Classical Utilitarianism and the antipopulationism of Average Utilitarianism. We also study the invariance property exhibited by various utilitarian rankings to the total space available and to individual preferences. Finally, we compare histories for a spaceship with a stationary population, and try to accomodate intuitions about posterity and renewal of populations.     

Optimal pricing of a two-sided monopoly platform with a one-sided congestion effect

This paper studies the optimal pricing of a two-sided monopoly platform when one side is affected by congestion. We show that the divide-and-conquer pricing strategy (or skewed pricing) depends not only on the relative magnitude of the sides’ price elasticities of demand but it also depends on the marginal congestion cost that an agent imposes on the others. Compared with the no-congestion case, this pricing strategy gives rise to some interesting features that violate the results of Rochet and Tirole (J Eur Econ Assoc 1:990–1029 in 2003, Rand J Econ 37:645–667 in 2006). In the case of equal price elasticities of demand, the no-congested side is charged the highest price. On the other hand, in the case of different price elasticities, the platform congestion pricing depends on a certain threshold of the marginal congestion cost. We show, under some conditions, that the divide-and-conquer pricing strategy is reversed. In the social context, the Rochet and Tirole’s (J Eur Econ Assoc 1:990–1029 in 2003) cost allocation condition is modified by the congestion cost. We show that the congestion does not only affect the buyers’ contribution to the sellers’ surplus, but it also affects the sellers’ contribution to the buyers’.     

HIV病毒检测服务利用中的感知风险问题

对于HIV检测的服务利用,目标人群会主观上感知到许多风险,这些风险是阻碍服务利用的重要因素。本文基于消费行为理论和感知风险理论,对HIV检测中感知风险的产生、发展和内容进行深入分析和理解,从而为改善HIV检测服务、促进服务利用提供参考和建议。     

A geometric approach to the price of anarchy in nonatomic congestion games

We present a short, geometric proof for the price-of-anarchy results that have recently been established in a series of papers on selfish routing in multicommodity flow networks and on nonatomic congestion games. This novel proof also facilitates two new types of theoretical results: On the one hand, we give pseudo-approximation results that depend on the class of allowable cost functions. On the other hand, we derive stronger bounds on the inefficiency of equilibria for situations in which the equilibrium costs are within reasonable limits of the fixed costs. These tighter bounds help to explain empirical observations in vehicular traffic networks. Our analysis holds in the more general context of nonatomic congestion games, which provide the framework in which we describe this work.     

Pricing urban congestion: A structural random utility model with traffic anticipation

We design and estimate a game theoretic congestion pricing mechanism in which the regulator aims at reducing urban traffic congestion by price discriminating travelers according to their value of time (VOT). Travelers' preferences depend on their observable characteristics, on the endogenous amount of congestion anticipated, on their marginal utility (MU) of income and on some unobserved factors. Using a French household survey, we estimate the demand models to simulate different pricing mechanisms. We find that unobserved determinants of transportation demand are significant and are used to measure the anticipated time spent in traffic and the comfort of traveling: diverging from these expectations is felt as more discomfort than if no expectations were formed a priori. However, some of this discomfort is derived from travelers' marginal utility of income: the lost time in traffic is clearly “unpleasant” because of its opportunity cost. When the regulator and the transportation provider share common objectives, we show that a great welfare improvement can be achieved when implementing a homogenous pricing that accurately accounts for travelers VOT.     

Ambiguity and perceived coordination in a global game

In a global game, larger ambiguity is shown to decrease the amount of coordination each player perceives. Consequently, small uncertainty tends to select the Pareto dominated equilibrium of the game without uncertainty. Implications for models of financial crises are drawn.     

Analyzing perceived hunger across states in the US

This paper focuses on the problem of analyzing how factors impact hunger across states when hunger is ill-defined. Hunger (which is a latent variable) is presumed to depend on macroeconomic, legislation, policy, and demographic variables. Based on the Bayesian method of a posterior odds ratios, we find that the high school graduation rate appears to be the single most important factor we identify which affects the perceived hunger measure. First version received: December 1996/final version received: September 1998     

Group identification

I study a model of group identification in which individuals' opinions as to the membership of a group are aggregated to form a list of group members. Potential aggregation rules are studied through the axiomatic approach. I introduce two axioms, meet separability and join separability, each of which requires the list of members generated by the aggregation rule to be independent of whether the question of membership in a group is separated into questions of membership in two other groups. I use these axioms to characterize a class of one-vote rules, in which one opinion determines whether an individual is considered to be a member of a group. I then show that the only anonymous one-vote rule is self-identification, in which each individual determines for himself whether he is a member of the group.