Uniform versus peak-load pricing of a bottleneck with elastic demand

This paper considers commuting to work across a bottleneck such as a bridge or tunnel, with elastic demand. With no toll, there is wasteful queueing. The optimal peak-load toll eliminates queueing and leaves total traffic unchanged. The second-best uniform toll cannot eliminate queueing, but reduces total traffic. The second-best uniform toll may be larger or smaller than the maximum value of the optimal peak-load toll.     

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.     

Commuter Responses to Travel Time Uncertainty under Congested Conditions: Expected Costs and the Provision of Information

A simulation methodology for analyzing policies for reducing traffic congestion and the effect of providing commuters with pre-trip information is developed. This combines a model incorporating travel time uncertainty to determine optimal home departure times with a supply-side congestion model of a highway facility. Congestion is endogenously generated for different scenarios using a randomly generated normal distribution of work start times and previously estimated parameters. The results suggest that greater reductions in the expected costs of commuting may be achievable by policies that reduce travel time variance rather than just travel times. Policy simulations which analyze the congestion effects of providing commuters with pre-trip information are found to not necessarily provide many benefits to those using the information, although gains may be minor because the only behavioral response is limited to departure time changes.     

Hypercongestion in downtown metropolis

Engineering studies demonstrate that traffic in dense downtown areas obeys a stable functional relationship between average speed and density, including a region of ‘hypercongestion’, where flow decreases with density. This situation can be described as queuing behind a bottleneck whose capacity declines when the queue is large. We combine such a variable-capacity bottleneck with Vickrey scheduling preferences for the special case, where there are only two possible levels of capacity. Solving the model leads to several new insights, including that the marginal cost of adding a traveler is especially sensitive to the lowest level of capacity reached. We analyze an optimal toll, a coarse toll, and metering, showing substantial benefits from using these policies to eliminate the period of reduced capacity. Under hypercongestion, all of these policies can be designed so that travelers gain even without considering any toll revenues.     

公交实时信息化服务对乘客出行行为意向影响

为了解城市公交信息化服务对公交乘客出行方式转移的影响,以上海市杨浦区为例,进行关于公交信息化服务下乘客出行方式转移的调查,获取个人属性、公交出行经历、公交出行评价、出行方式转移意向以及公交信息服务需求等信息。从公交信息使用者角度,重点关注公交信息化服务对乘客出行方式转移的影响,分别构建信息化服务情境下(公交到站时间与计划出发时间相差过大和车辆未在提示的时间内到达)的公交出行方式转移二项logit模型。模型结果表明:乘客平均候车时间、是否经常使用公交到站服务、是否有道路拥挤车辆未按时进站等原因而产生出行延误的经历、公交信息准确性评价与是否有必要提示同公交线路连续班次的到站时间等因素对不同情景下的乘客出行方式转移具有显著影响。     

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.     

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.     

Timing Equilibria in an Urban Model with Congestion

All spatial urban models with congestion assume that the departure (arrival) time of commutes is exogenously determined and assume that travel speed at a given time and location depends upon the traffic density at that point in time and space. This paper presents a framework that encompasses such models, but allows workers to choose the time at which they leave home (arrive at work). This paper then proves that in general only one equilibrium exists for urban models with traditional congestion technology: a commuting pattern in which commuting is continuous and the rush hour never ends, which is unrepresentative of traffic patterns anywhere. This paper concludes by discussing alternative general equilibrium urban models with congestion that may have more realistic equilibria.     

Optimal road capacity in the presence of unpriced congestion

This paper studies how the optimal capacity of a road is affected by a pricing constraint which keeps the toll fixed below its optimal value. The answer is found to depend on the value of the price elasticity of travel demand at the second-best optimum. The pricing constraint lowers the optimal capacity, if the price elasticity is sufficiently high. But under reasonable assumptions, the pricing constraint raises the optimal capacity, if the price elasticity is less than the ratio of the consumer price of travel to the private congestion cost at the second-best optimum. This ratio cannot be less than one.     

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.     

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.     

智能交通中单车辆最优动态路径规划策略研究

目前的交通现状,使人们无时无刻不在感受着交通拥挤、事故频发、尾气过度排放、能源供给失衡等问题,这些问题已经成为经济可持续发展中不可回避的障碍。智能交通方案是解决交通问题的一场信息化革命,动态最优路径规划策略作为智能交通出行者信息管理系统的重要问题,非常有必要值得研究。本文首先建立单车辆动态数学模型,采用基于周期的自主车辆规划算法,有效的避免拥挤的交通路段,使车辆出行代价降低,提高了车辆路径规划的实时效果和准确度。     

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.     

Travel time and transportation policy

This paper examines the relationship between traffic congestion and travel time. A model is developed where both travel time and the number of peak-hour trips are simultaneously determined. The model is estimated by two-stage least squares using traffic data from the Boston metropolitan area. The estimates are used to generate implications for transportation policy. The paper suggests that commuters are substantially more responsive to changes in travel time than to changes in price.     

Optimal highway design and user welfare under value pricing

This paper investigates the optimal design of highways operated under a form of congestion pricing called value pricing. Value pricing involves dividing a highway into free and priced lanes so that in equilibrium the highway effectively operates at two levels of service, with those users placing a higher value on travel time savings selecting the faster, priced route. A tractable analytical framework is developed which allows analysis of equilibrium and welfare on value priced highways when users vary in their value of time. The model is used to characterize optimal toll and capacity policies, as well as investigate the fiscal implications of value pricing. The analysis concludes with results on how welfare changes induced by value pricing are distributed over the population of users when the government finances any funding shortfall through a non-discriminatory taxing mechanism. A realistic numeric example is used to illustrate how the model can be applied to evaluation of actual and proposed value pricing implementations.     

基于行程费用的城市物流配送通道选择模型

从时间质量的角度出发,指出行程时间最小化和行程时间可靠性最大化是城市物流配送通道选择的两个重要目标。定义行程费用等于行程时间费用和行程时间可靠性费用的加权平均值。在此基础上,建立了基于行程费用的物流配送通道选择模型。最后,对北京市实际路网进行了实例分析。     

基于百度地图实时路况的昆明市道路拥堵研究

基于百度地图实时路况的调查资料,应用ArcGIS中全局空间自相关分析模块和局部空间聚集性模块方法,对昆明市交通拥堵进行时空分布特征研究。结果显示全局聚集分析中昆明市交通拥堵点呈现聚集性分布,局部空间聚集性分析中昆明市交通拥堵点局部聚集性强,分布区域集中在商业、客运中心和旅游休闲区域,空间上临近区域拥堵情况类似,土地利用性质对周围的交通存在显著的影响。拥堵的时间规律特征主要受人们活动规律的影响。     

基于MapX的城市交通系统最优路径的研究与应用

文章论述了根据城市交通的特点,以Mapx为基础建立适用于城市交通的道路拓扑结构,并在此基础上考虑车流量、道路最高限速等因素,寻求从出发地到目的地所需时闻最短的路径。     

Financing Capacity in the Bottleneck Model

It is well known that, for a congestible facility with constant long-run average cost, the revenue from the unconstrained optimal congestion charge (set so that each individual faces the marginal (social) cost of a use) exactly covers the cost of optimal capacity. In the context of Vickrey′s bottleneck model of morning rush-hour auto congestion, this paper investigates under what circumstances the first-best pricing and investment rules apply when both the time variation of the congestion charge is constrained and users differ in unobservable characteristics so that the same congestion charge must be applied to heterogeneous users.     

基于MapX的城市交通系统最优路径的研究与应用

文章论述了根据城市交通的特点,以MapX为基础建立适用于城市交通的道路拓扑结构,并在此基础上考虑车流量、道路最高限速等因素,寻求从出发地到目的地所需时间最短的路径.