Alternative congestion pricing schedules

It is important that alternative congestion pricing schedules are compared with respect to a broad spectrum of their effects. This paper uses an equilibrium simulation model of peak-period commuting along an urban highway to compare quantitatively both positive and normative effects of six congestion pricing schedules. Three of these schedules have been investigated qualitatively in the literature; the others are new. The results indicate that flat tolls are favored over smoothly varying tolls for revenue generation or increase in vehicle occupancy, but are disfavored for efficiency maximization, increase in consumer surplus, or reduction in congestion delays.     

Road congestion: A reconsideration of pricing theory

In this paper, the effect of congestion tolls upon the pattern of traffic flows is examined. Congestion tolls influence the individual commuter's decision of when to make a trip, inducing him to travel at less congested times. When all commuters are taken together, congestion tolls and the individual consumers' decisions lead to an efficient reorganization of traffic flows relative to a non-toll situation. In fact, for the same total number of commuters, per person costs of travel including the toll may decline with the imposition of tolls and efficient reorganization of traffic flows.     

The incidence of congestion tolls on urban highways

The incidence of an optimal short-run congestion toll is investigated using an equilibrium model of modal choice and congestion on a highway corridor served by express bus transit. It is argued that for an externality tax the usual equi-revenue analysis of burdens is inappropriate; instead, welfare effects are computed under three alternative assumptions about redistribution of toll revenues. In almost all cases the net result is benefits for all income groups. It is concluded that congestion tolls should not be rejected on grounds of income distribution, but that an explicit package of tolls and revenue uses is probably a political prerequisite for adoption.     

Highway congestion and congestion tolls

Highway congestion is ubiquitous. We model the speed-flow relationship, identifying private and social costs, and the implied congestion toll for a number of proposed formulations. Using data for a limited access highway, we estimate these speed-flow relationships and find that flow as a quadratic function of speed fits best. The unit of observation is the individual vehicle and flow is measured in terms of the vehicles which passed a point shortly before or after the reference vehicle. Maximum possible flow occurs at 30–35 mph and the congestion toll is infinite for slower speeds. Rush-hour drivers have greater speeds for a given volume of traffic and thus congestion tolls must vary by time of day.     

A behavioural model of traffic congestion: Endogenizing speed choice, traffic safety and time losses

Conventional economic models of traffic congestion assume that the relation between traffic flow and speed is a technical one. This paper develops a behavioural model of traffic congestion, in which drivers optimize their speeds by trading off time costs, expected accident costs and fuel costs. Since the presence of other drivers affects the latter two cost components and hence the Nash equilibrium speed, a ‘behavioural’ speed-flow relationship results for which external congestion costs include expected accident costs and fuel costs, in addition to the time costs considered in the conventional model. It is demonstrated that the latter in fact even cancel in the calculation of optimal congestion tolls. The overall welfare optimum in our model is found to be off the speed-flow function, and off the average and marginal cost functions derived from it in the conventional approach. This full optimum requires tolls to be either accompanied by speed policies, or to be set as a function of speed. Using an empirically calibrated numerical simulation model, we illustrate these qualitative findings, and attempt to assess their potential empirical relevance.     

Congestion, Land Use, and Job Dispersion: A General Equilibrium Model

In dispersed cities, congestion tolls would drive up central wages and rents and would induce centrally located producers to want to disperse closer to their workers and their customers, paying lower rents and realizing productivity gains from land to labor substitution. But the tolls would also induce residents to want to locate more centrally in order to economize on commuting and shopping travel. In a computable general equilibrium model, we find that the centralizing effect of tolls on residences dominates on the decentralizing effect of tolls on firms, causing the dispersed city to have more centralized job and population densities. Under stylized parameters, we find that efficiency gains from levying congestion tolls on work and shopping travel are 3.0% of average income. About 80% of such gains come from road planning and 20% from tolls.     

A generalized congestion function for highway travel

Urban planners designing the optimal scale and pricing of highway services must pay close attention to the choice of the functional form used to describe the relationship between highway speed and the volume of roadway traffic. This congestion relationship is a crucial empirical fact for planning. While past work have posited a variety of speed-volume models, no successful efforts have been made to statistically compare the different specifications. This paper presents a generalized congestion function (GCF) which allows us to select the preferred (by a maximum likelihood criterion) speed-volume specification. The most prominent previous speed-volume models are all shown to be special cases of GCF. Failure to use the GCF approach may be very costly. For example, in the design of highway tolls the switch from the optimal GCF specification to a statistically “second-best” model may lead to a consumer surplus loss of $1 million annually for a typical urban area.     

Optimum,market and second-best land use patterns in a von Thünen city with congestion

This paper constructs a von Thünen type model with traffic congestion and two production inputs. A comparison between optimum and market land use patterns is presented. The second-best problem in which congestion tolls are not allowed is also considered. The policy variable in the analysis is the allocation of land between production and transportation. The result is examined in a cost-benefit analysis based on market rent.     

Efficient Congestion Tolls in the Presence of Unpriced Congestion: A Peak and Off-Peak Simulation Model

This paper develops a congestion pricing model to examine efficient congestion tolls for an urban highway facility that resembles California State Route 91, the highway that has been subject to congestion tolls since December 27, 1995. Two lanes out of six (each way) are subject to congestion tolls, and the other four lanes are not. The simulation model combines the economic theories of second-best pricing of transportation facilities and peak-load pricing, and considers both welfare-maximizing and profit-maximizing cases. The simulation results show that the second-best peak period toll is quite low and that the welfare gains from the toll are modest compared to a regime in which all lanes are subject to tolls.     

Inside the queue:: hypercongestion and road pricing in a continuous time–continuous place model of traffic congestion

This paper develops a continuous-time–continuous-place dynamic economic model of traffic congestion, based on car-following theory. The model integrates two archetype congestion technologies used in the economics literature: ‘static flow congestion’ and ‘dynamic bottleneck congestion.’ With endogenous departure times and a bottleneck along the route, ‘hypercongestion’ arises as a dynamic equilibrium phenomenon on the upstream road segment. Congestion tolls based on an intuitive dynamic and space-varying generalization of the standard Pigouvian tax rule can hardly be improved upon. A naïve application of a toll schedule based on Vickrey's bottleneck model performs much worse and reduces welfare in the numerical model.     

Clubs in an urban setting

In this paper the properties of a congestable concentrated local public good (CCoLPG) are described, taking into account both locational aspects and congestion. This discussion, therefore, completes the analysis of congestable local public goods (LPG) which was started in our earlier paper (Congestable local public goods in an urban setting, J. Urban Econ., 290–310 (1982). It is here shown that the optimal provision of CCoLPG leads to the creation of clubs, where the government has to determine the location and provide the optimal quantity of LPG in each club and also levy congestion tolls on users according to their level of utilization of the club. Congestion tolls cover the αest part of the costs, where α is the level of congestability of the CCoLPG. The rest of the costs are covered by taxing land rents. Clubs will form, possibly more than one per city, even if the LPG is pure (i.e., α = 0) and they will contain a single household if the LPG is private (i.e., α = 1). The difference between these results and those of classical club theorists stem from the fact that here we also take into account the limited supply of land of given accessibility (i.e., locational aspects), which like congestion lead to the creation of clubs. When these two factors are considered together, it explains why congestion tolls alone are not sufficient to finance clubs' operations, or why pure LPGs also have to be provided locally, etc.     

Weak congestion in output additive data envelopment analysis

Our earlier work [Wei QL, Yan H. Congestion and returns to scale in data envelopment analysis. European Journal of Operational Research 2004;153:641–60] discussed necessary and sufficient conditions for the existence of congestion together with aspects of returns to scale under an output-oriented DEA framework. In line with this work, the current paper investigates the issue of “weak congestion”, wherein congestion occurs when the reduction of selected inputs causes some, rather than all, outputs to increase, without a worsening of others. We define output efficiency for decision making units under a series of typical DEA output additive models. Based on this definition, we offer necessary and sufficient conditions for the existence of weak congestion. Numerical examples are provided for purposes of illustration.     

Second-best policies for congestion externalities

This is the third in a series of three articles on the topic of congestion externalities. We use an urban general-equilibrium model to test the efficiency of several second-best policies for congestion externalities. The most efficient second-best policy is a program of land-use controls; the program generates a welfare gain of $3.38 per household per week. A unit tax on commuting is a less efficient policy, with a welfare gain of $1.15.     

Congestion Caused by Speed Differences

This paper investigates road traffic congestion caused by speed differences using both analytical and numerical simulation models. Especially outside peak hours, speed differences are probably one of the most important reasons for congestion. Some main conclusions are that optimal tolls for slow vehicles are higher than those for fast drivers, that the marginal external costs and the optimal tolls for slow drivers are actually decreasing in the equilibrium number of slow drivers, and that “platooning” may become an attractive option especially when the desire for a low speed is caused by a lower value of time.     

Internalization of congestion at US hub airports

I study delays and congestion patterns in US hub airports during periods of high flight volume. I find that these periods are longer when the share of flights operated by the hub airline is greater, and these longer periods exhibit shorter delays. These results lend support to recent theoretical work on congestion, implying that hub-airlines take into account the impact of their scheduling decisions on the congestion that they bear. The results may suggest that congestion management solutions implemented at hub airports dominated by one airline could have only a limited impact on congestion in general.     

Bottleneck Congestion and Modal Split

This paper analyzes commuting congestion when there is mass transit parallel to a road with a bottleneck between a residential area and a workplace. We investigate the optimality and efficiency of several railroad fare and road toll regimes and provide practical rules for attaining the social optimum. A welfare comparison is also made between these regimes, and it is shown that the road tolls are effective especially in the case of heavy road congestion.     

A bathtub model of downtown traffic congestion

In standard economic models of traffic congestion, traffic flow does not fall under heavily congested conditions. But this is counter to experience, especially in the downtown areas of major cities during rush hour. This paper analyzes a bathtub model of downtown rush-hour traffic congestion that builds on ideas put forward by William Vickrey. Water flowing into the bathtub corresponds to cars entering the traffic stream, water flowing out of the bathtub to cars exiting from it, and the height of water in the bathtub to traffic density. Velocity is negatively related to density, and outflow is proportional to the product of density and velocity. Above a critical density, outflow falls as density increases (traffic jam situations). When demand is high relative to capacity, applying an optimal time-varying toll generates benefits that may be considerably larger than those obtained from standard models and that exceed the toll revenue collected.     

Traffic density,congestion externalities,and urbanization in China

ABSTRACT

Although there is an abundant regional literature analyzing traffic congestion, only a few studies have explored extending such analysis with spatial effects. This study uses a dynamic spatial Durbin model and city-level panel data for the period 2003–14 to investigate the spatial spillover effects of traffic congestion on urbanization in China. The results show that there is an inverted ‘U’-shaped relationship between urbanization and traffic density in local and neighbouring cities, and congestion effects have appeared. In the short and long run, the spatial effects of traffic congestion have become an important force restricting the effective promotion of urbanization in China.     

The general equilibrium effects of congestion externalities

This is the second in a series of three articles on the topic of congestion externalities. We use an urban general-equilibrium model to compute two types of cities: the market-equilibrium city, in which congestion externalities occur, and the optimum city. The optimum city has a more dispersed distribution of employment, and a more concentrated distribution of residence. If the population of the city is fixed, the optimum pricing of transportation generates a per capita welfare gain of $3.78 per week. If the population of the city is endogenous, the internalization of congestion externalities causes the city to grow.     

Congestable local public goods in an urban setting

In this paper, we recognize two types of unpure local public goods (LPGs): congestable and pollutable. This paper and the forthcoming one (Clubs in an urban setting, mimeo, 1980) are devoted to congestable LPGs (CLPG). In Part I we define, classify, and characterize CLPGs. CLPGs may vary in their degree of congestability between zero, in the case of a pure LPG, and one, in the case of a private good. Spatially, we recognize two types of LPGs: the dispersed LPG (DiLPG) and the concentrated LPG (CoLPG). The first is distributed throughout the residential ring and the second is provided in specific locations to which households must travel. The second part of this paper is devoted to the investigation of the properties of a CDiLPG in an urban setting. The properties of CoLPG are investigated in (Clubs in an urban setting, mimeo, 1980). A version of Samuelson's rule as to the optimal allocation of pure public goods is extended on one hand to local dispersed public goods and on the other hand to CLPGs. Two corrective Pigouvian taxes are identified: congestion tolls levied on households, and a residential land tax. These two taxes cover total government expenditure on the LPG. The fraction of the expenses on the LPG covered by congestion tolls is α, and that covered by land taxes is (1 − α), where α is the degree of congestability. Efficiency can also be achieved by zoning the residential ring and regulating the housing density in it. This procedure may replace taxation and its advantage is that we can control a large number of externalities by a single set of zoning rules and regulations. An a posteriori rule to guide the local government as to the desirability of its actions is provided.