Showing papers in "Transportation Research Part A-policy and Practice in 2005"

Car use: lust and must. Instrumental, symbolic and affective motives for car use

Abstract: This paper reports results of two questionnaire studies aimed at examining various motives for car use. In the first study, a random selection of 185 respondents who possess a driving licence were interviewed. Respondents were recruited from the cities of Groningen and Rotterdam, The Netherlands. The sample of the second study comprised a random selection of 113 commuters who regularly travelled during rush hours in and around Rotterdam, a region in the west of the Netherlands. First, it was examined which categories of car use motives may be distinguished. As proposed by Dittmar’s (1992) [The social psychology of material possessions: to have is to be. Havester Wheatsheaf, Hemel Hempstead, UK; St. Martin’s Press, New York] model on the meaning of material possessions, results from both studies revealed that car use not only fulfils instrumental functions, but also important symbolic and affective functions. Second, it was studied to what extent these different motives are related to the level of car use. From the results of study 2, it appeared that commuter car use was most strongly related to symbolic and affective motives, and not to instrumental motives. Third, individual differences in the relative importance of the three categories of motives were investigated. In both studies, most group differences were found in the evaluation of the symbolic and affective motives (and not the instrumental ones). Especially frequent drivers, respondents with a positive car attitude, male and younger respondents valued these non-instrumental motives for car use. These results suggest that policy makers should not exclusively focus on instrumental motives for car use, but they should consider the many social and affective motives as well.

Port privatization, efficiency and competitiveness: Some empirical evidence from container ports (terminals)

Abstract: Few studies have investigated the quantitative relationship between port ownership structure and port efficiency with mixed results. This study applies a stochastic frontier model proposed by Battese and Coelli [Battese, G.E., Coelli, T.J., 1995. A model for technique inefficiency effects in a stochastic frontier production function for panel data. Empirical Economics 20, 325–332], which incorporates the inefficiency effect, to show whether port privatization is a necessary strategy for ports to gain a competitive advantage. While this stochastic frontier model has been used to a wide number of industries where the technical inefficiency effect is required, this method has rarely been employed to port industry. This study also investigates the determinants of port competitiveness. Both the principal component analysis (PCA) and the linear regression model are used to examine the effects of identified key factors on port competitiveness. Based on a sample of selected container terminals around the world, the results of this study have shown that private sector participation in the port industry to some extent can improve port operation efficiency, which will in turn increase port competitiveness. Another important determinant of port competitiveness is the adaptability to the customers’ demand. All these results provide some policy implications and guidance for port authorities and port operators in formulating effective strategies to improve their competitiveness vis-a-vis rivals.

Valuing Time and Reliability: Assessing the Evidence from Road Pricing Demonstrations

Abstract: This paper compares results from evaluations of two recent road pricing demonstrations in southern California. These projects provide particularly useful opportunities for measuring commuters’ values of time and reliability. Unlike most revealed preference studies of value of time, the choice to pay to use the toll facilities in these demonstrations is relatively independent from other travel choices such as whether to use public transit. Unlike most stated preference studies, the scenarios presented in these surveys are real ones that travelers have faced or know about from media coverage. By combining revealed and stated preference data, some of the studies have obtained enough independent variation in variables to disentangle effects of cost, time, and reliability, while still grounding the results in real behavior. Both sets of studies find that the value of time saved on the morning commute is quite high (between $20 and $40 per hour) when based on revealed behavior, and less than half that amount when based on hypothetical behavior. When satisfactorily identified, reliability is also valued quite highly. There is substantial heterogeneity in these values across the population, but it is difficult to isolate its exact origins.

Travel time use in the information age

Abstract: This paper, focused primarily on UK data and debates, considers the potential significance of travel time use within past, present and future patterns of mobility. In transport scheme appraisal, savings in travel time typically represent a substantial proportion of the benefits of a scheme—benefits used to justify its often enormous financial costs. Such benefits are founded on the assumption that travel time is unproductive, wasted time in-between ‘real’ activities and which should be minimised. Travel demand analysis treats travel time and activity time as separate, albeit acknowledging an interdependency. The paper challenges these approaches by exploring how travel time can be, and is, being used ‘productively’ as activity time, and what enhancements to time use might be emerging in the ‘information age’. Such undermining of the division between activities and travelling, and between activity time and travel time, may have major implications for future levels of mobility, for the modal distribution of travel, for the validity of current transport appraisal methodology and for the analysis of travelling within the information age. These issues are considered.

All Work and No Play? The role of instrumental and affective factors in work and leisure journeys by different travel modes

Abstract: This paper examines the relative importance that people attach to various instrumental and affective journey attributes when travelling either for work or for a leisure day trip and presents how journeys by various travel modes score on these attributes. Although not a comparative paper, data are presented for two studies which used some identical measurements: one on commuter journeys and one on leisure journeys. The results show that for work journeys, respondents tend to attach more importance to instrumental aspects, and especially to convenience than to affective factors. For leisure journeys, however, respondents appear to attach almost equal importance to instrumental and affective aspects, particularly flexibility, convenience, relaxation, a sense of freedom and 'no stress'. Each study also examines (i) how regular users' evaluate their own mode and (ii) how car users perceive the performance of alternative modes compared to their importance ratings. This 'gap' analysis reveals on which modes and for which attributes the greatest deficiencies in performance lie. The data for both the work and leisure studies shows that for car users, alternative transport modes are inferior on the salient attributes such as convenience and flexibility even though car users rate modes such as walking and cycling as performing well, if not, better, on less important attributes such as the environment, health and even excitement. Nevertheless, for those who cycle and walk regularly, satisfaction with their own travel mode as measured by the gap between importance and performance on salient attributes is better than for those who mostly use the car. Conclusions are made as to how greater attention to affective factors may improve our understanding of mode choice. (C) 2004 Elsevier Ltd. All rights reserved.

Estimation of value of travel-time savings using mixed logit models

Abstract: In this paper, we discuss some of the issues that arise with the computation of the implied value of travel-time savings in the case of discrete choice models allowing for random taste heterogeneity. We specifically look at the case of models producing a non-zero probability of positive travel-time coefficients, and discuss the consistency of such estimates with theories of rational economic behaviour. We then describe how the presence of unobserved travel-experience attributes or conjoint activities can bias the estimation of the travel-time coefficient, and can lead to false conclusions with regards to the existence of negative valuations of travel-time savings. We note that while it is important not to interpret such estimates as travel-time coefficients per se, it is nevertheless similarly important to allow such effects to manifest themselves; as such, the use of distributions with fixed bounds is inappropriate. On the other hand, the use of unbounded distributions can lead to further problems, as their shape (especially in the case of symmetrical distributions) can falsely imply the presence of positive estimates. We note that a preferable solution is to use bounded distributions where the bounds are estimated from the data during model calibration. This allows for the effects of data impurities or model misspecifications to manifest themselves, while reducing the risk of bias as a result of the shape of the distribution. To conclude, a brief application is conducted to support the theoretical claims made in the paper.

Travel behavior in neo-traditional neighborhood developments: A case study in USA

Abstract: Although previous research has supported the view that neo-traditional or new urbanist designs result in more walking activity, several questions remain: Do residents of these neighborhoods substitute walking for driving trips, or do they make more trips overall? What is the role of self-selection of residents in these developments? This paper aims to address these questions by examining differences in travel behavior in a matched pair of neighborhoods (one conventional and one neo-traditional) in Chapel Hill and Carrboro, North Carolina. A detailed behavioral survey of 453 households and two-stage regression models suggest that single-family households in the neo-traditional development make a similar number of total trips, but significantly fewer automobile trips and fewer external trips, and they travel fewer miles, than households in the conventional neighborhood, even after controlling for demographic characteristics of the households and for resident self-selection. The findings suggest that households in the neo-traditional development substitute driving trips with walking trips.

When is getting there half the fun? Modeling the liking for travel

Abstract: This paper analyzes empirically measured values of Travel Liking––how much individuals like to travel, in various overall, mode-, and purpose-based categories. The study addresses two questions: what types of people enjoy travel, and under what circumstances is travel enjoyed? We first review and augment some previously hypothesized reasons why individuals may enjoy travel. Then, using data from 1358 commuting residents of three San Francisco Bay Area neighborhoods, a total of 13 ordinary least-squares linear regression models are presented: eight models of short-distance Travel Liking and five models of long-distance Travel Liking. The results indicate that travelers’ attitudes and personality (representing motivations) are more important determinants of Travel Liking than objective travel amounts. For example, while those who commute long distances do tend to dislike commute travel (as expected), the variables entering the models that hold the most importance relate to the personality and attitudes of the traveler. Most of the hypothesized reasons for liking travel are empirically supported here.

A critical review of conventional terminology for classifying seaports

Abstract: Seaports are complex and dynamic entities, often dissimilar from each other, where various activities are carried out by and for the account of different actors and organisations. Such a multifaceted situation has led to a variety of operational, organisational and strategic management approaches to port systems. It is noticeable in the current body of port literature that the conceptualisation of the port business has taken place at different disciplinary levels without producing a comprehensive and structured port management discipline. Much of the current literature on ports has been developed by international organisations and institutions in the field (United Nations Conference on Trade and Development (UNCTAD), World Bank Group, etc.) and a resulting terminology has evolved depicting specific concepts hardly understood by professionals and academics outside the field. On the other hand, many areas of port operations and management still remain unexplored, and there are few academic references outlining the different features of operational and strategic management in ports. This paper examines the validity of the conventional terminology for classifying ports, questioning the assumption that ports should be conceptualised as separate markets and distinct operational and business ventures. It seeks to demonstrate that in today’s inter-related global markets and businesses with integrated logistics and supply chain flows, there is less of a case for the traditionally isolated and restricted port terminology.

Driving by choice or necessity

Abstract: From just about all accounts, Americans are driving more than ever, not just to work but to shopping, to school, to soccer practice and band practice, to visit family and friends, and so on. Americans also seem to be complaining more than ever about how much they drive—or, more accurately, how much everyone else drives. However, the available evidence suggests that a notable share of their driving is by choice rather than necessity. Although the distinction between choice and necessity is not always so clear, it is important for policy makers. For necessary trips, planners can explore ways of reducing the need for or length of the trip or ways of enhancing alternatives to driving. For travel by choice, the policy implications are much trickier and touch on basic concepts of freedom of choice. This paper first develops a framework for exploring the boundary between choice and necessity based on a categorization of potential reasons for and sources of “excess driving”, and then uses in-depth one-on-one interviews guided by this framework to characterize patterns of excess driving. This research contributes to a deeper understanding of travel behavior and provides a basis for developing policy proposals directed at reducing the growth in driving.

Credit-based congestion pricing: a policy proposal and the public’s response ☆

Abstract: Credit-based congestion pricing (CBCP) is a novel strategy proposed here. A revenue-neutral policy where road tolls are based on the negative externalities associated with driving under congested conditions, its generated tolls are returned to all licensed drivers in a uniform fashion, as a sort of driving “allowance”. Essentially, the “average” driver pays nothing, while frequent long-distance peak-period drivers subsidize others, in effect paying them to stay off congested roads. In order to anticipate initial public response to a CBCP policy, 500 individuals completed a detailed survey regarding perceptions of, and likely travel reactions to, such a policy. Weights were developed to correct for survey biases in gender, age and household income. Analytical results suggest that 25% support this new strategy, and support is strongly related to familiarity with the concept of congestion pricing. Respondent estimates of congested travel times to work or school are almost double the uncongested times. Values of travel time vary greatly across respondents, as also trip flexibility. Those without children, younger respondents, and those with fewer vehicles appear more willing to support such a policy and more likely to modify their travel behaviors. Older people and full time employed people were willing to pay higher CBCP tolls to drive during peak hours and so were men as compared to women. The survey results corroborate the potential of a CBCP policy to alleviate congestion and generate benefits across income groups and traveler types.

Modelling the effects of road pricing on traffic in Singapore

Abstract: With increasing worldwide interest in the application of urban road pricing, the experience of Singapore can be very useful. Under the Singapore Electronic Road Pricing (ERP) system, charges for entering the city centre and using some expressways vary by time of day and are being periodically revised in order to maintain traffic speeds within the desirable bands. Traffic response to these revisions shows that demand elasticity with respect to pricing is higher for cars than for other vehicles and higher for expressways than for the city centre cordon. It is also lower in the morning peak and higher in the afternoon. A discrete choice based model of motorist response to pricing is proposed for a single toll point with peak period variable pricing. The choices considered include the time interval of travel and re-routing to avoid the toll. The model was calibrated for one expressway and two arterial roads using only traffic volume data collected before and after ERP introduction. The model reflected well the peak spreading effect of variable road pricing and the penalties for rescheduling and re-routing of trips. In general, the Singapore experience suggests that variable pricing is an effective method of controlling congestion.

Congestion pricing on a road network: A study using the dynamic equilibrium simulator METROPOLIS

Abstract: The gradually accelerating pace at which tolls are being implemented or actively considered around the world suggests that road pricing is an idea whose time may finally have come. Nevertheless, various design considerations must be addressed and public acceptability hurdles overcome if road pricing is to become widespread. And to measure the efficiency gains and welfare-distributional effects of road pricing accurately, models need to account for potential behavioural responses to tolls—and in particular adjustments in trip timing. This paper analyzes some road pricing schemes using the dynamic network simulator METROPOLIS: a tool that treats endogenously departure-time decisions as well as mode and route choices of individual travelers. Simulations are conducted for a stylized urban road network that consists of radial arterials and circumferential ring roads, and with trip origins and destinations that are distributed throughout the network. Six types of link-tolling schemes are analyzed: (1) the system optimum which can be supported approximately by imposing time-varying step tolls that eliminate queuing, (2) a set of comprehensive flat (time-independent) tolls, (3,4) second-best flat and step tolls for a toll cordon, and (5,6) second-best flat and step tolls within a charge area. Two results show the superiority of step tolls over flat tolls. First, step tolls easily outperform flat tolls in terms of welfare gains while inducing a smaller shift of trips from auto to transit. Second, step tolls generate smaller revenues than do flat tolls, and consequently have more favourable distributional impacts on travelers.

Modelling safety-related driving behaviour—impact of parameter values

Abstract: Traffic simulation models make assumptions about the safety-related behaviour of drivers. These assumptions may or may not replicate the real behaviour of those drivers who adopt seemingly unsafe behaviour, for example running red lights at signalised intersections or too closely following the vehicles in front. Such behaviour results in the performance of the system that we observe but will often result in conflicts and very occasionally in accidents. The question is whether these models should reflect safe behaviour or actual behaviour. Good design should seek to enhance safety, but is the safety of a design necessarily enhanced by making unrealistically optimistic assumptions about the safety of drivers’ behaviour? This paper explores the questions associated with the choice of values for safety-related parameters in simulation models. The paper identifies the key parameters of traffic simulation models and notes that several of them have been derived from theory or informed guesswork rather than observation of real behaviour and that, even where they are based on observations, these may have been conducted in circumstances quite different to those which now apply. Tests with the micro-simulation model DRACULA demonstrate the sensitivity of model predictions—and perhaps policy decisions—to the value of some of the key parameters. It is concluded that, in general, it is better to use values that are realistic-but-unsafe than values that are safe-but-unrealistic. Although the use of realistic-but-unsafe parameter values could result in the adoption of unsafe designs, this problem can be overcome by paying attention to the safety aspects of designs. The possibility of using traffic simulation models to produce estimates of accident potential and the difficulties involved in doing so are discussed.

Reforms and infrastructure efficiency in Spain's container ports

Abstract: This paper quantifies the evolution of technical efficiency in port infrastructure service provision in the major Spanish port authorities involved in container traffic. The paper also analyzes the extent to which port reforms that took place in the 1990's had an impact on the efficiency of the Spanish container ports. Because of the multi-output nature of port activities, we have estimated a distance function, which is a novel methodology in the study of the port industry. The results show that the reforms resulted in significant improvements in technological change, but that technical efficiency has in fact changed little on average. However, there is a significant movement of the efficiency within ports over time as a result of these reforms.

The therapeutic value of children's everyday travel

Abstract: This paper looks at the role of travel as a facilitator and provider of children’s physical activity which is an essential part of a healthy lifestyle. Health issues are becoming an increasingly strong element in the utility associated with the choice of mode for children by parents. The paper draws on research in which 200 children were fitted with three-dimensional motion sensors and asked to keep travel and activity diaries over a period of four days. From these it is possible to establish what the children did, how they travelled and how much energy they used. The data are used to test two hypotheses: firstly that travel can increase children’s volume of physical activity by providing access to events that provide greater intensities of physical activity than being at home; and secondly that walking can provide significant volumes of physical activity in its own right.

Integrated scheduling of daily work activities and morning–evening commutes with bottleneck congestion

Abstract: Previous analysis of bottleneck congestion and departure time choice have focused on the trade-off between queuing delay cost and early/late arrival penalty for a given work start schedule.The actual scheduling of travel and work activities may well depend on some other important factors, such as the travel cost of the after-work trip, the work duration and the utility variation of different work times.This paper attempts to link the home-to-work and work-to-home trip schedules via the work duration.The morning home-to-work and evening work-to-home travel costs are calculated by the bottleneck queuing models and each individuals work utility is determined according to his/her work start time and end time with a predetermined marginal timing utility function.Travelers make a tradeoff between travel cost minimization and stay-at-home and work utility maximization in choosing their travel and activity schedules.A discrete choice model is used to predict the dynamic evolution process and stationary distribution of individual schedule patterns.After specifying various kinds of timing utility functions with different degrees of flexibility in work hour schemes, a set of numerical experiments are conducted and some meaningful observations are made from the experiment results, particularly on the effect of flexible work hours on traffic congestion mitigation. � 2004 Elsevier Ltd. All rights reserved.

Regulating taxi services in the presence of congestion externality

Abstract: In most large cities, the taxi industry is subject to various types of regulation, such as entry restrictions and price controls, and economists have examined the economic consequences of such regulation extensively. Unfortunately, in conventional economic analyses of competition and regulation in the taxi industry little attention has been paid to one important issue: congestion externalities due to both occupied and vacant taxi movements together with normal vehicular traffic. This study investigates the nature of equilibrium and regulation in the taxi market by taking account of congestion externalities and adopting a realistic distance-based and delay-based taxi fare structure. The monopoly, the social optimum and the stable competitive solutions are examined and illustrated with a numerical example.

Route switching behavior on freeways with the provision of different types of real-time traffic information

Abstract: This study investigates route switching behavior on freeways in reaction to the provision of different types of real-time traffic information. The experimental design of the stated preference survey is based on four types of real-time information provided to travelers who were randomly selected at rest areas. The four types of real-time information defined in this paper are qualitative, quantitative, qualitative guidance, and quantitative guidance. The bounded rationality framework, also known as indifference band approach, is applied to model the freeway route switching behavior. Two important variables, travel time and travel cost, are included in the indifference band. In this study, the best route switching rule, travelers’ current routes as compared to the best route, is investigated to further provide valuable insights into freeways travelers’ route switching behavior with the provision of different types of real-time traffic information.

A study of an integrated intercity travel demand model

Abstract: It is well reported that induced travel is an important component of travel demand. With improved transportation conditions, short run effects (e.g., route switches, mode switches, changes of destination, and new trip generation) and long term effects (e.g., change in household auto ownership, and spatial reallocation of activities) will be observed. This paper aims to develop an integrated intercity travel demand modelling system suitable for substantial changes in service level. The model utilizes combined estimation across multiple data sources such as SP, RP and aggregate data. This integrated intercity travel demand modelling system is characterized by an explicit intercity travel behavioural framework and its ability to capture induced travel. Intercity travel decisions are represented by a nested model structure, and an accessibility measure is introduced to capture short term induced travel. The paper also sketches a way to estimate induced travel resulting from long term changes (spatial reallocation of activities). As a case study, an integrated model including trip generation, destination choice, mode choice, and route choice is presented for an intercity high speed rail project planned in Japan, and short term induced travel elasticities with respect to travel cost, travel time, and etc. are also presented.

Modeling the competition among air-travel itinerary shares: GEV model development

Abstract: This study reports the results of aggregate air-travel itinerary share models estimated using data from all East West markets in the United States and Canada. These models predict airline ridership at the itinerary level and aid carriers in long and intermediate term decision-making. Official and comprehensive schedule and bookings data is used to estimate generalized extreme value models capturing the inter-itinerary competition dynamic along three dimensions: time of day, carrier and level-of-service (nonstop, direct, single-connect, double-connect). Models incorporate one, two or three of these dimensions simultaneously. Model structures considered include multinomial logit and variations of the nested logit model (two-level nested logit, two-level weighted nested logit, three-level nested logit, three-level weighted nested logit and nested weighted nested logit). Independent variables for the models measure various itinerary service characteristics such as level-of-service, connection quality, carrier attributes, aircraft type, and departure time. Additionally, the advanced models yield inverse logsum and/or weight parameter estimates capturing the underlying competitive dynamic among air-travel itineraries. The results are intuitive, and the advanced models outperform the more basic specifications with regard to statistical tests and behavioral interpretations, giving insight into the competitive dynamic of air-carrier itineraries.

Congestion and safety: A spatial analysis of London

Abstract: A disaggregate spatial analysis, using enumeration district data for London was conducted with the aim of examining how congestion may affect traffic safety. It has been hypothesized that while congested traffic conditions may increase the number of vehicle crashes and interactions, their severity is normally lower than crashes under uncongested free flowing conditions. This is primarily due to the slower speeds of vehicles when congestion is present. Our analysis uses negative binomial count models to examine whether factors affecting casualties (fatalities, serious injuries and slight injuries) differed during congested time periods as opposed to uncongested time periods. We also controlled for congestion spatially using a number of proxy variables and estimated pedestrian casualty models since a large proportion of London casualties are pedestrians. Results are not conclusive. Our results suggest that road infrastructure effects may interact with congestion levels such that in London any spatial differences are largely mitigated. Some small differences are seen between the models for congested versus uncongested time periods, but no conclusive trends can be found. Our results lead us to suspect that congestion as a mitigator of crash severity is less likely to occur in urban conditions, but may still be a factor on higher speed roads and motorways.

Assessment of economic impacts from unexpected events with an interregional commodity flow and multimodal transportation network model

Abstract: Loss and damage caused by unscheduled events, especially earthquakes, have sudden and significant impacts not only on the region’s economy where the event occurs but also on other regions. The New Madrid Seismic Zone, located in the center of the United States, could have great impacts on economic activities related to this area, if a major earthquake occurred. Based on the 1993 US Commodity Flow Survey [US Commodity Flow Survey, 1993. Available from: http://www.bts.gov/ntda/cfs/prod.html >], more than 42% of total commodity flows in the US are related to the greater Midwest, which includes the New Madrid Seismic Zone. If a catastrophic earthquake occurred in this area, the indirect damages could spread far beyond the region, and could have sizable impacts on other regions. A model of interregional commodity flows, incorporating regional input–output relationships, and the corresponding transportation network flows, was applied to assess the economic impacts of such an unexpected event. The economic impacts from the event are described for three hypothetical scenarios, analyzing the magnitude and the extent of the direct and indirect impacts. These analytical results may be used to propose strategic management of the recovery and reconstruction efforts after the event.

Implications of Congestion Charging for Departure Time Choice: Work and Non-Work Schedule Flexibility

Abstract: The objective of this paper is to investigate the potential impacts of implementing variable congestion charging on the peak spreading of departure time choices, taking into account levels of scheduling flexibility of individuals. In particular, this study addresses non-work activities as well as socio-economic characteristics and their influence on scheduling flexibility for work trips. Departure time choice models were calibrated using data collected as part of a larger survey on the consequences of congestion charging on travel choices in the city of Edinburgh. The inclusion of variables related to work and non-work scheduling, as well as socio-economic variables have improved the performance of the models. This suggests that non-work activities, as well as work schedule flexibility have an impact on departure time choice for the journey to work. This means that even for those with flexible work schedules, but with other non-work commitments, the timing of their work trip may not be so flexible. Therefore, for the success of variable congestion charging schemes, other complimentary measures should be introduced in parallel. These include, for example, child care provision at work, opening hours of shops and leisure facilities.

Information gain, novelty seeking and travel: a model of dynamic activity-travel behavior under conditions of uncertainty

Abstract: When making a trip, individuals make observations that may increase their knowledge about their environment. In this paper, we develop a measure of expected information gain based on a Bayesian model of mental maps and belief updating. We argue that expected information gain is an element of the utility function of trip choice alternatives under conditions of limited information and learning. Theory and models are developed. The simulations conducted illustrate that expected information gain tends to favor longer trips and variety seeking in terms of both route and destination choice. We argue, therefore, that individuals may perceive a positive utility of travel through environments with which they are less familiar.

Measuring inaccuracy in travel demand forecasting: methodological considerations regarding ramp up and sampling

Abstract: Project promoters, forecasters, and managers sometimes object to two things in measuring inaccuracy in travel demand forecasting: (1) using the forecast made at the time of making the decision to build as the basis for measuring inaccuracy and (2) using traffic during the first year of operations as the basis for measurement. This paper presents the case against both objections. First, if one is interested in learning whether decisions about building transport infrastructure are based on reliable information, then it is exactly the traffic forecasted at the time of making the decision to build that is of interest. Second, although ideally studies should take into account so-called demand “ramp up” over a period of years, the empirical evidence and practical considerations do not support this ideal requirement, at least not for large-N studies. Finally, the paper argues that large samples of inaccuracy in travel demand forecasts are likely to be conservatively biased, i.e., accuracy in travel demand forecasts estimated from such samples would likely be higher than accuracy in travel demand forecasts in the project population. This bias must be taken into account when interpreting the results from statistical analyses of inaccuracy in travel demand forecasting.

Micro-foundations of congestion and pricing: A game theory perspective

Abstract: This paper develops congestion theory and congestion pricing theory from its micro-foundations, the interaction of two or more vehicles. Using game theory, with a two-player game it is shown that the emergence of congestion depends on the players’ relative valuations of early arrival, late arrival, and journey delay. Congestion pricing can be used as a cooperation mechanism to minimize total costs (if returned to the players). The analysis is then extended to the case of the three-player game, which illustrates congestion as a negative externality imposed on players who do not themselves contribute to it.

Cordon-based congestion pricing in a continuum traffic equilibrium system

Abstract: This paper presents an application of the continuum traffic equilibrium model for the cordon-based congestion pricing problem. The traffic equilibrium model treats densely spaced roads as a continuum over which commuters are continuously dispersed. Suppose in the morning peak-hour, all commuters travel to the central business district (CBD) by taking their individual shortest routes. Their user-optimal route choice behavior, with or without toll pricing, can be formulated as a calculus of variations problem and solved efficiently by the modern finite element method. By plotting the numerical results in a two-dimensional space in the form of contour lines of travel cost to the CBD, one can intuitively identify the level of congestion and the external cost anywhere in the city. Hence, the continuum model and two-dimensional numerical representation allow a traffic planner to select easily one or multiple toll cordon(s) in the city and evaluate the impact of cordon toll charges on the resultant social welfare and user benefits.

Pedestrian delay estimation at signalized intersections in developing cities

Abstract: This paper proposes a pedestrian delay model suitable for signalized intersections in developing cities, on the basis of a field study conducted in Xi’an, China. The field study consisted of two parts: Part I involved only one crosswalk, and the signal cycle was divided into 13 subphases; Part II involved 13 crosswalks, but the signal cycles were only divided into green phases and non-green phases. It was found that pedestrian arrival rates were not uniform throughout cycles; pedestrians arriving during green phases might also receive delays; pedestrian signal non-compliance was so severe that delays were greatly reduced, but non-complying pedestrians might still receive delays; and for pedestrians walking different directions, though the relationships between average delay and arrival subphase were different, the overall average delays were almost the same. On the basis of the field study results, some assumptions are made about the relationship between average pedestrian delay and arrival subphase, and a new model is developed to estimate pedestrian delays at signalized intersections. The model is validated using the field data, and the validation results indicate that in Xi’an the new model provides much more accurate estimation than the existing models.