Search results for " transportation"
showing 10 items of 511 documents
The combined distribution/assignment problem in transportation network planning: a parallel approach on hypercube architecture
1995
The joint distribution/assignment problem plays a central role in urban transport network planning. In this problem, according to the mathematical model proposed by S. P. Evans, the trips are iteratively calculated and assigned to the network in such a way that the resulting traffic flows pattern satisfies the selfish equilibrium condition. Unfortunately the number of variables and constraints increase hardly with the greatness of the networks causing long computational time for the equilibrium solution. In this paper an nCUBE 2 parallel computing architecture is employed to solve the combined problem and to asses the potential of MIMD machines to handle large scale transportation network p…
Cumbersome but desirable—Breaking the code of everyday cycling
2020
IntroductionCycling for transport could integrate physical activity (PA) into daily routines and potentially increase total PA levels. However, for parents with young children, most factors affecting transport mode choice tend to facilitate car use. Greater insight is necessary into reasons for (not) using sustainable transport modes in parents with young children. Therefore, the objective of this study was to explore the experiences, including motives, perceptions, attitudes, and norms, of parents of young children by using an e-bike, a longtail bike, and a traditional bike for everyday travel to the workplace, kindergarten, and the grocery store during the autumn, winter, and spring, in n…
Finite speed of propagation in porous media by mass transportation methods
2004
Abstract In this Note we make use of mass transportation techniques to give a simple proof of the finite speed of propagation of the solution to the one-dimensional porous medium equation. The result follows by showing that the difference of support of any two solutions corresponding to different compactly supported initial data is a bounded in time function of a suitable Monge–Kantorovich related metric. To cite this article: J.A. Carrillo et al., C. R. Acad. Sci. Paris, Ser. I 338 (2004).
Estimation of Passenger Car Equivalents for single-lane roundabouts using a microsimulation-based procedure
2017
Calibration of microscopic traffic simulation models for single-lane roundabouts.Use of a meta-analytical estimation of critical and follow up headways.Use of a genetic algorithm-based procedure.Calculation of passenger car equivalents for single-lane roundabouts. Passenger car equivalents for heavy vehicles are required to carry out capacity calculations and perform operational analysis of any road entity (roadway segments or intersections). At single-lane roundabouts, the constraints to the vehicular trajectories imposed by the curvilinear geometric design and the driver's gap acceptance behaviour are expected to produce an impact of the heavy vehicles on the quality of traffic flow diffe…
A GIS-Based Method to Assess the Pedestrian Accessibility to the Railway Stations
2018
Modern cities, affected by congestion, atmospheric and acoustic pollution, land consumption, should change and return to being on a human scale, rather than designed for cars. Proper land-use planning, infrastructure improvement and implementation of targeted interventions have to ensure that there is a rapprochement of citizens about the public transport, in order to reduce these problems. An important aspect of modal choice by users of the public transport system is, however, linked to the quality of the pedestrian routes. In fact, every journey made by public transport begins and finishes on foot. Therefore, studying pedestrian accessibility to transit stations and the walkability of the…
The Challenges of Urban Mobility Regulation and the New Urban Agenda
2019
The objectives set by the United Nations New Urban Agenda pose important challenges to the traditional regulation of urban mobility in our cities. Regardless of the region of the world in question and its level of development, the goals established by the Agenda expose the importance of improving urban mobility regulation. Therefore, some traditional regulatory approaches need to be modified or intensified, which is potentially difficult in certain cases. In addition, and complicating the matter further – as well as being more interesting from an academic perspective – the disruptive emergence of new agents and market niches related to urban transportation (such as digital sharing platforms…
An empirically grounded agent based simulator for the air traffic management in the SESAR scenario
2017
In this paper we present a simulator allowing to perform policy experiments relative to the air traffic management. Different SESAR solutions can be implemented in the model to see the reaction of the different stakeholders as well as other relevant metrics (delay, safety, etc). The model describes both the strategic phase associated to the planning of the flight trajectories and the tactical modifications occurring in the en-route phase. An implementation of the model is available as an open-source software and is freely accessible by any user. More specifically, different procedures related to business trajectories and free-routing are tested and we illustrate the capabilities of the mode…
Estimating pollutant emissions based on speed profiles at urban roundabouts: A pilot study
2019
The paper describes the pilot study conducted to assess the feasibility of the empirical approach utilizing vehicle trajectory data from a smartphone app and the Vehicle-Specific Power methodology to estimate pollutant emissions at urban roundabouts. The goal of this research phase is to acquire instantaneous speed data from a sample of six roundabouts located in the road network of the City of Palermo, Italy, and quantify emissions generated by the test vehicle through the examined roundabouts. For the case studies of roundabouts acceleration events in the circulating and exiting areas contributed to about 25% of the emissions for a given speed profile. More in general, the results from th…
Knowledge, perceived effectiveness and qualification of traffic rules, police supervision, sanctions and justice
2017
Road safety is a complex process that not only depends on technical and environmental improvements, but in a major part from human factors. In this sense, recent empirical studies have remarked the need to study the interaction between subject and laws, at the glance of several elements preceding road behavior. This is the case of attitudes, opinions and perceptions in the field of road safety, factors that influence the interaction with issues such as traffic rules, police supervision, penalties and justice in traffic. The objective of this study was to describe the self-rated knowledge and perceptions regarding traffic norms and its interaction with road safety among drivers. For this stu…
Working conditions, job strain, and traffic safety among three groups of public transport drivers
2018
Background: Working conditions and psychosocial work factors have acquired an important role explaining the well-being and performance of professional drivers, including those working in the field of public transport. This study aimed to examine the association between job strain and the operational performance of public transport drivers and to compare the expositions with psychosocial risk at work of three different types of transport workers: taxi drivers, city bus drivers, and interurban bus drivers. Method: A sample of 780 professional drivers was drawn from three transport companies in Bogota (Colombia). The participants answered the Job Content Questionnaire and a set of sociodemogra…