Tradable travel credits for congestion management with heterogeneous users

This paper carries on the recent work of Yang and Wang (2011) on tradable credit schemes by considering heterogeneous users with different value of time (VOT). Given a tradable credit scheme, the user equilibrium (UE) and market equilibrium (ME) conditions with heterogeneous users are formulated into a variational inequalities (VI) problem. Sufficient conditions for uniqueness of the aggregate UE link flows and then the ME credit price are established. Appropriate tradable credit schemes are developed to decentralize system optimal and Pareto-improving network flow patterns. Extension is made to the elastic demand case.     

Tradable credit schemes for managing bottleneck congestion and modal split with heterogeneous users

This paper examines the efficiency of a tradable travel credit scheme for managing bottleneck congestion and modal split in a competitive highway/transit network with continuous heterogeneity in the individuals’ value of time. Each user is initially endowed with a certain amount of travel credits and can sell or buy additional credits in a free trading market. Time-dependent credit charge is implemented only for usage of the road bottleneck. We show that both the modal split and credit charge at equilibrium are unique, and the scheme is always Pareto-improving when the system optimum is achieved.     

Tradable credit scheme for mobility management considering travelers’ loss aversion

Under a given tradable credit scheme, travelers’ loss aversion behavior for credit charging during the route choice process is studied. A disutility function of loss aversion is applied to approach travelers’ different attitudes towards credit loss and gain, and the transaction costs of buying and selling credits are also incorporated in the function. The user equilibrium (UE) and market equilibrium (ME) conditions considering loss aversion effects are formulated into a variational inequality (VI) problem. Analyses demonstrate that the system optimum (SO) credit scheme does not always exist. A proposition is further presented to guarantee its existence.     

Transportation and recreation: a case study of visitors driving for pleasure at Acadia National Park

Automobiles and roads are as much of a way of experiencing national parks as they are a means of conveyance. This study examines experiential aspects of transportation on Acadia National Park’s primary scenic road – Ocean Drive. Interviews with vehicle-based road users were conducted to identify indicators to measure and manage experiential quality on Ocean Drive. Also, a survey was conducted to make comparisons with important variables identified on “transportation-only” urban roads. Results suggest that (1) Ocean Drive is important to park visitors’ experience; (2) experiential indicators for Ocean Drive include vehicle crowding, scenery, and travel freedom/convenience; and (3) experiential aspects of transportation on scenic roads in parks may differ substantially from urban roads. Study findings suggest a need to deliberately and thoughtfully plan and manage for quality recreational experiences on roads in national parks and related areas.     

Modeling AADT on local functionally classified roads using land use,road density,and nearest nonlocal road data

The focus of this research is to model the influence of road, socioeconomic, and land-use characteristics on local road annual average daily traffic (AADT) and assess the model's predictability in non-covered location AADT estimation. Traditional ordinary least square (OLS) regression and geographically weighted regression (GWR) methods were explored to estimate AADT on local roads. Ten spatially distributed counties were considered for county-level analysis and modeling. The results indicate that road density, AADT at the nearest nonlocal road, and land use variables have a significant influence on local road AADT. The GWR model is found to be better at estimating the AADT than the OLS regression model. The developed county-level models were used for estimating AADT at non-covered locations in each county. The methodology, findings, and the AADT estimates at non-covered locations can be used to plan, design, build, and maintain the local roads in addition to meeting reporting requirements. The prediction error is found to be higher at urban areas and in counties with a smaller number of local road traffic count stations. Recommendations are made to account for influencing factors and enhance the local road count-based AADT sampling methodology.     

Multi-period equilibrium modeling planning framework for tradable credit schemes

This study proposes the concept of multi-period tradable credit scheme (TCS) for a planning context. In it, travelers determine their actions in terms of consumption or sale of credits in the current period or transfer to future periods. In the first scheme, travelers can transfer credits to future periods without penalty. In the second scheme, the effects of two regulatory instruments are investigated on the market behavior. Study insights suggest that a multi-period TCS dampens credit price volatility. It allows the central authority to develop TCSs with stable credit prices in which travelers can hedge against potential monetary losses.     

Bounding the inefficiency of atomic splittable selfish traffic equilibria with elastic demands

We determine the exact upper bound of the inefficiency of atomic splittable selfish traffic equilibria with elastic travel demand with and without road pricing. In the previous results, only pseudo-approximation bound were obtained for this case. By comparison, we also conclude that the traffic equilibrium with elastic demand may be worse than the corresponding fixed demand case, which implying that the demands’ elastic can have a negative effect on the quality of equilibrium solutions. Finally, we propose a road pricing mechanism. We prove that there are optimal tolls in general network, atomic players and elastic travel demand setting.     

A hybrid implementation mechanism of tradable network permits system which obviates path enumeration: An auction mechanism with day-to-day capacity control

Akamatsu, 2007a, Akamatsu, 2007b proposed a new dynamic traffic congestion control scheme called tradable network permits, and demonstrated its efficiency properties for general road networks. To implement tradable permit markets, this paper proposes a novel auction mechanism with capacity control. This mechanism employs an evolutionary approach to achieve a dynamic system optimal allocation of network permits in a computationally efficient manner. We prove that the proposed mechanism has the following desirable properties: (i) truthful bidding is a dominant strategy for each user on each day and (ii) the permit allocation pattern under the mechanism converges to a dynamic system optimal allocation pattern.     

Annual average daily traffic estimation in England and Wales: An application of clustering and regression modelling

Collection of Annual Average Daily Traffic (AADT) is of major importance for a number of applications in road transport urban and environmental studies. However, traffic measurements are undertaken only for a part of the road network with minor roads usually excluded. This paper suggests a methodology to estimate AADT in England and Wales applicable across the full road network, so that traffic for both major and minor roads can be approximated. This is achieved by consolidating clustering and regression modelling and using a comprehensive set of variables related to roadway, socioeconomic and land use characteristics. The methodological output reveals traffic patterns across urban and rural areas as well as produces accurate results for all road classes. Support Vector Regression (SVR) and Random Forest (RF) are found to outperform the traditional Linear Regression, although the findings suggest that data clustering is key for significant reduction in prediction errors.     

Investigating the associations between road network structure and non-motorist accidents

Road networks channel traffic flow and can impact the volume and proximity of walking and bicycling. Therefore, the structure of road networks—the pattern by which roads are connected—can affect the safety of non-motorized road users. To understand the impact of roads’ structural features on pedestrian and bicyclist safety, this study analyzes the associations between road network structure and non-motorist-involved crashes using data from 321 census tracts in Alameda County, California. Average geodesic distance, network betweenness centrality, and an overall clustering coefficient were calculated to quantify the structure of road networks. Three statistical models were developed using the geographically weighted regression (GWR) technique for the three structural factors, in addition to other zonal factors including traffic behavior, land use, transportation facility, and demographic features. The results indicate that longer average geodesic distance, higher network betweenness centrality, and a larger overall clustering coefficient were related to fewer non-motorist-involved accidents. Thus, results suggest that: (1) if a network is more highly centered on major roads, there will be fewer non-motorist-involved crashes; (2) a network with a greater average number of intersections on the shortest path connecting each pair of roads tends to experience fewer crashes involving pedestrians and bicyclists; and (3) the more clustered road networks are into several sub-core networks, the lower the non-motorist crash count. The three structural measurements can reflect the configuration of a network so that it can be used in other network analyses. More information about the types of road network structures that are conducive to non-motorist traffic safety can help to guide the design of new networks and the retrofitting of existing networks. The estimation results of GWR models explain the spatial heterogeneity of correlations between explanatory factors and non-motorist crashes, which can support regional agencies in establishing local safety policies.     

Route choice and residential environment: introducing liveability requirements in navigation systems in Flanders

Vehicle route planning and navigation systems aim to provide the most beneficial routes to their users while disregarding the impact on the liveability of the surrounding residential areas. Therefore, future integration of route choice behaviour by route planners and measures to improve liveability and safety standards should be pursued. The Spatial Plan for Flanders, which is the overarching spatial policy plan in the northern part of Belgium, determines a system of road categories aimed at optimising the liveability of sensitive areas, such as residential neighbourhoods or school precincts, without jeopardizing accessibility. This paper examines to what extent routes proposed by commercial route planners differ from more socially desirable routes that are guided by the policy principles of road categorisation in Flanders as proposed by the plan. Results show that commercial route-planners’ routes choose more often roads of the lowest category than socially acceptable. However, for some of the assessed connections, the socially desired alternative is a feasible route as well, which is not excessively increasing time consumption or distance travelled. It is concluded that the implementation of the prevailing road categorisation system in Flanders in routing algorithms has the potential to promote more sustainable route choices, while infrastructural measures that discourage cut-through traffic may help materialising the categorisation system.     

Modelling the impact of alternative pricing policies on an urban multimodal traffic corridor

This paper investigates the effects of alternative or joint schemes of road pricing and parking pricing to verify if private behaviour in operating parking facilities, road tolling and transit systems can lead to profitable results in the private sector and for public welfare. The evaluation is carried out using an idealised urban multimodal traffic corridor with some numerical examples that show the effects of different pricing policies. A Deterministic User Equilibrium assignment procedure is used to calculate certain performance indicators such as user travel costs, social costs and private profit. The results show that the system is highly sensitive to pricing policy and that a proper joint pricing of park-and-ride facilities, city centre parking and road tolls can be developed to simultaneously attain good private and social benefits.     

Decentralizing Pareto-efficient network flow/speed patterns with hybrid schemes of speed limit and road pricing

This paper examines the potential of hybrid schemes of speed limit and road pricing for decentralizing Pareto-efficient flow/speed patterns that minimize total travel time and total emissions simultaneously. Both link flows and speeds are treated as independent variables in our bi-objective formulation. The resulting Pareto frontier is thus weakly dominant to that in previous literature. For any such favorable Pareto-efficient flow and speed pattern, we establish the existence of hybrid schemes of speed limits and non-negative/revenue-neutral tolls, whose set of user equilibrium (UE) solutions contains the Pareto-efficient one, and provide sufficient conditions under which the Pareto-efficient solution can be certainly obtained.     

Context sensitive multimodal road planning: a case study in Cape Town, South Africa

Road planning practice relies almost exclusively on parameters related to traffic factors, such as private vehicle speeds and volumes. In many developing countries the requirements for public transport and non-motorised transport are not explicitly integrated into the planning process, despite the fact that these form the primary mode of transport for the majority of the population. This affects the mobility opportunities for these sectors of the population and contributes to poor road safety, especially with regards to pedestrians. The research outlined in the paper posits that, in order to assess the usage and needs of the road holistically, other factors related to the adjacent land uses, socio-economic characteristics of the population the road serves, and the environmental context within which the road is located, factors heavily in how the road is used and should, therefore, be considered within the planning process. The paper describes a methodology to include these factors in the planning of roads. The method attempts to prioritise amongst the five primary road based modes (public transport, car, freight, walking and cycling) based upon a combination of traffic and non-traffic factors. The method employed uses a geographic information system (GIS) based spatial multiple criteria evaluation (SMCE) model with inputs from widely available data sources such as census, household travel surveys, land use and environmental data to arrive at solutions for modal priorities. A case study is conducted along an arterial route in Cape Town, South Africa, providing infrastructure planning recommendations and audit possibilities for the future. Since weighting is an important driver in the SMCE process, a sensitivity analysis is conducted to investigate the effect of alternative weighting schemes on the outputs from the method.     

Hierarchical system of road networks with inward, outward, and through traffic

This paper formulates a continuous model of a grid road network for determining the optimal hierarchical system of road networks. The hierarchical system is represented as the proportions of area taken up by roads at each level of the hierarchy. The objective is to derive the optimal ratio of road areas that minimizes the total travel time. The model explicitly incorporates inward, outward, and through traffic as well as inner traffic to examine how traffic composition affects the optimal ratio of road areas. The result reveals that the optimal ratio of major arterial roads increases with inward, outward and through traffic.     

The hierarchy of roads, the locality of traffic, and governance

This study investigates the use of road networks both within and outside of home jurisdictions (city (or town) and county of residence) by analyzing GPS data collected in the Minneapolis—Saint Paul metropolitan area. The study tracked volunteers' travel behavior to determine which roads (and thus which class of roads) users chose to accommodate their travel needs. More than half of the travel on county roads and city streets occur outside of one's home city, but most travel is within one's home county. The average share of travel distance in the home county is more than 70% for both county and city streets. The high share, which does not account for non-residents destined for the county to work or shop, e.g., implies that the free rider problem on city and county streets at the county level is minimal. Of particular concern is travel on city roads in cities other than one's own. To the extent that this is to go to a destination in that city, that travel is also local. However, because city and county roads are typically funded by those jurisdictions from land-based sources such as property taxes, through trips with neither end in the city through which they are traveling are in a very real sense “free riders”, and pose a problem. With growing trip lengths and emerging economies of scale in road management, it may be appropriate to consider moving more roads from township, town, or city level to the county level of government.     

Regional road development,rural and urban poverty: Evidence from China

The study estimates the impact of road investments on overall economic growth, rural and urban growth, and rural and urban poverty reduction. To achieve these goals, an econometric model that captures the different channels through which road investment impacts growth and poverty is developed and estimated using provincial-level data for 1982–1999 in China. Low-grade (mostly rural) roads have benefit/cost ratios for national GDP that are about four times larger than the benefit/cost ratios for high-grade roads. In terms of poverty reduction, low-grade roads raise far more rural and urban poor above the poverty line per yuan invested than do high-grade roads. Another significant finding of the study is the trade-off between growth and poverty reduction when investing in different parts of China. Road investments yield their highest economic returns in the eastern and central regions of China, while their contributions to poverty reduction are greatest in western China (especially the southwest region).     

Athens 2004 Olympic Games' Transportation Plan: a missed opportunity for Strategic Environmental Assessment (SEA) integration?

During the 1990s, a considerable debate on the integration of Strategic Environmental Assessment (SEA) with the policy, plan and programming process took place among scholars throughout the world. This debate is relevant today, especially in the context of Sustainable Development (SD) as it is maintained that the integration of environmental concerns in policy, plan and programme (PPP) making, is a step towards sustainable planning practices. This is also the rationale behind the recent enactment of the European Union (EU) Directive on the `assessment of the effects of certain plans and programmes on the environment' (or `SEA Directive') which requires that following the 21st July 2004, all member states' authorities preparing certain formal plans or programmes should undertake SEAs by preparing an environmental report describing the potential effects of plans and programmes upon the environment. This paper applies an integrative SEA/PPP framework, to the transport planning process of a major international athletic event: the Athens 2004 Olympic Games. It was found that despite the lack of a formal SEA in place, there are positive signs for its future integration in similar studies in Greece. Furthermore, it is recommended through comparison with other SEAs for Olympic Games, that weight should be given to the co-ordination of the common stages of the PPP and SEA processes, if SEA practice is to be encouraged in countries with underdeveloped SEA systems such as Greece.     

Efficiency of the plate-number-based traffic rationing in general networks

Road space rationing based on vehicle plate numbers restricts vehicle access to a network based upon the license number on pre-established days. It has been used in some large cities especially when there are some major events. This paper analyzes the efficiency of road space rationing schemes by establishing the bounds of the reduction in the system cost associated with the restricted flow pattern at user equilibrium in comparison with the system cost at the original user equilibrium. The bounds are established under the general traffic equilibrium model formulated as variational inequalities and illustrated with a simple example.     

The safety impact of land use changes resulting from bypass road constructions

This paper analyzes the effect of bypass construction on road safety, specifically crash rates on bypass segments and in bypassed communities. It further investigates the effect of bypass construction on those communities’ economic development through changes in the number and spatial distribution of businesses and residential development, and examines whether these changes affect the road-safety level. Finally, it evaluates the effect on road safety of various traffic arrangements implemented in such communities. Drawing on an extensive data collection, the study focuses on Arab cities in the Galilee region of Israel, using cross-sectional and longitudinal analysis.The results show that bypass construction does not necessarily reduce overall crash frequencies or crash rates. It merely shifts road crashes from the highways (the bypass roads) to inner roads (bypassed) and from there to local traffic, with no significant reduction. The findings indicate a large variance in the effects of bypass constructions on safety.