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This paper presents the optimization problem of three different on-demand transit systems operated by vehicles of different sizes. This problem is aimed at minimizing the total cost of the system, which consists of the temporal cost experienced by users and the operating cost incurred by transit agencies. A compact set of estimations of the user performance and operating cost is provided, based on geometric probability. The optimization procedure allows the cost comparison of different semi-flexible services. Transit systems operated by cars (shared taxicabs) with flexible layouts are preferable for low demand densities (less than 92 pax/km2-h). For very high demand (higher than 200 pax/km2-h), bus systems with fixed layout and variable stop locations present the lowest total cost per passenger. In an intermediate domain, taxi and semi-flexible services compete among each other. The estimation of unit operating costs allows decision-makers to calculate the subsidies needed to make the system profitable.
Miquel Estrada; Josep Maria Salanova; Marcos Medina-Tapia; Francesc Robusté. Operational cost and user performance analysis of on-demand bus and taxi systems. Transportation Letters 2020, 13, 229 -242.
AMA StyleMiquel Estrada, Josep Maria Salanova, Marcos Medina-Tapia, Francesc Robusté. Operational cost and user performance analysis of on-demand bus and taxi systems. Transportation Letters. 2020; 13 (3):229-242.
Chicago/Turabian StyleMiquel Estrada; Josep Maria Salanova; Marcos Medina-Tapia; Francesc Robusté. 2020. "Operational cost and user performance analysis of on-demand bus and taxi systems." Transportation Letters 13, no. 3: 229-242.
The concentration of both employment and services in a specific area of a town generates positive effects, but also impacts (congestion, transit issues, and others). Urban subcenters seek to approach economic activities to residents in peripheral urban spaces. The objective of this research is to evaluate the contribution to the mobility of implementing urban subcenters in a city. The model has a total cost function (users and agency costs) on a circular city (ring and radial routes) formulated using the continuous approximation method. The model solution addresses with mathematical optimization. The model evaluates a BRT network applied to scenarios of urban subcenters. The results of the modeling show that the implementation of subcenters obtains savings of 3.5% in rush hour. Thus, this strategy of urban planning generates improvements in the functioning of a public transportation system. Moreover, the maximum benefits are obtained in medium-sized subcenters in comparison to the CBD, which allows balancing user and agency costs. Therefore, the outcomes may be better with an urban pattern with subcenters, and a transit scheme adapted to the demand needs.
Marcos Medina-Tapia; Francesc Robusté; Miquel Estrada. Modeling public transportation networks for a circular city: the role of urban subcenters and mobility density. Transportation Research Procedia 2020, 47, 353 -360.
AMA StyleMarcos Medina-Tapia, Francesc Robusté, Miquel Estrada. Modeling public transportation networks for a circular city: the role of urban subcenters and mobility density. Transportation Research Procedia. 2020; 47 ():353-360.
Chicago/Turabian StyleMarcos Medina-Tapia; Francesc Robusté; Miquel Estrada. 2020. "Modeling public transportation networks for a circular city: the role of urban subcenters and mobility density." Transportation Research Procedia 47, no. : 353-360.
Autonomous vehicles promise to revolutionize the automobile market, although their implementation could take several decades in which both types of cars will coexist on the streets. We formulate a model for a circular city based on continuous approximations, considering demand surfaces over the city. Numerical results from our model predict direct and indirect effects of connected and autonomous vehicles. Direct effects will be positive for our cities: (a) less street supply is needed to accommodate the traffic; (b) congestion levels decrease: travel costs may decrease by 30%. Some indirect effects will counterbalance these positive effects: (c) a decrease of 20% in the value of travel time can reduce the total cost by a third; (d) induced demand could be as high as 50%, bringing equivalent total costs in the future scenario; (e) the vehicle-kilometers traveled could also affect the future scenario; and (f) increases in city size and urban sprawl. As a conclusion, the implementation of autonomous vehicles could be neutral for the cities regarding travel time costs. City planning agencies still have to promote complementary modes such as active mobility (walking and bicycle), transit (public transportation), and shared mobility (shared autonomous vehicles and mobility as a service).
Marcos Medina-Tapia; Francesc Robusté. Implementation of Connected and Autonomous Vehicles in Cities Could Have Neutral Effects on the Total Travel Time Costs: Modeling and Analysis for a Circular City. Sustainability 2019, 11, 482 .
AMA StyleMarcos Medina-Tapia, Francesc Robusté. Implementation of Connected and Autonomous Vehicles in Cities Could Have Neutral Effects on the Total Travel Time Costs: Modeling and Analysis for a Circular City. Sustainability. 2019; 11 (2):482.
Chicago/Turabian StyleMarcos Medina-Tapia; Francesc Robusté. 2019. "Implementation of Connected and Autonomous Vehicles in Cities Could Have Neutral Effects on the Total Travel Time Costs: Modeling and Analysis for a Circular City." Sustainability 11, no. 2: 482.
Urban mobility is a dynamic system that has had a (slow) natural evolution. Scientists and engineers are currently developing new mobility technologies. A progressive paradigm shift will change everything from the fuel type to the way of driving vehicles. Vehicles will progressively become autonomous and will communicate and cooperate with each other. In the long run, profound changes are expected in mobility as a service. Furthermore, urban areas will have a higher level of development, and cities will likely turn into Smart Cities in which the vehicles will interact with the urban infrastructure. The main objective of this paper is to explore the macroscopic effects of mobility interaction in a radial-circular urban road system for current and future cities (Smart Cities). In the literature, there is documentation of the direct effects of autonomous vehicles, but some indirect effects will cause undesirable impacts such as an increase in demand and more congestion, which change the demand behavior and the urban structure. Finally, this paper exhibits the results of direct and indirect effects calculated through analytical tools (Continuous Approximation Method). In fact, our research shows that if demand increases by about 50%, the current scenario could have the same total cost as the future scenario with autonomous vehicles. Moreover, if the city radius increases by about 33% and the subjective value of time decreases about 20%, the benefits of the autonomous cars will be compensated. Therefore, the paper proves that autonomous vehicles could encourage the urban sprawl in the long run. Finally, Administrations should define transport strategies and policies to control these externalities, because autonomous driving could deteriorate mobility even worse than it is now.
Marcos Medina-Tapia; Francesc Robusté. Exploring paradigm shift impacts in urban mobility: Autonomous Vehicles and Smart Cities. Transportation Research Procedia 2018, 33, 203 -210.
AMA StyleMarcos Medina-Tapia, Francesc Robusté. Exploring paradigm shift impacts in urban mobility: Autonomous Vehicles and Smart Cities. Transportation Research Procedia. 2018; 33 ():203-210.
Chicago/Turabian StyleMarcos Medina-Tapia; Francesc Robusté. 2018. "Exploring paradigm shift impacts in urban mobility: Autonomous Vehicles and Smart Cities." Transportation Research Procedia 33, no. : 203-210.
Las paradas de transporte público (TP), tanto en su distribución como en su localización, son generalmente analizadas desde un punto de vista macroscópico, utilizando modelos analíticos para observar tanto una línea de buses, en particular, o la red de transporte público, en general. Sin embargo, la importancia y complejidad de lograr una buena operación de las paradas de transporte público y en particular lograr que éstas tengan una buena accesibilidad, requiere de un análisis más detallado. Actualmente no existen desarrollos metodológicos que solucionen este problema, menos aún en el caso de proyectos viales de mejora de la infraestructura urbana que implican una intervención importante de un sector de la ciudad, por lo que en este trabajo se propone una metodología de localización de paradas de transporte público que a través de un modelo matemático de optimización permita ubicar dichos paraderos provisorios a lo largo de las calles propuestas en un Plan de Desvíos de manera tal de optimizar la accesibilidad de los usuarios al transporte público. Esta metodología fue aplicada a un caso real de estudio en la intersección de las avenidas 5 de Abril – Esquina Blanca con Avenida Del Ferrocarril de Santiago, Chile, y los resultados muestran que se puede mantener y, en algunos casos, mejorar el nivel de servicio del transporte público desde el punto de vista de la accesibilidad al mismo. Por lo tanto, se demuestra la importancia y el aporte que esta metodología puede tener para mejorar la planificación de los Planes de Desvío por obras de mejoramiento vial al incorporar la variable accesibilidad al transporte público.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4253
Marcos Medina-Tapia; Cristian Baeza; Daniel Arancibia; Francesc Robusté. Relocalización de paradas de transporte público para ser incorporado dentro planes de contingencia como resultado de la construcción de obras de mejora vial. Libro de Actas CIT2016. XII Congreso de Ingeniería del Transporte 2016, 1 .
AMA StyleMarcos Medina-Tapia, Cristian Baeza, Daniel Arancibia, Francesc Robusté. Relocalización de paradas de transporte público para ser incorporado dentro planes de contingencia como resultado de la construcción de obras de mejora vial. Libro de Actas CIT2016. XII Congreso de Ingeniería del Transporte. 2016; ():1.
Chicago/Turabian StyleMarcos Medina-Tapia; Cristian Baeza; Daniel Arancibia; Francesc Robusté. 2016. "Relocalización de paradas de transporte público para ser incorporado dentro planes de contingencia como resultado de la construcción de obras de mejora vial." Libro de Actas CIT2016. XII Congreso de Ingeniería del Transporte , no. : 1.
The location and number of bus stops are key to the operational efficiency of the services that use them; these criteria affect commercial speed, reliability, and passenger access times. In the defining of the number of stops, a trade-off arises between reduced access time, which widens a route's coverage area, and both the operational speed of the route and the users’ in-vehicle travel time. In this study, a model for optimally locating stops was developed, and the model was applied to the Grecia Avenue public transport corridor in the city of Santiago, Chile. The proposed model uses a continuous and multiperiod approximation of corridor demand; this approximation allows for the determination of the density of stops, which minimizes the sum of operator costs and total costs to passengers. The model simultaneously solves for the optimal stop density and the headway between successive buses. The actual stop locations of the Grecia Avenue corridor were compared with the optimal locations suggested by the model, and many similarities were found.
Marcos Medina; Ricardo Giesen; Juan Carlos Muñoz. Model for the Optimal Location of Bus Stops and Its Application to a Public Transport Corridor in Santiago, Chile. Transportation Research Record: Journal of the Transportation Research Board 2013, 2352, 84 -93.
AMA StyleMarcos Medina, Ricardo Giesen, Juan Carlos Muñoz. Model for the Optimal Location of Bus Stops and Its Application to a Public Transport Corridor in Santiago, Chile. Transportation Research Record: Journal of the Transportation Research Board. 2013; 2352 (1):84-93.
Chicago/Turabian StyleMarcos Medina; Ricardo Giesen; Juan Carlos Muñoz. 2013. "Model for the Optimal Location of Bus Stops and Its Application to a Public Transport Corridor in Santiago, Chile." Transportation Research Record: Journal of the Transportation Research Board 2352, no. 1: 84-93.
Marcos Medina-Tapia; Jorge Cerda Troncoso. MODELO DE LOCALIZACIÓN ÓPTIMA DE ACTIVIDADES NO DESEADAS APLICADO A LOS RESIDUOS SÓLIDOS EN LA REGIÓN METROPOLITANA. Ingeniare. Revista chilena de ingeniería 2008, 16, 211 -219.
AMA StyleMarcos Medina-Tapia, Jorge Cerda Troncoso. MODELO DE LOCALIZACIÓN ÓPTIMA DE ACTIVIDADES NO DESEADAS APLICADO A LOS RESIDUOS SÓLIDOS EN LA REGIÓN METROPOLITANA. Ingeniare. Revista chilena de ingeniería. 2008; 16 (1):211-219.
Chicago/Turabian StyleMarcos Medina-Tapia; Jorge Cerda Troncoso. 2008. "MODELO DE LOCALIZACIÓN ÓPTIMA DE ACTIVIDADES NO DESEADAS APLICADO A LOS RESIDUOS SÓLIDOS EN LA REGIÓN METROPOLITANA." Ingeniare. Revista chilena de ingeniería 16, no. 1: 211-219.