Simulating train movement in an urban railway based on an improved car-following model

Based on the optimal velocity car-following model, in this paper, we propose an improved model for simulating train movement in an urban railway in which the regenerative energy of a train is considered. Here a new additional term is introduced into a traditional car-following model. Our aim is to analyze and discuss the dynamic characteristics of the train movement when the regenerative energy is utilized by the electric locomotive. The simulation results indicate that the improved car-following model is suitable for simulating the train movement. Further, some qualitative relationships between regenerative energy and dynamic characteristics of a train are investigated, such as the measurement data of regenerative energy presents a power-law distribution. Our results are useful for optimizing the design and plan of urban railway systems.

A methodology for assessing the urban supply of on-street delivery bays

The loading and unloading operations carried out by transport and logistics operators have a strong impact on city mobility if they are not performed correctly.If loading/unloading bays,i.e.,delivery bays(DB),are not available for freight vehicle operations,operators may opt to double park or park on the sidewalk where there is no strong enforcement of these laws,with significant impact on congestion.This paper proposes a methodology for verifying and designing the number of delivery bays needed for freight vehicles for not interfere with cars or pedestrians.The methodology consists of two stages:in the first stage,an initial estimation is made using queueing theory.Subsequently,in the second stage,using such tentative scenario,in order to take into account the system stochasticity involving different entities,a discrete event simulation is performed to more realistically verify and upgrade(if necessary)the number of delivery bays to obtain the expected outcomes.The methodology was applied in the inner area of Santander(Spain).The study area was subdivided into 29 zones where the methodology was applied individually.The results indicated that none of these zones currently have an optimal number of delivery bays to satisfy demand.In some zones,there is an excess of delivery bays,although in most of them,there is a deficit which can cause significant impacts on traffic.The method proposed can be an effective tool to be used by city planners for improving freight operations in urban areas limiting the negative impacts produced in terms of internal and external costs.