Visualising where commuting cyclists travel using crowdsourced data

Encouraging more cycling is increasingly seen as an important way to create more sustainable cities and to improve public health. Understanding how cyclists travel and how to encourage cycling requires data; something which has traditionally been lacking. New sources of data are emerging which promise to reveal new insights. In this paper, we use data from the activity tracking app Strava to examine where people in Glasgow cycle and how new forms of data could be utilised to better understand cycling patterns. We propose a method for augmenting the data by comparing the observed link flows to the link flows which would have resulted if people took the shortest route. Comparing these flows gives some expected results, for example, that people like to cycle along the river, as well as some unexpected results, for example, that some routes with cycling infrastructure are avoided by cyclists. This study proposes a practical approach that planners can use for cycling plans with new/emerging cycling data.     

Partial link flow observability in the presence of initial sensors: Solution without path enumeration

Recently, a new methodology (“synergistic sensor location”) has been introduced to efficiently determine all link flows in a road network by using only a subset of the link flow measurements. In this paper, we generalize this previous work by solving the following problem: Suppose that one is only interested in a subset of the link flows, and that certain link flows are known a priori. At a minimum, what link flows are needed to be able to uniquely determine the desired link flows? An algorithm is presented that does not require the need for path enumeration.     

Air express network design based on express path choices – Chinese case study

Due to the shortage of cargo aircraft, Chinese express companies have to provide transportation services with a hybrid method that consists of “rented bellies and self-owned cargo aircraft”. Because the bellies are rented from air passenger companies and because the cargo aircraft are owned by the express companies, it is important for the express companies to use their cargo aircraft as effectively as possible. This paper constructs a bi-level model to optimize the flight transportation network of an express company. The upper model designs the network and allocates the transportation capacity with the objective of minimizing the total transportation cost, and the lower model calculates the link flows in user equilibrium. Data from ShunFeng (SF) Express Company (China) are used to conduct the case study. Using the model outputs, the flows on links and at nodes are analyzed to illustrate the transportation and transshipment situations.     

Bridging the Öresund: potential regional dynamics: Integration of Copenhagen (Denmark) and Malmö–Lund (Sweden) A cross-border project on the European metropolitan level

The construction of the fixed link between Denmark and Sweden will increase the accessibility between South Sweden and East Denmark dramatically. The vision is that the fixed link will span economic, administrative, institutional, technical, cultural and other barriers, and that the two separated urban systems (Greater Copenhagen and Malmö–Lund) can be integrated, opening up for new dynamics. The Öresund (Sound) area has the potential to develop into one functional metropolitan region constituted by flows, markets and terminals. The ambition is to lift Copenhagen to a higher position in the European urban hierarchy by this integration, the instrument being the 16 km long fixed link which will open in the year 2000.     

Business connectivity,air transport and the urban hierarchy: A case study in East Asia

This paper explores the effect of business connectivity between cities on their air traffic connections, and in turn on their place in a region's urban hierarchy. Its focus of attention is East Asia, where economic development is underpinned by a complex set of international flows of trade and investment. Business connectivity is a key part of these flows. The research incorporates a measure of business connections in a regression model that previously relied on GDP per head, population and distance to account for international air links. Results confirm that business connectivity is a more important influence on the level of international air links within East Asia, and plays a major role in explaining the changes in city rank over time. The paper concludes with suggestions that possible incorporation of domestic air travel (itself larger than the intra-regional flows in this region) could enrich the insight of this approach.     

Optimal distance tolls under congestion pricing and continuously distributed value of time

This paper addresses the optimal distance-based toll design problem for cordon-based congestion pricing schemes. The optimal distance tolls are determined by a positive and non-decreasing toll-charge function with respect to the travel distance. Each feasible toll-charge function is evaluated by a probit-based SUE (Stochastic User Equilibrium) problem with elastic demand, asymmetric link travel time functions, and continuously distributed VOT, solved by a convergent Cost Averaging (CA) method. The toll design problem is formulated as a mixed-integer mathematical programming with equilibrium constraints (MPEC) model, which is solved by a Hybrid GA (Genetic Algorithm)–CA method. Finally, the proposed models and algorithms are assessed by two numerical examples.     

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.     

Analysis of bilateral air passenger flows: A non-parametric multivariate adaptive regression spline approach

Gravity models have long served as a framework for analyzing bilateral flows, trade and many other activities. To estimate a gravity model, (parametric) linear regression techniques have been commonly employed to develop the relationship between passenger flows and factors that can significantly influence these flows. This study explores the application of an alternative method, the non-parametric multivariate adaptive regression spline (MARS) technique, to identify the determinants for air passenger flows between pairs of countries. The data of 2006 and 2007 air passenger flows between pairs of countries in the APEC region were collected to develop the MARS models. Results indicate that distance between the countries, annual import value, national per capita income, unemployment rate and consumer price index of the origin country, as well as GDP, annual import value, and consumer price index of the destination country are significant determinants for bilateral air passenger flows.     

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.     

Network based definition of functional regions: A graph theory approach for spatial distribution of traffic flows

Functional regions are autonomous (internally coherent and externally self-contained) spatial structures based on vector data, so-called spatial interactions. Typically, travel-to-work, travel-to-school flows and migrations are analysed by various methods of functional regional taxonomy in order to define functional regions. There is still another type of statistically recorded vector data which has, up to now, rarely been used for this purpose: traffic flows. However, these data differ distinctly from the above mentioned flows. In this paper we pursue two objectives: (i) to define functional transport regions based on a graph theoretic analysis of individual traffic flows, and (ii) to add knowledge to the issue of the self-containment of functional transport regions. The specific nature of transport data compared to the above-mentioned spatial interactions requires a specific methodological approach, which is presented in the paper. The existing graph theoretic procedures do not seem suitable for the definition of functional transport regions due to data specifics. Therefore our analysis is based on a rough analogy to the minimum cut method – we identify minimum flows in a graph representing a transport network. The territory of the Czech Republic is used as the example. Two regional systems are defined (based on 2000 and 2016 data) and compared in time. The paper achieves two main findings. First, the proposed methodological approach allows us to define autonomous functional transport regions, and the means to calculate their self-containment is discussed. Second, functional transport regions in the Czech Republic show unexpected stability over time compared to functional regions based on such spatial interactions as commuting flows.     

Modelling tourist flow association for tourism demand forecasting

The purpose of this study is to examine tourism demand for Singapore from 1995 to 2013 by six major origin countries which belong to three different regions. Unlike prior tourism research, we take into account the dependence relations among the different tourist flows via copula. Copula is a statistical model of dependence and measurement of association. Specifically, we investigate the association between two tourist flows in each region. Based on empirical copula estimation, the Frank function has been identified as the most appropriate to capture the pairwise dependence structures of tourist flows. The copula-based approach combined with econometric models is proposed for tourism demand analysis that can be used to predict tourist arrivals. We apply the copula-ARDL and copula-ECM frameworks to generate joint forecasts of tourist arrivals from three regions. The findings show that the forecast performance of the Frank copula-based model outperforms the benchmark model which corresponds to the independence structure (no association) of tourist flows.     

Braess Paradox of traffic networks with mixed equilibrium behaviors

Under the user equilibrium (UE) behavior assumption, the Braess Paradox (BP) and its variations have been well investigated. However, users do not always follow the UE behavior. In reality, there are likely quiet a few non-collaborative Cournot–Nash (CN) players coexisting with UE players in the common traffic network. Users in a CN player are completely collaborative to minimize their total travel cost and users subordinating to different players are perfectly competitive. Considering both UE and CN players in the congested network, it remains unclear that under what conditions the BP will occur. In this paper, the BP occurrence conditions under the UE–CN mixed equilibrium are firstly investigated using the classical Braess network with linear link cost function. Then, the BP conditions are studied to the ordinary grid network with nonlinear link cost function. It is shown that the BP occurrence in the conventional Braess network depends upon the link travel time function parameters and the demand level of users controlled by UE/CN players, and the BP occurs in the grid network only for certain demand combinations of users under one UE player and two CN players.     

Gravitational force exerted by Brazilian tourist destinations on foreign air travelers

This article analyses the context of international tourist flows by air and tourism in Brazil, by applying the principles of the gravity model. The study includes 13 Brazilian international airports that served 108 origin-destination pairs, which accounted for 80.14% of the total tourist flows by air in 2012. In the statistical analysis applied, the dependent variable Ft is the tourist flow between the country of origin and the Brazilian state of destination. To approximate an explanatory equation, we formulated a linear function that was able to support, in 31.7% of the cases, the dependence of the international tourist flows with the variables considered in the linear regression performed. The conclusion is that the assumptions considered in this study only partially explain the gravitational force exerted by Brazilian tourist destinations, so there is a need to refine the model by including other variables that can influence the flows by air of international tourists.     

Location optimisation method for fast-charging stations along national roads

Limited range of electric vehicles is still a huge barrier compared to conventional vehicles. A well-established charging station network, which is derived from users' charging demand, facilitates the spread of electric vehicles and lessens the range anxiety. Several methods have been developed for locating fast-charging stations along national roads in Europe according to the given objective function. In this paper, an arc-based location optimisation method realized by using a geographic information system and greedy algorithm is presented. An ‘oil stain’ deployment strategy is used to achieve even coverage with the minimum number of fast-charging stations along the roads. Several demographic, neighbourhood, and transport-related attributes, as well as the available services that influence the utilization of a fast-charging station, have been identified and their effects have been revealed in a systematic approach. The developed multi-criteria decision-making method has been applied to evaluate the rest areas along motorways and main roads and to propose deployment locations for fast-charging stations. The method was applied for Hungary as a case study and validated using real origin-destination (O-D) data. By the application of the locating method, the user can specify a network character by geographic parameters. The method can be especially beneficial if the O-D flows are unknown. Furthermore, the even distribution of the stations contributes to the high utilization of the fast-charging stations.     

Connecting African urban areas: airline networks and intra-Sub-Saharan trade

Despite efforts to enhance the efficiency of the African air transportation sector through such actions the Yamoussoukro Decision, African represents less than 2% of the world’s air passenger kilometers. This is despite the fact that air transportation can act as a means of transporting traded goods directly (including the individuals that are the “product” of tourism) and provide complementary services of labor mobility for those engaged in the production of more bulky goods that are shipped by land and maritime modes. We examine the network of intra-Sub-Saharan African airline connections to highlight the differential access enjoyed by the region’s largest cities. Second, we develop a quantitative framework linking the availability of air connections to the main international trade flows in sub-Sahara Africa. Our findings suggest that, although there is a positive link between air transportation and economic development in Africa, the multilateral efforts at reducing institutional impediments to more open aviation markets have not produced significant results.     

Congestion analysis of waterborne, containerized imports from Asia to the United States

A queuing model is introduced for estimating container flow times through port terminals as a function of infrastructure, staffing, and import volume. The model is statistically calibrated on industry data. Flow-time estimates of the model are aggregated with estimates from models previously developed for rail networks to develop estimates of the total container flow times from West Coast ports to inland distribution centers. Integrated with a supply-chain optimization model, the queuing formulas are used to predict import flows by port and landside channel in scenarios of total import growth, varying all-water rates, and a higher import share for nation-wide importers.     

An inventory-based simulation model for annual-to-daily temporal freight assignment

In the aggregate freight demand modeling literature, temporal assignment (annual to daily flows) is often oversimplified or neglected altogether. Unlike passenger flows, freight flows over the course of a year are not uniform and can vary significantly as the result of trade-offs between inventory and transportation cost management. We introduce the first temporal assignment model that explicitly considers these trade-offs for aggregate freight forecasting. A two-stage model is proposed that first decomposes aggregate annual zonal flows to firm group annual flows using a supply chain network model, which are then temporally assigned by simulating purchase order transactions throughout supply chains. Lot sizes are estimated with an Economic Order Quantity (EOQ) model and calibrated with monthly inventory data. The result is an aggregate-disaggregate-aggregate model that fits into aggregate freight forecasting models but makes use of more disaggregate logistical data. The model is illustrated with a simple replicable example, followed by a case study conducted with California statewide data to break out the distributed zonal flows into average daily volumes for network assignment. Calibration results using 2007 IMPLAN data showed a median percentage difference of simulated annual flows from FAF³ data of 2.38%, and a median percentage difference of simulated inventories from IMPLAN data of 4.85%, which suggests an excellent fit. Empirical validation results showed the model outperforms fixed factor approaches in mean value accuracy by 15–31%.     

Satellite terminals: a local solution to hub congestion?

Transport hubs are important generators of freight traffic both between and within metropolitan areas. The concentration of traffic places pressure on the terminals to expand their sites to cope with the business. At the same time the spatial spread of flows is becoming more extensive, impacting ever more severely on local communities. This paper explores some of the questions involving the need for terminals to continue expanding sites that are often in zones of intense environmental and land use conflict. It goes on to consider an alternative comprising satellite facilities, with the consequential dispersal of some transfer functions to sites that may be some distance from the main hubs themselves.     

Operational efficiency analysis of Beijing multi-airport terminal airspace

Multi-airport systems are growing in number and size globally, despite being afflicted by known inefficiencies due to the interferences between the flows of neighbouring airports. A macroscopic empirical approach is proposed in this paper to estimate the capacity penalties and demonstrated by a numerical case study for Beijing, which is projected to become one of the busiest metroplexes in Asia. The Pareto envelopes of the theoretical and observed peak hour capacities are statistically analysed to quantify the penalties in a comparable metroplex and are subsequently modulated by a sigmoid correlation function. The analysis predicts the practical capacity of Daxing, the penalty incurred by the pre-existing Capital airport and by the total multi-airport system. Various findings are drawn and discussed, highlighting the needs for further research.     

A heuristic approach to logistics network design for end-of-lease computer products recovery

This paper discusses the logistics network design for end-of-lease computer products recovery by developing a deterministic programming model for systematically managing forward and reverse logistics flows. Due to the complexity of such network design problem, a two-stage heuristic approach is developed to decompose the integrated design of the distribution networks into a location–allocation problem and a revised network flow problem. The applicability of the proposed method is illustrated in a numerical study. Computational experiments demonstrate that high-quality solutions are obtained while modest computational overheads are incurred.