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Carpooling promises benefits to the environment and consumers alike, but research has shown that there are multiple practical challenges to realizing these benefits. One possible solution is the addition of meeting points (hubs) in the design of carpooling systems. Recent studies indicate that introducing hubs increases both carpool participation and system-wide savings. Little to no research has been conducted, however, to understand the origin of these savings, determine their utility in different carpooling models, or detailing how hubs should be introduced (i.e. as a mandate or option). Additionally, we know nothing about the impact of hubs on self-organizing carpools (the primary means of creating carpooling systems). To address these gaps, we studied the impact of meeting points on two types of carpooling models (pick-up/drop-off and to/from), using two solution paradigms (centralized and self-organized), with hubs that were either mandated or optional. Our findings show that adding the option of meeting hubs improves system-wide savings from carpooling. These findings, along with our introduction of a new efficient carpool enumeration technique, have important practical implications for the design of modern carpooling systems in the development of more effective and sustainable uses of transportation resources. [ABSTRACT FROM AUTHOR]

Carpooling is an environmentally friendly transportation system. It can efficaciously help resolve a variety of societal concerns of the urban areas, ranging from traffic congestion to environmental pollution. In this paper, we propose a new mathematical model to solve the carpooling problem. The model simultaneously minimizes the costs of travel times, the vehicle use, and the vehicle delays. An exact solution method based on Branch-and-Bound (B&B) algorithm is proposed to efficiently obtain the optimal solution of the problem. In order to find the near-optimal solutions for large-scale problems, a heuristic beam search algorithm is introduced, which is based on the partial relaxation of some fathoming criteria applied in our proposed B&B. The computational experiments are conducted, based upon the transportation network of Isfahan city, Iran. The results demonstrate the great capability of the proposed exact solution method in terms of both computational solving time required and the number of the evaluated nodes, in comparison with CPLEX software package. The findings of this research can be applied to solve the carpooling problem compatible to the real-life situations. [ABSTRACT FROM AUTHOR]

Existing carpool optimization techniques based on the centralized approach serve policy-makers' goals, but neglect the realities of participants. Moreover, absent strict enforcement, participants often ignore centralized solutions and maximize their own savings. We present a new heuristic, formulated and tested on real-world, and simulated car pooling problem instances, that mimics a decentralized carpool self-organization process. Our findings reveal system-wide savings similar to centralized models, and a potential strategy for improving carpool utilization. [ABSTRACT FROM AUTHOR]

Carpooling can be understood as an informal agreement between several individuals to share a privately owned car for a trip and to contribute to its expenses. It represents one of the most appealing strategies for reducing car use since it could reduce the number of kilometres driven by car, save money, and contribute to lowering CO 2 emissions. Despite these advantages, and even if accepted and somewhat practiced, carpooling is still underused. The aims of this study are to investigate for which type of everyday trips French drivers use carpooling, to analyze their characteristics, and determine whether the motivations for carpooling are different for each type of trip, as well as to find out whether the motivation changes according to the number of carpooled trips. 634 carpool drivers and/or passengers (aged 19–75 years, M  = 43.85, SD  = 12.05, 42.7% men) were recruited to answer an online survey. Factual data (socio-demographics, transportation accessibility) and motivational factors (attitudes regarding car use, public transportation, environment) were used to describe and explain carpooling for four types of trips (work, children, leisure, and shopping). Carpooling was most frequently used for leisure trips, followed by shopping, and then by work and children trips. Among the motivations underlying carpooling, most notable were the following: perceived pressure from family and peers (for all types of trips) and public transportation attitudes. Finally, motivations for carpooling use differed according to whether participants carpool for one, two, three or four trips, regardless of the type of trip. [ABSTRACT FROM AUTHOR]

Nowadays, ride-hailing services have been established as a part of the urban transportation. Their arrival has remade the profit structure and resulted in the unbalance of interest in taxi market. Here, we establish the service models of taxis, carpooling, and car-hailing under “Internet +” from the perspective of profit margins, to perform a comparative analysis among the different services. Results: First, Profit margins are generally higher for short trips than for long trips, though empty cruise fee to a certain degree make up for the driver’s decreased profit margins. Second, the profit margin for carpooling is roughly 1.85 times that of ride-hailing, and 1.75 times that of taxis. This shows that the sharing economy has a certain advantage. Third, Profit margins are higher and fluctuations are lower on non-work days than on work days. At last, Profit margins are roughly 1.3 times higher on non-congested roads than on congested roads. The reduced profitability on congested roads makes it even harder to catch a ride during rush hours and on congested roads. We suggest that the relevant departments make appropriate efforts to make it more attractive for drivers to take on passengers during rush hours and on congested roads, and promote the sharing in the taxi market. [ABSTRACT FROM AUTHOR]

Carpooling is an effective means of reducing traffic. A carpool team shares a vehicle for their commute, which reduces the number of vehicles on the road during rush hour periods. Carpooling is officially sanctioned by most governments, and is supported by the construction of high-occupancy vehicle lanes. A number of carpooling services have been designed in order to match commuters into carpool teams, but it known that the determination of optimal carpool teams is a combinatorially complex problem, and therefore technological solutions are difficult to achieve. In this paper, a model for carpool matching services is proposed, and both optimal and heuristic approaches are tested to find solutions for that model. The results show that different solution approaches are preferred over different ranges of problem instances. Most importantly, it is demonstrated that a new formulation and associated solution procedures can permit the determination of optimal carpool teams and routes. An instantiation of the model is presented (using the street network of Guangzhou city, China) to demonstrate how carpool teams can be determined. [ABSTRACT FROM AUTHOR]

With the rising fuel costs, ride sharing is becoming a common mode of transportation. Sharing taxis which has been prominent in several developing countries is also becoming common in several cities around the world. Sharing taxis presents several advantages as it minimizes vacant seats in cars thus reducing costs on taxi operators which results in significantly lower taxi fares for passengers. Besides the economical advantages, taxi sharing is highly important for reducing congestion on the roads and for minimizing the impact of transportation on the environment. In this paper, we formulate the problem of assigning passengers to taxis and computing the optimal routes of taxis as a mixed integer program. To solve the proposed model, we present a Lagrangian decomposition approach which exploits the structure of the problem leading to smaller problems that are solved separately. Furthermore, we propose two heuristics that are used to obtain good quality feasible solutions. The Lagrangian approach along with the heuristics are implemented and compared to solving the full problem using CPLEX. The computational results indicate the efficiency of the methodology in providing tighter bounds than CPLEX in shorter computational time. [ABSTRACT FROM AUTHOR]

Proponents of High Occupancy Vehicle (HOV) lanes claim the lanes reduce vehicle-trips by encouraging more people to carpool, but the evidence is mixed. This article reviews studies on the impacts of HOV lanes with a focus on behavioral models. This research makes a case for performance measures with direct welfare, congestion, or air pollution effects and focuses on papers that explicitly model carpool formation and allow for induced demand. Papers on individual regions find that HOV lanes may increase or decrease welfare, while more general papers find that the impact of HOV lanes depends on underlying parameters. The Clean Air Act assumes that HOV lanes reduce traffic volume and improve air quality and recommends HOV lanes to areas with poor air quality. This research finds there is no consensus on HOV lane impacts and, that using HOV lanes as a travel control measure may be misguided, but that further research is warranted. [ABSTRACT FROM PUBLISHER]

Some of the transportation energy consumed during peak commuter periods is wasted through slow running in congested traffic. Strategies to increase average vehicle occupancy (and reduce vehicle counts and congestion) could be expected to be at the forefront of energy conservation policies. Casual carpooling (also called "slugging") is a system of carpooling without trip-by-trip pre-arrangement. It operates in three US cities, and has been suggested in New Zealand as a strategy for managing transportation challenges when oil prices rise. The objective of the paper is to find out if casual carpooling reduces energy consumption, and if so, how much. Energy consumption by single occupant vehicles; casual carpool vehicles; and a mix of buses and single occupant vehicles; are estimated and compared, and the impact on the rest of the traffic is calculated. The paper estimates that casual carpooling in San Francisco is conserving in the order of 1.7 to 3.5 million liters of gasoline per year, or 200-400 liters for each participant, much of which comes from the impact on the rest of the traffic. The paper concludes by calling for applied research to discover how to catalyze casual carpooling in other cities as a means of reducing transportation energy consumption. [ABSTRACT FROM AUTHOR]

Increasing urban traffic congestion calls for the study of alternative measures. One such measure is carpooling, a system in which a person shares his private vehicle with one or more people in a commuter trip. In principle, this system could lead to potentially significant reductions in the use of private vehicles; however, in practice it has achieved limited success. In this paper, we apply a simulation-based methodology that uses aggregated data from commuter trips in an urban area to create compatible and feasible random trips. These are then analyzed through a heuristic process recursively to find grouping possibilities, thus producing indicators of carpooling potential such as the percentage of matched trips. Using this methodology, simulations are run for the Lisbon Metropolitan Area (Portugal) and results show that an increase in the number of participants in a carpooling scheme will only increase the probability of matching up to a certain point, and that this probability varies significantly with time-space trip attributes. [ABSTRACT FROM AUTHOR]

Abstract: Using structural equation modeling, the relationships among travel amounts, perceptions, affections, and desires across five short-distance (one-way trips of less than 100 miles) travel categories (overall, commute, work/school-related, entertainment/social/recreation, and personal vehicle) are examined. The models are estimated using data collected in 1998 from more than 1300 working commuters in the San Francisco Bay Area. A cross-model analysis reveals three robust relationships, namely: (1) myriad measures of travel amounts work together to affect perceptions; (2) perceptions are consistently important in shaping desires; and (3) affections have a positive relationship with desires. The second finding suggests that two individuals who travel the same objective amount may not have the same desire to reduce their travel: how much individuals perceive their travel to be is important. The third point argues that the degree to which travel is enjoyed is a key determinant of shaping desires to reduce travel: the more travel is enjoyed, the less the desire to reduce it. [Copyright &y& Elsevier]

The article discusses a study on the modes of transportation used for going to work in capital cities in Australia. According to the study, journey to work is essential to peak-hour traffic volumes. The study found that more workers are using cars. ON the other hand, the number of people car-pooling went down. Use of public transportation went down.

Abstract: We present state-space specifications of time series models as a framework to formulate dynamic performance models for transportation facilities, and to estimate them using panel data sets. The framework provides a flexible and rigorous approach to simultaneously capture the effect of serial dependence and of exogenous factors, while controlling for individual heterogeneity when pooling data across the facilities that comprise the panel. Because the information contained in time series and cross-section data are combined in the estimation, the ensuing performance models capture effects that are not identifiable in either pure time series or pure cross-section data. Also, pooling data across facilities leads to improved estimation results. To illustrate the methodology, we consider three classes of models for a panel of asphalt pavements from the AASHO Road Test. The models differ in the assumptions regarding the structure of the underlying mechanisms generating the data sequences. The results indicate that serial dependence is indeed significant, thereby reinforcing the importance of dynamic modeling. We also compare the specifications to assess the poolability of pavement condition data. The results provide evidence that heterogeneity among the facilities is present in the panel. Finally, we highlight features that elude existing performance models developed with static modeling approaches: the ability to estimate maintenance activities as exogenous variables, and the capability of updating forecasts in response to inspections. [Copyright &y& Elsevier]

Abstract: Car clubs have operated on a large scale only since 1987, when the first scheme began in Switzerland, although prior to that there were several smaller-scale projects. Schemes then spread to Germany, Austria and the Netherlands. More recently, car clubs have been set up in the UK, Denmark, Italy, and Sweden, and in Canada and the USA. These clubs have developed (and are still developing) in a number of ways. Some schemes are community-level schemes with only one or two vehicles, while others are national organisations with many thousands of members. And some schemes are run by volunteers and are non-profit making, while others are commercial ventures run by international companies. Despite such diverse beginnings, it is clear that the vast majority of schemes face similar problems in becoming established. One major barrier has been the lack of involvement or support from local and national Government. Given the potential benefits of car clubs to deliver environmental and social improvements to communities, this is somewhat surprising. As experience of car clubs spreads, this situation has begun to change and there are signs that Government attitudes across the world are becoming more enthusiastic to the idea of encouraging car clubs. This paper draws on the results of a state-of-the-art review, based on several face-to-face and telephone interviews, email communications, internet sites and existing literature to identify cases where such a change in attitude has occurred, how various levels of Government have translated this into action, and what lessons could be learnt from each example. [Copyright &y& Elsevier]

Abstract: Non-motorized forms of commuting include bicycling, walking to work and working at home and have the potential for reducing environmental damage. These non-motorized modes are analyzed empirically using US journey to work data. Higher salary income and more expensive housing are associated with greater propensity to work at home, but lower propensity to walk or bicycle. College education is in several cases associated with greater propensity to use non-motorized modes. There are sharp differences in the likelihood of using non-motorized modes across the sub-regions within the metropolitan area. Car ownership, race, gender, and various locational and neighborhood features are shown to affect modal choices regarding non-motorized alternatives, in comparison with car commuting. [Copyright &y& Elsevier]

Home and workplace location choices are closely related. The determinants of these choices operate differently based on an individual's life cycle, particularly with regard to the presence or absence of children. Individuals with children often place value on greenspace and recreational opportunities, while those without children often prefer smaller residential lots and locations with access to services. Existing studies have found that if residential location desires are satisfied, people are less likely to emphasize the importance of job location irrespective of their life stage. Taking a different approach, this study examines home-workplace decisions from a commuting standpoint. Commute durations and personal characteristics are used to analyse individual behavior. The contributions of this work include the finding that environmental characteristics and amenities may explain the connection between commuting behavior and residential location choices. Existing studies have not connected environmental characteristics and commuting behavior. This study also uses various GIS modeling techniques to explore the effects of previously unanalysed variables on residential location decisions. [ABSTRACT FROM AUTHOR]

The article presents the results of a German research project, where recommendations for the synthesis of public transport and car-sharing/car clubs are given. In order to determine effects and factors of success of combined services, the adoption process, the mobility behaviour and customer satisfaction were investigated within the context of model projects in two German cities. The results prove that car-sharing is suitable as a supplement to public transport. [Copyright &y& Elsevier]

The current paper analyses judgements regarding the decision to commute by car versus public transportation in terms of a conflict between immediate self interest and long-term collective interest (i.e. social dilemma). Extending traditional formulations of rational choice theory, the present study revealed that preferences for public transportation (i.e. the presumed cooperative option) in a standard commuting situation were enhanced not only by the belief that public transportation provided a shorter avenge travel time than car (i.e. the presumed noncooperative option), but also by the belief that public transportation was at least as reliable (i.e. an equal or lower variability in travel time compared to car). Moreover, paralleling prior research on experimental social dilemmas, preferences were found to be affected by a pro-social concern--the belief regarding the impact of cars on the level of environmental pollution. Our findings indicated that any combination of two such considerations (i.e. travel time, variability, and impact of cars on pollution) was more effective in promoting public transportation preferences than the sum of their separate effects. Finally, we obtained evidence that commuter preferences were also shaped by individual differences in social value orientations (i.e. preferences for patterns of outcomes for self and others) in that, relative to pro-self commuters, pro-social commuters exhibited greater preference for public transportation. [ABSTRACT FROM AUTHOR]

Statistics on past carpooling trends in the United States are analyzed to determine its future implications for the transportation sector. There is an average of 20% decline in carpooling from 1980 to 1990. Consequently, all the demographic and economic factors should be considered against a backdrop of increasingly dispersed populations and jobs. To solve the decline, organizers of carpooling programs should engage in continuous monitoring of carpooling trends by surveying households that engage in the activity. Researchers should also recognize the obstacles to the successful surveying of the practitioners of carpooling. Finally, carpool promotion programs need a statistical device that honestly conveys what is happening.

No abstract is available for this article. [ABSTRACT FROM AUTHOR]