Sensitivity of the subjective value of travel time for different microeconomic models: empirical evidence for university students

ABSTRACT: This paper analyses the sensitivity of the subjective value of travel time (SVT) by considering different models based on the microeconomic theory of time allocation, as well as different econometric specifications of discrete choice models, and provides empirical evidence of this. Thus, the objective is to estimate wage rate and expenditure rate models together with a model that includes cost-weighted income. For this purpose we use discrete choice econometric models in which heterogeneity among individuals is introduced. Taking into account that the most important benefit of a transport infrastructure project is the value of the travel time saved, the subjective value of time (SVT), the results allow us to determine which microeconomic model and empirical specification are the most robusto In addition, we can obtain comparisons of the values obtained for different countries and areas of study. For estimates, data from an origin-destination survey conducted among students at the University of Cantabria in the city of Santander (Spain) have been used

The Spanish airport system. An analysis of concentration and volatility

RESUMEN. En este trabajo se analiza la estructura del sistema aeroportuario español, en particular se realiza un estudio sobre la concentración y volatilidad en la distribución de pasajeros, tanto desde el punto de vista de los aeropuertos existentes como de las compañías aéreas que los utilizan. Asimismo, el estudio de la distribución de pasajeros dentro de cada aeropuerto permitirá observar el efecto que la inclusión de compañías de bajo coste ha tenido, permite determinar los efectos relativos a la crisis internacional, así como los cambios legislativos que han afectado a AENA (Aeropuertos Españoles y Navegación Aérea). Se han calculado una serie de índices de concentración y volatilidad a partir de datos de pasajeros de 46 aeropuertos españoles, desde 2004 hasta 2015. Los resultados apuntan hacia una estructura del sistema aeroportuario caracterizada por una concentración limitada y una volatilidad muy baja.ABSTRACT. This paper analyzes the structure of the Spanish airport system. In particular, it studies the concentration and volatility of passenger distribution, both from the point of view of the airport and the airline. Likewise, the study of passenger distribution within each airport allows observing the effect of the inclusion of low cost airlines; it allows determining the effects related to the international crisis, and the effects of the legislative changes that have affected AENA. A series of concentration and volatility indices are calculated using data on passengers for 46 Spanish airports from 2004 to 2015. The results point to an airport system structure characterized by limited concentration and very low volatility

Introduction to the special issue on structure and public policies in the air transport market

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The Influence of organizational factors on road transport safety

Road transport safety is a major concern across Europe due to the human and socio-economic costs associated with work-related traffic accidents. Traditional approaches have adopted regulatory and technical measures to prevent road accidents leaving aside the organizational factors that might contribute to road transport safety. However, contemporary sociotechnical systems theory acknowledges the need to take into account organizational factors. This study adopts a sociotechnical approach and it examines the relationship between a number of organizational factors (organizational learning and training) and road traffic accidents in the organizations under study. Our sample was composed of 107 road transportation organizations from Spain. Binary logistic regression analyses were carried out to test our hypotheses. Organizational size and type of transport (goods or passengers) were included in the model as control variables. Results showed that in those organizations where organizational learning was supported, the occurrence of traffic accidents was less likely. Unexpectedly, the relationship between training and the occurrence of traffic accidents was not significant. Thus, findings partially supported the formulated hypothesis. Future research should shed light on the relationship between training and traffic accidents taking into account potential intervening variables

Ridesourcing mode choice: a latent class choice model for UberX in Chile

As shared mobility expands, ridesourcing has become its most popular manifestation. However, users' mode choice has not yet been sufficiently explored. Thus, this study aims to model ridesourcing mode choice across different latent classes to ascertain who chose ridesourcing and why. We conducted a mode choice study by collecting revealed preference surveys from UberX users in Viña del Mar, Chile, in 2017. We then determined the existence of two latent classes and modeled the mode choice using a latent class choice model. Ultimately, we characterized individuals belonging to each latent class and calculated the subjective value of time (SVT). Most UberX users were highly educated and aged 20?35 years. Further, UberX gained users principally from public transport (80%). Likewise, the two latent classes differed by socioeconomic characteristics and SVTs. A latent class grouped the highest-educated and highest-earning users, who also offered the highest SVT. In summary, two latent classes, differentiated by educational level and income, formed the ridesourcing market. Besides, they offered distinct ridesourcing choice behavior based on the widely dissimilar SVTs. There was also a strong substitution effect between ridesourcing and transit use. The results imply that policymakers and transportation planners could have increased the competitiveness of the public transit system by improving rapidity and safety, having room to increase the fares to defray the improvements. Further, they could have used information related to the latent classes to customize relevant policies and marketing strategies (routes, frequency, fares, etc.) for every latent class

Modelling seed germination in forest tree species through survival analysis. The Pinus pinea L. case study

The direct application of existing models for seed germination may often be inadequate in the context of ecology and forestry germination experiments. This is because basic model assumptions are violated and variables available to forest managers are rarely used. In this paper, we present a method which addresses the aforementioned shortcomings. The approach is illustrated through a case study of Pinus pinea L. Our findings will also shed light on the role of germination in the general failure of natural regeneration in managed forests of this species. The presented technique consists of a mixed regression model based on survival analysis. Climate and stand covariates were tested. Data for fitting the model were gathered from a 5-year germination experiment in a mature, managed P. pinea stand in the Northern Plateau of Spain in which two different stand densities can be found. The model predictions proved to be unbiased and highly accurate when compared with the training data. Germination in P. pinea was controlled through thermal variables at stand level. At microsite level, low densities negatively affected the probability of germination. A time-lag in the response was also detected. Overall, the proposed technique provides a reliable alternative to germination modelling in ecology/forestry studies by using accessible/ suitable variables. The P. pinea case study highlights the importance of producing unbiased predictions. In this species, the occurrence and timing of germination suggest a very different regeneration strategy from that understood by forest managers until now, which may explain the high failure rate of natural regeneration in managed stands. In addition, these findings provide valuable information for the management of P. pinea under climate-change conditions

Sustainable Mobility Policy Analysis Using Hybrid Choice Models: Is It the Right Choice?

In recent years, sustainable mobility policy analysis has used Hybrid Choice Models (HCM) by incorporating latent variables in the mode choice models. However, the impact on policy analysis outcomes has not yet been determined with certainty. This paper aims to measure the effect of HCM on sustainable mobility policy analysis compared to traditional models without latent variables. To this end, we performed mode choice research in the city of Santander, Spain. We identified two latent variables -Safety and Comfort- and incorporated them as explanatory variables in the HCM. Later, we conducted a sensitivity study for sustainable mobility policy analysis by simulating different policy scenarios. We found that the HCM amplified the impact of sustainable mobility policies on the modal shares, and provided an excessive reaction in the individuals' travel behavior. Thus, the HCM overrated the impact of sustainable mobility policies on the modal switch. Likewise, for all of the mode choice models, policies that promoted public transportation were more effective in increasing bus modal shares than those that penalized private vehicles. In short, we concluded that sustainable mobility policy analysis should use HCM prudently, and should not set them as the best models beforehand

Optimization of the air cargo supply chain.

Purpose: This paper aims to evaluate and optimize the various operations within the air cargo chain. It pursues to improve the efficiency of the air cargo supply chain and to provide more information to the decision-makers to optimize their fields. Design/methodology/approach: The method used is a process simulation modelling software, WITNESS, which provides information to the decision-makers about the most relevant parameters subject to optimization. The input for the simulation is obtained from a qualitative analysis of the air cargo supply chain with the involved agents and from a study of the external trade by air mode, given that their behaviour depend on the location. The case study is focused on a particular location, the Case of Zaragoza Airport (Spain). Findings: This paper demonstrates that efficiency of the air cargo supply chain can increase by leveraging several parameters such as bottlenecks, resources or warehouses. Originality/value: It explores the use of a simulation modeling software originally intended for manufacturing processes and extended to support decision making processes in the area of air cargo

Incorporación de atributos intangibles en modelos de elección discreta

[ES] La principal herramienta en la modelación de la demanda de transporte durante muchos años ha sido el Logit Multinomial (MNL), pero sus limitaciones, fundamentalmente el supuesto de independencia de alternativas irrelevantes, han motivado diferentes mejoras, destacando entre ellas el Logit Mixto (ML). El ML permite mayor flexibilidad en las preferencias individuales, aunque no por ello ha colmado las expectativas de los modeladores, ya que el objetivo es representar la realidad de la forma más veraz posible. De este modo, se ha planteado la inclusión de elementos subjetivos, a través de modelos de utilidad híbridos que consideran atributos tangibles, fácilmente identificables para cada alternativa, así como elementos intangibles asociados a las percepciones y actitudes de los individuos, expresados a través de variables latentes. El principal objetivo de este trabajo es identificar las variables latentes relevantes en la modelación de la elección modal en el ámbito urbano, así como la estimación de MNL y ML con y sin variables latentes, con el fin de determinar si la inclusión de variables latentes mejora los resultados en la estimación de los modelos. La aplicación empírica se efectúa con datos obtenidos a partir de una encuesta de Preferencias Reveladas realizada en Santander (España), a la que se incorporó un cuestionario con indicadores de percepción, que permiten captar las variables latentes. La principal conclusión es que los modelos ML se muestran superiores a los MNL y, en ambos casos, la incorporación de variables latentes permite obtener mejores resultados.Garcia Melero, G.; Coto Millan, P.; Sainz González, R. (2016). Incorporación de atributos intangibles en modelos de elección discreta. En XII Congreso de ingeniería del transporte. 7, 8 y 9 de Junio, Valencia (España). Editorial Universitat Politècnica de València. 1067-1083. https://doi.org/10.4995/CIT2016.2015.4142OCS1067108

Nuevas tecnologías y valor del tiempo en el transporte de viajeros

En esta investigación se elabora un modelo original que permite obtener diferentes valores del tiempo de viaje y analizar como influyen las nuevas tecnologías en tales valores. Se proporciona un modelo teórico más general que los tradicionales, cuyo principal resultado es que el valor del tiempo de viaje, en presencia de nuevas tecnologías, es en términos generales inferior al correspondiente valor sin la presencia de tales nuevas tecnologías