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.     

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.     

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.     

Trip-timing decisions with traffic incidents

This paper analyzes traffic bottleneck congestion when drivers randomly cause incidents that temporarily block the bottleneck. Drivers have general scheduling preferences for time spent at home and at work. They independently choose morning departure times from home to maximize expected utility without knowing whether an incident has occurred. The resulting departure time pattern may be compressed or dispersed according to whether or not the bottleneck is fully utilized throughout the departure period on days without incidents. For both the user equilibrium (UE) and the social optimum (SO) the departure pattern changes from compressed to dispersed when the probability of an incident becomes sufficiently high. The SO can be decentralized with a time-varying toll, but drivers are likely to be strictly worse off than in the UE unless they benefit from the toll revenues in some way. A numerical example is presented for illustration. Finally, the model is extended to encompass minor incidents in which the bottleneck retains some capacity during an incident.     

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.     

Fuzzy modelling of static system optimum traffic assignment problem having multi origin-destination pair

Traffic congestion is an unpreventable problem to avoid in a transportation network and it has negative effects on traffic accident, time wasting, traffic delay and safety problem. Besides, in transportation networks, drivers do not want to deal with traffic jam while traversing between specified origin-destination pair. Therefore, traffic assignment (TA) is imperative to improve traffic management, transportation safety, time, and cost savings. System Optimum Traffic Assignment Problem (SOTAP) is a kind of TA model which aims to minimize the total system travel time on the network, and satisfies the flow conservation constraints. To model the SOTAP more realistically, the imprecise parameters can be taken as fuzzy. Therefore, in this paper, we focus on converting the conventional SOTAP to a fuzzy quadratic programming problem (QPP) which is named System Optimum Fuzzy Traffic Assignment Problem (SOFTAP). Here, link travel time is expressed with BPR function as generally used in the literature by converting to fuzzy except link-dependent parameters. Thus, the nonlinear objective function of SOFTAP is expressed in terms of fuzzy link flows and fuzzy link travel times. A solution approach from the literature is modified to the reconstructed SOFTAP.     

Carpooling and driver responses to fuel price changes: Evidence from traffic flows in Los Angeles

We examine carpooling and driver responses to fuel price changes. Using a simple theoretical model, we show that traffic flows in mainline lanes unambiguously decrease when fuel prices increase, and this effect is stronger when the presence of a carpool lane provides a substitute to driving alone. In contrast, in carpool (HOV) lanes flow can either increase or decrease. These predictions are tested using 8 years of traffic flow data for 1700 locations in Los Angeles. In our preferred specification, the mean elasticity of flow with respect to fuel price is 0.136 for HOV lanes. For a 10% increase in fuel price this implies 10 additional carpools per hour, $8.8 million per year in additional congestion costs for carpoolers and $11.3 million lower costs for mainline drivers. For mainline lanes, flow elasticities are −0.083 and −0.050 for highways with and without an HOV lane. These estimates imply that the mean highway with an HOV lane experiences a 30% larger decrease in hourly flow compared to the mean highway without an HOV lane. Flows in HOV lanes show an immediate decrease following a price increase but respond positively to price increases over time, which suggests time is an important input to carpool formation.     

Traffic externalities in cities: The economics of speed bumps,low emission zones and city bypasses

This paper considers various policy measures that governments can use to reduce traffic externalities in cities. Unlike much of the available literature that emphasized congestion, we focus on measures that reduce pollution, noise and some accident risks. These measures include noise barriers, speed bumps, traffic lights, tolls, emission standards, low emission zones, and bypass capacity to guide traffic around the city center. Using a simple model that distinguishes local and through traffic, we study the optimal use of these instruments by an urban government that cares for the welfare of its residents, and we compare the results with those preferred by a federal authority that also takes into account the welfare of road users from outside the city. Our results include the following. First, compared to the federal social optimum, we show that the city government will over-invest in externality-reducing infrastructure whenever this infrastructure increases the generalized cost of through traffic. We can therefore expect an excessive number of speed bumps and traffic lights, but the right investment in noise barriers. Second, when implementing low emission zones, the urban government will set both the fee for non-compliance and the emission standard at a more stringent level than the federal government. Moreover, at sufficiently high levels of through traffic the urban government will prefer imposing a toll instead of implementing a low emission zone. Third, whatever the tolling instruments in place, the city will always underinvest in bypass capacity. Finally, if it can toll all roads but is forced to invest all bypass toll revenue in the bypass, it will never invest in bypass capacity. Although the paper focuses on non-congestion externalities, most insights also hold in the presence of congestion.     

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.     

Multivariate time series analysis of traffic congestion measures in urban areas as they relate to socioeconomic indicators

Traffic congestion has significant adverse implications for the environment and economy. Many state and local transportation agencies have implemented traffic congestion management practices to alleviate the negative implications of urban traffic. One of the major drawbacks of traffic congestion management practices is that they do not account for socio-demographic and economic factors, which have a significant impact on traffic congestion. Understanding the influence of these factors is very crucial because they can help to communicate the system's performance management and target setting. Only a few studies analyzed the relationship between traffic conditions (e.g., traffic demand and vehicular traveling speed) with a limited number of socio-economic factors. Moreover, most of the existing models ignore the temporal and spatial autocorrelations of traffic congestion, which may significantly limit their reliability and effectiveness. This study is developed with the purpose of identifying the most relevant external factors that affect traffic congestion performance measures. To conduct the research, we have used three urban congestion performance measures collected from 51 metropolitan areas across the U.S. over a four-year period, 2013–2016: travel time index, planning time index, and congested hours. We have used multivariate time series models to account for the complex inter-relationships among the performance measures and socioeconomic factors to identify the most influential factors affecting system performance. We have finally developed predictive models to estimate the traffic congestion measures using these factors. The results of rigorous modeling show that the factors influencing the traffic congestion measures are monthly average daily traffic (MADT), the number of employed, rental vacancy rate, building permits, fuel price index, and Economic Conditions Index (ECI). The prediction models indicated that the effects of these factors are statistically significant and could be used to forecast future trends in three performance measures accurately.     

The social cost of through traffic: Contribution to the suburban-central city exploitation thesis

This paper deals with the conflict between local and through traffic when allocating land for transportation at the expense of residential consumption. The model developed in this paper gives the optimal allocation of land between both uses, via Pontryagin's Maximum Principle, and shows the impact of through traffic on the urban structure, on local transportation costs and on the cost of housing supply. The cost functionals are used to measure the total burden to the inner city and a connection is made to the ongoing discussion of the ‘exploitation’ thesis.     

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.     

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.     

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.     

A model of population distribution,traffic congestion,and neighborhood crowding in a circular city

An idealized static equilibrium model of a circularly symmetric city is presented. The model allows one to compute the spatial distribution of residences, given certain simple and plausible assumptions about the “costs” of transport, housing and neighborhood crowding. The model is chosen so as to guarantee that in first approximation, the residential population distribution which would be considered optimal by a perfect planner is identical to the distribution reached in a push-shove, laissez-faire equilibrium. This aspect of the construction is shown to be related in a simple way to the familiar “external diseconomy” situation in which a free resource is allocated among alternative uses by equating average, rather than marginal products. The existence of an infinite class of models in which the associated planner's optimum and laissez-faire equilibria are equivalent follows naturally from the standard theory of the private and social costs of highway congestion. The model leads naturally to exponentially falling population distributions which exhibit an “urban-suburban” dichotomy, to a particular overall city size, and to an optimal allocation of land between transport and residential uses.     

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.     

Peak-Load Pricing of a Bottleneck with Traffic Jam

This paper generalizes the model of bottleneck congestion such that formation and development of traffic jams is explicitly formulated. The model is applied to the peak-load problem for the morning rush hour: every morning, a fixed number of commuters travel across a roadway, and each of them chooses departure time to minimize commuting cost consisting of travel time cost, scheduling cost, and toll. Equilibrium and optimal patterns of departure are solved and optimal peak-load toll is derived. Incorporating traffic jams alters the earlier results in the literature. That is, road users may be better off from paying the optimal peak-load toll. Conditions under which such a result is obtained are identified by simulations.     

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.     

基于物流成本视角的车联网技术应用项目风险及控制研究

车联网是物联网最具发展前景的应用之一,因其可有效缓解城市交通拥堵、加快运输和配送速度、优化车辆行驶路线、减少运输和配送成本,使生产和销售更有可预测性等优势而受到运输和配送成本居高不下的物流行业高度重视。但由于前期投入较大,技术标准存在差异,网络安全、市场需求还需培育等因素,使得车联网技术应用项目存在一定的风险。国家应加强统筹规划,避免重复建设、减少社会投入总成本;积极推广多元化的投资主体,提高企业参与积极性;创新商业模式,发展专业细分市场。     

Second-Best Congestion Pricing: The Case of an Untolled Alternative

This paper deals with second-best one-route congestion pricing in case of an untolled alternative. Using a two-link network simulation model, the effects of various demand and cost parameters on the relative efficiency of one-route tolling are analyzed. It is investigated whether the existence of costs of congestion charging may be a reason for one-route tolling to be more “overall efficient” than two-route tolling. Finally, the efficiency of revenue-maximizing one-route and two-route tolling is discussed.