Road Network Simulation Using FLAME GPU

Demand for high performance road network simulation is increasing due to the need for improved traffic management to cope with the globally increasing number of road vehicles and the poor capacity utilisation of existing infrastructure. This paper demonstrates FLAME GPU as a suitable Agent Based Simulation environment for road network simulations, capable of coping with the increasing demands on road network simulation. Gipps’ car following model is implemented and used to demonstrate the performance of simulation as the problem size is scaled. The performance of message communication techniques has been evaluated to give insight into the impact of runtime generated data structures to improve agent communication performance. A custom visualisation is demonstrated for FLAME GPU simulations and the techniques used are described

ANALIZA UTJECAJA PARAMETARA KOLONE VOZILA NA MODELIRANO VRIJEME PUTOVANJA

The calibration process is a basic condition of traffic model application in local conditions. The choice of input parameters, which are used in calibration process, influences the success of the calibration process itself; therefore, the goal is to choose parameters with a larger influence on the modelling process. This paper offers a detailed analysis of car-following input parameters and their influence on the modelled travelling time. The experimental basis was a one-lane roundabout, and the tool used for traffic simulation was the VISSIM microsimulation traffic model. The results show that the car-following input parameters should be a part of the set of input parameters, which will enter the process of calibration. The examined car-following input parameters affect the capacity of intersections and results show that it is necessary to revise the range of input values of one of the observed car-following input parameters.Postupak kalibracije je uvjet primjenjivosti prometnih modela u lokalnim uvjetima. Izbor ulaznih parametara koji će ući u postupak kalibracije utječe na uspješnost postupka kalibracije, pa je cilj odabrati parametre koji imaju veći utjecaj na rezultate modeliranja. U ovom radu detaljnije su analizirani parametri kolone vozila i njihov utjecaj na modelirano vrijeme putovanja. Eksperimetalna baza bilo je jednotračno kružno raskrižje, a kao alat prometnih simulacija služio je VISSIM mikrosimulacijski model. Rezultati pokazuju da parametri kolone vozila trebaju biti u skupu ulaznih parametara koji će ući u postupak kalibracije. Promatrani parametri kolone utječu na propusnu moć raskrižja, a rezultati pokazuju da je potrebno revidirati raspon ulaznih vrijednosti jednog od analiziranih parametara

Modelling Acceleration Decisions in Traffic Streams with Weak Lane Discipline: A Latent Leader Approach

Acceleration is an important driving manoeuvre that has been modelled for decades as a critical element of the microscopic traffic simulation tools. The state-of-the art acceleration models have however primarily focused on lane based traffic. In lane based traffic, every driver has a single distinct lead vehicle in the front and the acceleration of the driver is typically modelled as a function of the relative speed, position and/or type of the corresponding leader. On the contrary, in a traffic stream with weak lane discipline, the subject driver may have multiple vehicles in the front. The subject driver is therefore subjected to multiple sources of stimulus for acceleration and reacts to the stimulus from the governing leader. However, only the applied accelerations are observed in the trajectory data, and the governing leader is unobserved or latent. The state-of-the-art models therefore cannot be directly applied to traffic streams with weak lane discipline. This prompts the current research where we present a latent leader acceleration model. The model has two components: a random utility based dynamic class membership model (latent leader component) and a class-specific acceleration model (acceleration component). The parameters of the model have been calibrated using detailed trajectory data collected from Dhaka, Bangladesh. Results indicate that the probability of a given front vehicle of being the governing leader can depend on the type of the lead vehicle and the extent of lateral overlap with the subject driver. The estimation results are compared against a simpler acceleration model (where the leader is determined deterministically) and a significant improvement in the goodness-of-fit is observed. The proposed models, when implemented in microscopic traffic simulation tools, are expected to result more realistic representation of traffic streams with weak lane discipline

Plataforma de simulación y visualización para el apoyo al análisis y toma de decisiones en proyectos de movilidad urbana

Este artículo presenta los resultados parciales de la implementación de una plataforma de simulación y visualización para apoyar procesos de análisis y toma de decisiones en proyectos de movilidad urbana. La posibilidad de representar anomalías en la infraestructura vial y en el comportamiento de los diferentes actores, permite su potencial aplicación en escenarios de las ciudades latinoamericanas. Los resultados se presentan en los siguientes temas: modelo de simulación y visualización, aplicaciones de simulación y visualización

AGENT-BASED MODELING FOR TRAFFIC SIMULATION

In  this  paper  we  develop  a  multi-agent  based  traffic  simulator  by  considering traffic  flows as emergent phenomena. The main  problem  of  agent-based  traffic  simulation  is how  to  reproduce  realistic  patterns  of  traffic  flow  at  both macroscopic and microscopic. The objective of simulation is a scenario of  traffic generated by the model  that should provide  the illusion of a real road scenario

Analysis of the influence of car-following input parameters on the modelled travelling time

Postupak kalibracije je uvjet primjenjivosti prometnih modela u lokalnim uvjetima. Izbor ulaznih parametara koji će ući u postupak kalibracije utječe na uspješnost postupka kalibracije, pa je cilj odabrati parametre koji imaju veći utjecaj na rezultate modeliranja. U ovom radu detaljnije su analizirani parametri kolone vozila i njihov utjecaj na modelirano vrijeme putovanja. Eksperimetalna baza bilo je jednotračno kružno raskrižje, a kao alat prometnih simulacija služio je VISSIM mikrosimulacijski model. Rezultati pokazuju da parametri kolone vozila trebaju biti u skupu ulaznih parametara koji će ući u postupak kalibracije. Promatrani parametri kolone utječu na propusnu moć raskrižja, a rezultati pokazuju da je potrebno revidirati raspon ulaznih vrijednosti jednog od analiziranih parametara.The calibration process is a basic condition of traffic model application in local conditions. The choice of input parameters, which are used in calibration process, influences the success of the calibration process itself; therefore, the goal is to choose parameters with a larger influence on the modelling process. This paper offers a detailed analysis of car-following input parameters and their influence on the modelled travelling time. The experimental basis was a one-lane roundabout, and the tool used for traffic simulation was the VISSIM microsimulation traffic model. The results show that the car-following input parameters should be a part of the set of input parameters, which will enter the process of calibration. The examined car-following input parameters affect the capacity of intersections and results show that it is necessary to revise the range of input values of one of the observed car-following input parameters

Dynamic load balancing of parallel road traffic simulation

The objective of this research was to investigate, develop and evaluate dynamic load-balancing strategies for parallel execution of microscopic road traffic simulations. Urban road traffic simulation presents irregular, and dynamically varying distributed computational load for a parallel processor system. The dynamic nature of road traffic simulation systems lead to uneven load distribution during simulation, even for a system that starts off with even load distributions. Load balancing is a potential way of achieving improved performance by reallocating work from highly loaded processors to lightly loaded processors leading to a reduction in the overall computational time. In dynamic load balancing, workloads are adjusted continually or periodically throughout the computation. In this thesis load balancing strategies were evaluated and some load balancing policies developed. A load index and a profitability determination algorithms were developed. These were used to enhance two load balancing algorithms. One of the algorithms exhibits local communications and distributed load evaluation between the neighbour partitions (diffusion algorithm) and the other algorithm exhibits both local and global communications while the decision making is centralized (MaS algorithm). The enhanced algorithms were implemented and synthesized with a research parallel traffic simulation. The performance of the research parallel traffic simulator, optimized with the two modified dynamic load balancing strategies were studied

Simulação Microscópica Distribuída de Tráfego

A maioria das grandes cidades do mundo enfrenta problemas de tráfego. Na busca de soluções para os problemas do tráfego surge, como poderosa ferramenta, a simulação, que utiliza técnicas matemáticas, computacionais e estatísticas para representar o tráfego. Modelos de simulação de tráfego podem ser classificados de várias formas. A mais utilizada é quanto ao nível de detalhes com que os modelos representam o mundo real e quanto à maneira como o comportamento dos veículos é reproduzido. Seguindo esta classificação, os modelos podem ser macro, meso ou microscópicos. Modelos microscópicos simulam as entidades do sistema individualmente e com um alto nível de detalhes. Cada par veículo-motorista tem um comportamento próprio e é um componente ativo na simulação. Não somente veículos e motoristas são modelados, mas qualquer outra entidade que possa influenciar no tráfego, como controladores de tráfego, trechos específicos de pistas e incidentes. Modelar o tráfego no nível microscópico representa hoje o estado da arte para os simuladores de tráfego. Quanto mais completo um modelo (as características microscópicas do tráfego são consideradas), mais realista será a simulação. Por outro lado, maior é o esforço computacional necessário para sua execução. Alguns simuladores microscópicos requerem computadores de grande desempenho ou supercomputadores e, conseqüentemente, têm um alto custo. A alternativa ao uso de supercomputadores é a utilização da computação distribuída. Um ambiente distribuído permite que o programa de simulação seja executado em múltiplos processadores de forma paralela e assim obtenha ganhos de desempenho. Usar um ambiente distribuído requer uma estratégia de divisão das tarefas entre processadores e uma solução para sincronizar a execução dessas tarefas. Este trabalho tem como objetivo identificar e implementar uma solução para a execução de um simulador microscópico de tráfego em um ambiente distribuído, disponibilizando uma alternativa de baixo custo para estudo do tráfego

Urban Traffic Simulation With Psycho-Physical Vehicle-Following Models

A psycho-physical vehicle-following model tries to capture both the physical and human components of congested-traffic simulations. These models determine the reactions of the vehicle driver depending on the vehicle's state. The state of a vehicle can be determined by the distance and by the difference in speed, in comparison to the leading vehicle. If the vehicle state changes, the driver must react. The reaction of the driver is to calculate a new value for acceleration. There are two different classical methods of time advance to calculate the state changes. This paper examines the effect of these methods on simulation run times and simulation results. Empirical experiments were done on a SLX-based simulation model