Factors influencing demand for public transport in Colombia

The article studies the demand for public transport in Colombian cities, identifying the main determinants explaining market shares for transit services. We used aggregated choice models to estimate overall price, income, speed and frequency elasticities for urban public transport demand in the country. The model successfully accounts for unobservable information about attributes of alternative public transport modes. The results suggest high demand elasticities to price and frequency, while demand responds moderately to speed. We also find a negative income elasticity, which classifies public transport as an inferior good. Results provide relevant information for the current discussion about new transport systems in cities of developing countries, with a deeper understanding of the elements to consider in the design of public transport policies. © 2020 Elsevier Lt

Reemplazo económico de los equipos

La decisión de reemplazar un equipo implica un análisis económico que incluya los costos fijos y variables, así como aquellos en los que se incurre cuando la maquinaria está parada por causa de las reparaciones, que son cada vez más frecuentes a la medida que ésta envejece. En este artículo se presenta un método sencillo, que requiere información muy fácil de obtener, y que a través de la evaluación de los costos anuales promedios acumulados permite al administrador del equipo tomar las decisiones pertinentes al reemplazo maximizando la utilidad proveniente de su explotación

Factors Influencing Crash Frequency on Colombian Rural Roads

Traffic crashes in Colombia have become a public health problem causing about 7,000 deaths and 45,000 severe injuries per year. Around 40% of these events occur on rural roads, taking note that the vulnerable users (pedestrians, motorcyclists, cyclists) account for the largest percentage of the victims. The objective of this research is to identify the factors that influence the frequency of crashes, including the singular orography of the country. For this purpose, we estimated Negative Binomial (Poisson-gamma) regression, Zero-inflated model, and generalized the linear mixed model, thus developing a comparative analysis of results in the Colombian context. The data used in the study came from the official sources regarding records about crashes with consequences; that is, with the occurrence of fatalities or injuries on the Colombian roads. For collecting the highway characteristics, an in-field inventory was conducted, gathering information about both infrastructure and operational parameters in more than three thousand kilometres of the national network. The events were geo-referenced, with registries of vehicles, involved victims, and their condition. The results suggest that highways in flat terrain have higher crash frequency than highways in rolling or mountainous terrain. Besides, the presence of pedestrians, the existence of a median and the density of intersections per kilometre also increase the probability of crashes. Meanwhile, roads with shoulders and wide lanes have lower crash frequency. Specific interventions in the infrastructure and control for reducing crashes risk attending the modelling results have been suggested.</p

The positive impacts of designing transition between traffic signal plans considering social cost

ABSTRACT: Traffic congestion generates social costs associated with additional travel time, fuel consumption and gas emissions, among others externalities. The design and implementation of policies and strategies for improving the efficiency of transport systems and mobility in cities may lead to a potential reduction of such externalities. Traffic signals plans are defined as the process of switching from one timing plan to another. The optimal implementation of the transition between signal plans is a strategy to improve the performance of signal systems. However, despite their importance, few studies have addressed it from a social approach using mathematical modelling and optimisation techniques. The purpose of this article is to evaluate the impacts of implementing the transition between signal timing plans designed from a mathematical model that minimises social costs (delays, air pollution emissions and fuel consumption). Impacts are evaluated for an arterial corridor traffic lights intersections in the city of Santander (Spain). The performance for reducing social costs of the proposed model was compared with other traditional methods. Results show that the proposed model overperforms the traditional approaches, reducing the level of externalities and social costs. Consideration of social costs when designing a transition between signal plans is a good tool to be considered by traffic planners

Evaluación de los parámetros de las funciones de costo en la red estratégica de transporte de carga para Colombia

Strategic freight transportation modeling has been a topic of growing interest because of its use for evaluating projects. One of the most important topics is to appraisal the parameters that define the level of service in links. This article presents the evaluation of the cost functions parameter, involving internal and external costs, which were applied to the intermodal network in Colombia, using a methodology that could be easily transferred to other transportation contexts. Considering different link typologies, we study the internal cost of time and operation, in addition to the five components of external costs: congestion, accidents, pollution, climate change, and damage on infrastructure. It was possible to estimate cost function parameters for different modes: road, rail and inland waterways, and to analyze the marginal costs on the Colombian freight transportation strategic network.La modelación estratégica del transporte de carga ha sido un tema de creciente interés por su utilidad para la evaluación de proyectos. Uno de los tópicos relevantes es la valoración de los parámetros que definen los niveles de servicio de los arcos; tema que es tratado en este artículo, en el que se valoran los parámetros de las funciones de costos, involucrando costos internos y externos, para la red intermodal colombiana, empleando una metodología que se podría aplicar fácilmente en otros sistemas de transporte. Estableciendo tipologías de arcos, se estudian los costos internos referidos al valor del tiempo y los costos de operación; adicionalmente, se estudian cinco componentes de costos externos: congestión, accidentes, polución, efectos sobre cambio climático y daños a infraestructura. Se logró valorar los parámetros de las funciones de costos en arcos de los modos transporte carretero, ferroviario y fluvial y, con ellos, estudiar los costos marginales sobre la red estratégica de transporte de carga de Colombia

Real-world Implementation of a Smartphone-Based Psychoeducation Program for Bipolar Disorder: Observational Ecological Study

Background: SIMPLe is an internet-delivered self-management mobile app for bipolar disorder (BD) designed to combine technology with evidence-based interventions and facilitate access to psychoeducational content. The SIMPLe app was launched to the real world to make it available worldwide within the context of BD treatment. Objective: The main aims of this study are as follows: to describe app use, engagement, and retention rates based on server data; to identify patterns of user retention over the first 6-month follow-up of use; and to explore potential factors contributing to discontinuation of app use. Methods: This was an observational ecological study in which we pooled available data from a real-world implementation of the SIMPLe app. Participation was open on the project website, and the data-collection sources were a web-based questionnaire on clinical data and treatment history administered at inclusion and at 6 months, subjective data gathered through continuous app use, and the use patterns captured by the app server. Characteristics and engagement of regular users, occasional users, and no users were compared using 2-tailed t tests or analysis of variance or their nonparametric equivalent. Survival analysis and risk functions were applied to regular users' data to examine and compare use and user retention. In addition, a user evaluation analysis was performed based on satisfaction, perceived usefulness, and reasons to discontinue app use. Results: We included 503 participants with data collected between 2016 and 2018, of whom 77.5% (n=390) used the app. Among the app users, 44.4% (173/390) completed the follow-up assessment, and data from these participants were used in our analyses. Engagement declined gradually over the first 6 months of use. The probability of retention of the regular users after 1 month of app use was 67.4% (263/390; 95% CI 62.7%-72.4%). Age (P=.002), time passed since illness onset (P<.001), and years since diagnosis of BD (P=.048) correlate with retention duration. In addition, participants who had been diagnosed with BD for longer used the app on more days (mean 97.73, SD 69.15 days; P=.002) than those who had had a more recent onset (mean 66.49, SD 66.18 days; P=.002) or those who had been diagnosed more recently (mean 73.45, SD 66 days; P=.01). Conclusions: The user retention rate of the app decreased rapidly after each month until reaching only one-third of the users at 6 months. There exists a strong association between age and app engagement of individuals with BD. Other variables such as years lived with BD, diagnosis of an anxiety disorder, and taking antipsychotics seem relevant as well. Understanding these associations can help in the definition of the most suitable user profiles for predicting trends of engagement, optimization of app prescription, and management

Gestión del conocimiento. Perspectiva multidisciplinaria. Volumen 17

El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, Volumen 17 de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro es una publicación internacional, seriada, continua, arbitrada, de acceso abierto a todas las áreas del conocimiento, orientada a contribuir con procesos de gestión del conocimiento científico, tecnológico y humanístico. Con esta colección, se aspira contribuir con el cultivo, la comprensión, la recopilación y la apropiación social del conocimiento en cuanto a patrimonio intangible de la humanidad, con el propósito de hacer aportes con la transformación de las relaciones socioculturales que sustentan la construcción social de los saberes y su reconocimiento como bien público

Factors influencing demand for public transport in Colombia

The article studies the demand for public transport in Colombian cities, identifying the main determinants explaining market shares for transit services. We used aggregated choice models to estimate overall price, income, speed and frequency elasticities for urban public transport demand in the country. The model successfully accounts for unobservable information about attributes of alternative public transport modes. The results suggest high demand elasticities to price and frequency, while demand responds moderately to speed. We also find a negative income elasticity, which classifies public transport as an inferior good. Results provide relevant information for the current discussion about new transport systems in cities of developing countries, with a deeper understanding of the elements to consider in the design of public transport policies

Reemplazo económico de los equipos

La decisión de reemplazar un equipo implica un análisis económico que incluya los costos fijos y variables, así como aquellos en los que se incurre cuando la maquinaria está parada por causa de las reparaciones, que son cada vez más frecuentes a la medida que ésta envejece. En este artículo se presenta un método sencillo, que requiere información muy fácil de obtener, y que a través de la evaluación de los costos anuales promedios acumulados permite al administrador del equipo tomar las decisiones pertinentes al reemplazo maximizando la utilidad proveniente de su explotación

Generación de viajes en el distrito de Barranquilla

En los procesos de planificación del transporte urbano es necesario cuantificar la demanda de viajes y contrastarla con la oferta, lo cual exige el desarrollo de modelos. El grupo de Investigación en Geotecnia, Vías y Transporte de la Universidad del Norte ha trabajado durante los dos últimos años en el desarrollo de modelos de transporte urbano, que han permitido estimar uno de los componentes más importantes de la demanda de transporte urbano en la ciudad de Barranquilla como es la generación de viajes. Este artículo presenta los resultados más relevantes de la generación de viajes en los diferentes estratos socioeconómicos de la ciudad