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l Performance of mixtures consisting R1234yf, R170, R41 and R1132a were investigated within a three-stage ACR. l All alternatives presented promising energy results and can be recommended to replace R23. l The isobaric 3D and the isothermal-isobaric ternary VLE diagrams were presented. l R1234yf/R23/R14 (0.59/0.24/0.17) offers the maximum COP and exergy efficiency of 0.614 and 26.15%. l R1234yf/R41/R14 (0.64/0.17/0.19) is suggested as a promising alternative refrigerant at -100 °C. In order to seek promising refrigerants for vapor compression refrigeration system to obtain ultra-low temperatures down to -100 °C, and to determine whether the low-GWP refrigerants, R41, R170 and R1132a, are suitable substitutes for R23, this study conducted a comprehensive comparative analysis on the cycle characteristics of a three-stage auto-cascade refrigeration (ACR) system using R1234yf/R23/R14, R1234yf/R41/R14, R1234yf/R170/R14 and R1234yf/R1132a/R14. The system performances, including cooling capacity, coefficient of performance (COP), evaporation temperature, compressor discharge temperature, exergy destruction and efficiency were investigated with various compositions and vapor qualities. Results show that R41, R170 and R1132a can all be recommended to replace R23, and the alternatives present promising thermodynamic properties in theoretical simulations. Under the same operation conditions, the cooling capacity of the R1234yf/R41/R14 system is the largest, while the maximum COP and exergy efficiency occur in the R1234yf/R23/R14 system. Considering the energy shortage and environmental pollution issues, R1234yf/R41/R14 with the mass fraction of 0.64/0.17/0.19, COP of 0.2713, and exergy efficiency of 13.91% performs better and hence can be suggested as an alternative refrigerant for the three-stage ACR operating at -100 °C. The largest exergy destruction component occurs in the compressor, followed by the air-cooled condenser and expansion valve, on which future optimization work can be carried out. The results provide a basic theoretical analysis of the selection and replacement of refrigerant in three-stage ACR. [ABSTRACT FROM AUTHOR]

This paper is the first to empirically compare the impact of fuel price on ridership of taxicabs and transportation network companies (TNCs) like Uber and Lyft. We build a theoretical model of the car service market to demonstrate how drivers under the two systems may have different reactions to fuel prices. Although all drivers pay for their own gasoline, TNC drivers have more flexibility in reducing their supply when operating costs are relatively higher. Due to greater regulation, taxi drivers are more fixed in their supply but receive a "rigidity dividend" from paying greater gas costs while profiting from the reduced competition when TNC drivers leave the market. Through ordinary least squares and seemingly unrelated regression estimation, we find that a 1-day 1% increase of fuel prices in New York City is associated with a 0.367% to 0.486% decrease in trips from TNCs, while the quantity of taxi trips will slightly increase by 0.033% to 0.088%. Empirical results additionally show a diminishing marginal effect for the fuel price elasticity of TNC trips. [ABSTRACT FROM AUTHOR]

Public transit accounts for 1 percent of US passenger miles traveled but attracts strong public support. Using a simple choice model, we predict that transit riders are likely to be individuals who commute along routes with severe roadway delays. These individuals' choices thus have high marginal impacts on congestion. We test this prediction with data from a strike in 2003 by Los Angeles transit workers. Estimating a regression discontinuity design, we find that average highway delay increases 47 percent when transit service ceases. We find that the net benefits of transit systems appear to be much larger than previously believed. (JEL H76, J52, L92, R41).

Heavier vehicles are safer for their own occupants but more hazardous for other vehicles. Simple theory thus suggests that an unregulated vehicle fleet is inefficiently heavy. Using three separate identification strategies we show that, controlling for own-vehicle weight, being hit by a vehicle that is 1000 pounds heavier generates a 40-50% increase in fatality risk. These results imply a total accidentrelated externality that exceeds the estimated social cost of US carbon emissions and is equivalent to a gas tax of $0.97 per gallon ($136 billion annually). We consider two policies for internalizing this external cost, a weight-varying mileage tax and a gas tax, and find that they are similar for most vehicles. The findings suggest that European gas taxes may be much closer to optimal levels than the US gas tax. © The Author 2013. Published by Oxford University Press on behalf of The Review of Economic Studies Limited.

Since “Belt and Road initiative” (BRI) has been launched, the major volume of academic studies focus on the consideration of Eurasian land and maritime transport routes. Experts on Chinese foreign policy and geopolitical strategy emphasize possible positive and negative aspects of the initiative for the states involved. The business and political circles from Eastern Baltic Sea region are looking for possible ways to attract cargo to its ports. Yet, the possible transformations of Chinese foreign trade flows in the context of BRI are now under academic consideration. We focus on the evaluation of ports’ possibilities to handle Chinese cargo. The key issues of our study include the choice of cargo transportation routes and opportunities to attract Chinese investment to expand port and logistics infrastructure. The methodology of the research is based on statistical data analysis for the further comparison of transport routes. Our empirical results demonstrate that Eastern Baltic Sea ports can attract little part of Chinese trade flows.

Aim/purpose – The main objective of the paper is to explore mobility choices of Generation Y in Poland to check if they can be translated into guidelines for the development of mobility services.

Many healthcare report cards provide information to consumers but do not represent a constraint on the behavior of healthcare providers. This is not the case with the report cards utilized in kidney transplantation. These report cards became more salient and binding, with additional oversight, in 2007 under the Centers for Medicare and Medicaid Services Conditions of Participation. This research investigates whether the additional oversight based on report card outcomes influences patient selection via waiting-list registrations at transplant centers that meet regulatory standards. Using data from a national registry of kidney transplant candidates from 2003 through 2010, we apply a before-and-after estimation strategy that isolates the impact of a binding report card. A sorting equilibrium model is employed to account for center-level heterogeneity and the presence of congestion/agglomeration effects and the results are compared to a conditional logit specification. Our results indicate that patient waiting-list registrations change in response to the quality information similarly on average if there is additional regulation or not. We also find evidence of congestion effects when spatial choice sets are smaller: new patient registrations are less likely to occur at a center with a long waiting list when fewer options are available. [ABSTRACT FROM AUTHOR]

5G attains the role of a GPT for an open set of downstream IoT applications in various network industries and within the app economy more generally. Traditionally, sector coupling has been a rather narrow concept focusing on the horizontal synergies of urban system integration in terms of transport, energy, and waste systems, or else the creation of new intermodal markets. The transition toward 5G has fundamentally changed the framing of sector coupling in network industries by underscoring the relevance of differentiating between horizontal and vertical sector coupling. Due to the fixed mobile convergence and the large open set of complementary use cases, 5G has taken on the characteristics of a generalized purpose technology (GPT) in its role as the enabler of a large variety of smart network applications. Due to this vertical relationship, characterized by pervasiveness and innovational complementarities between upstream 5G networks and downstream application sectors, vertical sector coupling between the provider of an upstream GPT and different downstream application industries has acquired particular relevance. In contrast to horizontal sector coupling among different application sectors, the driver of vertical sector coupling is that each of the heterogeneous application sectors requires a critical input from the upstream 5G network provider and combines this with its own downstream technology. Of particular relevance for vertical sector coupling are the innovational complementarities between upstream GPT and downstream application sectors. The focus on vertical sector coupling also has important policy implications. Although the evolution of 5G networks strongly depends on the entrepreneurial, market-driven activities of broadband network operators and application service providers, the future of 5G as a GPT is heavily contingent on the role of frequency management authorities and European regulatory policy with regard to data privacy and security regulations. [ABSTRACT FROM AUTHOR]

Heavier vehicles are safer for their own occupants but more hazardous for other vehicles. Simple theory thus suggests that an unregulated vehicle fleet is inefficiently heavy. Using three separate identification strategies we show that, controlling for own-vehicle weight, being hit by a vehicle that is 1000 pounds heavier generates a 40-50% increase in fatality risk. These results imply a total accidentrelated externality that exceeds the estimated social cost of US carbon emissions and is equivalent to a gas tax of $0.97 per gallon ($136 billion annually). We consider two policies for internalizing this external cost, a weight-varying mileage tax and a gas tax, and find that they are similar for most vehicles. The findings suggest that European gas taxes may be much closer to optimal levels than the US gas tax. © The Author 2013. Published by Oxford University Press on behalf of The Review of Economic Studies Limited.

I study battery electric vehicle (BEV) usage and ownership characteristics with fundamental implications for the electrification of passenger transportation. Using data covering the entire BEV population in New York, I quantify BEV mileage and electricity consumption and highlight the important role of vehicle utilization in contributing to real-world pollution damages and their spatial variation. I then study the factors influencing how much BEVs are driven with a focus on estimating the electricity price elasticity of BEV mileage. Understanding how drivers respond to these changes in operating costs may help align the social and private costs of BEV driving and illustrates how electric utilities may affect transportation outcomes in the future. I find a 10% increase in residential electricity prices reduces mileage by 1%, but responsiveness falls as public charging stations-where prices are often decoupled from electricity costs-become available., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

We employ a Bayesian Vector Autoregressive methodology, to counter the issue of data availability, and explore the relationship between seaborne commodity trade and freight rates. Our results show three important insights: first and foremost, the quantity of seaborne commodity trade has a strong impact on the Baltic Dry Index and the Baltic Dirty Tanker Index, but not on the Baltic Clean Tanker Index, most likely due to the fact that clean tankers can simultaneously operate both in the clean and the dirty sectors. Second, a shock in the price of brent oil has the expected positive response from the Baltic Dry Index, while its relationship with the Baltic Clean Tanker Index and the Baltic Dirty Tanker Index is negative as, in this case, tanker vessels can operate as floating storage units. Third, a relationship between the freight indices appears to hold as a change in one could spill over to the other.

The present study develops a spatial unconditional quantile regression by extending Firpo et al.'s (Econometrica 77:953–973, 2009) unconditional quantile regression and empirically investigates the determinants of parking prices at different quantiles of prices in Japan. The empirical results suggest that spatial competition in terms of unit price and the unit time play important roles in determining parking prices. On the contrary, price is unaffected by demand, approximated by adopting several employment density variables and aggregated people flow data obtained from cell phones. Besides, significant differences exist among the factors that affect parking prices during the day and at night as well as among the unconditional quantiles. [ABSTRACT FROM AUTHOR]

In transit modeling, access and egress conditions are often overlooked. The most common modeling technique of these conditions relies on the use of centroid connectors. This definition often uses the geographic position of zone centroids and sets constraints on the maximum number and length of connectors. This definition is subject to spatial aggregation issues and has already been proven to bias car assignment outcomes. The impact on transit assignment outcomes has not yet been demonstrated. The current paper investigates the statistical impact of connectors on transit assignment outcomes in an urban model of Lyon in France. Findings suggest that transit ridership, total passenger-kilometers and transit transfers are dependent on the definition of centroid connectors. Setting arbitrary values for the maximum number and length of connectors statistically affects transit results. The pattern and magnitude of this impact vary, however, between transit modes. The bus and rapid bus systems have been shown to be more sensitive towards the definition of connectors than the subway and the light rail systems. These findings question, to a certain extent, the validity and reliability of transit modeling outcomes. [ABSTRACT FROM AUTHOR]

The inaccuracy of traffic forecasts has long stood as a central research theme in the field of infrastructure and transportation studies. The literature presents several motives for this phenomenon, ranging from a political bias, insufficient technical preparation, changing urban patterns, and economic dynamics. Uncertainty due to the inaccuracy of forecasts can have a profound impact on the infrastructure development process, right through from the preliminary studies up until the operation and re-negotiation of contracts (in cases when projects are developed using a concessions model). This paper provides an extensive systematic review of forecast inaccuracy in roads and railways projects (analyzing trends, causes, and results). The research found that: (1) forecasts in rail projects are generally more optimistic than in road projects; (2) over the last couple of decades the accuracy of forecasts has not improved significantly, and; (3) there has been a generalized ramp-up effect in forecasts. [ABSTRACT FROM AUTHOR]

Public infrastructure procurement involves significant incentive problems because contracts are often incomplete. Output- and performance-based road contract (OPRC) is an innovative contractual scheme that has been developed in the road sector. Unlike traditional input-based procurement methods, contractors can freely design, invest in, and maintain roads to deliver an agreed level of road functionality, which helps to ensure the sustainability of road maintenance. Using data from Zambia, this paper shows that major reconstruction works under OPRC arrangements are effective at increasing agricultural production. In particular, small-scale farmers who currently use only a few advanced inputs, can benefit from improved connectivity from improved roads. The results also indicate the possibility of improved accessibility, which allows new economic opportunities for farmers who currently do not participate in market transactions. [ABSTRACT FROM AUTHOR]

Robust road transportation networks are essential to facilitate truck movements between regions. Disruptions along certain road links could degrade the network's robustness and curtail regional commerce. A network is considered robust if the network-wide travel cost does not change significantly before and after disruptions. The network robustness index (NRI) is a well-known measure for examining the effect of reduced capacity on one or more links. It has been mainly applied to urban networks and passenger trips. In this paper, the NRI is applied to assess the robustness of the Ontario-wide truck network. Truck flows between the 49 census divisions within Ontario and 25 external zones for the year 2012 are modeled on the network of 35,254 road links and 14,444 associated nodes. Several scenarios of incrementally reduced capacity on specific critical links are devised and simulated. The NRI is calculated for each scenario to identify the level of network robustness. The locational effects of the capacity reductions were explored with the help of maps to assess the change in traffic volumes of the simulated scenarios relative to the base case. As expected, traffic diffuses or shifts to neighboring links when capacities are reduced. These results can be useful in infrastructure planning and the design of alternative routes to minimize the negative impact on traffic flows when disruptions occur. [ABSTRACT FROM AUTHOR]

Recent interests in transit services have captured attention of experts on the monitoring of public transport quality. Previous research focused on relevant models and methods to monitor the quality of transit services and showed where and when different service quality levels occur. However, there was little attention to detect objectively a pool of key quality indicators (KQI) to be monitored, from a large set. This paper covers this gap by the proposal of an integrated approach, which identifies a long list of KQI, defines their properties, involves experts to elicit judgments for each KQI, evaluates the long list, and points out the most promising set. This integrated approach is demonstrated with an application based on an international survey and a Monte Carlo simulation method. Moreover, a restricted and relevant set of 9 overlapping KQI is derived by linking these results with those obtained from two different approaches. [ABSTRACT FROM AUTHOR]

Public transport origin–destination (OD) estimation based on smartcard data has increasingly been used for transit network planning, passengers' behaviour analyses and network demand forecasting. While various OD estimation methods using the trip-chaining approach have been developed in recent years, the validity of these estimation methods has not extensively been investigated. This study examines the errors in OD estimation caused by inaccurate inference of alighting stops, to improve the accuracy of the existing trip-chaining algorithms. The distribution of errors is evaluated both at the stop level and the public transport zonal level, given the geographical attributes of each zone and the attributes of the smartcard transactions. While the results show significant associations between zone attributes as well as transaction attributes and the alighting stop inference errors, they undermine the existing algorithm's assumption that 'travellers alight a public transport service at a stop which is the closest to their next boarding stop'. Accordingly, this study proposes and evaluates the application of a probabilistic approach using neural networks to infer alighting stops based on a combination of transactional and public transit network attributes. The proposed method is validated using 138,122 smartcard transactions obtained during a normal day in Southeast Queensland, Australia. The results show that our method can improve the accuracy of the existing algorithm by inferring the exact location of 79.5% of the alighting stops and reducing the mean alighting estimation error from 1689 to 503 m for incorrectly estimated alighting stops. At the zonal level, the proposed method also improves the accuracy of the existing algorithm by more than 5%. Finally, the study provides both researchers and practitioners with a method to improve the accuracy of the trip-chaining algorithm and OD estimation, and presents a list of practical guidelines for more effective planning and operation of public transit services. [ABSTRACT FROM AUTHOR]

We study an airport cost function with a four-random components stochastic frontier model that split the inefficiency in two parts: (1) persistent (long-run) and (2) temporary (short-run). We analyze as determinant of both inefficiency types several exogenous factors such as the airport ownership and LCCs share. We apply the model to the Italian airport system during the period 2010–15. We find that (1) average total cost inefficiency is 14%, and that a it is mainly due to temporary inefficiency, (2) that work load units have the largest cost–output elasticity (+0.31%), (3) that price of airport services has the largest cost-input elasticity (+0.50%) while labor has a +0.41% cost elasticity and capital only a +0.09% cost elasticity. There is also evidence of economies of scale. Moreover we find that LCCs reduce both types of inefficiency and that private airports are more cost efficient than public ones. These findings have interesting managerial (e.g., strictly monitoring service costs, expand LCCs flights) and policy (e.g., provide incentive to reduce temporary inefficiency, push airport privatization) implications. [ABSTRACT FROM AUTHOR]

Globalization and production concentration have led to more efficient supply chain networks, which has led to the emergence of different types of risks. Although most companies have implemented special risk management programs, there may be events that can not be controlled by businesses, and unwanted consequences are not delayed.

Objective: A referendum took place in Greece on the 5 th of July 2015 to decide whether the suggested bailout would be accepted. Since this was the first one since 1974, the period between the referendum and the subsequent national elections was characterized by increased uncertainty and had spillover effects in many aspects of everyday life. We take advantage of this quasi-experiment to investigate the short-term impact of the referendum on vehicle collisions casualties., Methods: We use data from the daily number of injuries and fatalities caused by vehicle collisions in 2015 and employ a difference-in-differences approach, comparing trends before and after the referendum., Results: We reveal that the referendum had a short-term impact on road traffic casualties (4.14 more casualties per day), compared to what would have been expected in the absence of the referendum., Conclusions: The study provides evidence that negative emotions and anxiety, due to uncertainty, could promote dangerous driving behavior. Preventive and traffic control measures may need to be considered by policy makers during periods of uncertainty.