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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Theoretical analysis of the effects of bus operations on urban corridors and networks

Castrillon, Felipe 07 January 2016 (has links)
Bus systems have a large passenger capacity when compared to personal vehicles and thus have the potential to improve urban mobility. However, buses that operate in mixed vehicle traffic can undermine the effectiveness of the road system as they travel at lower speeds, take longer to accelerate and stop frequently to board and alight passengers. In traffic flow theory, buses are known as slow-moving bottlenecks that have the potential to create queue-spillbacks and thus increase the probability of gridlock. Currently, traditional metropolitan transportation planning models do not account for these negative effects on roadway capacity. Also, research methods that study multimodal operations are often simulated or algorithmic which can only provide specific results for defined inputs. The objective of this research is to model and understand the effects of bus operations (e.g., headway, number of stops, number of routes) on system performance (e.g. urban corridor and network vehicular capacity) using a parsimonious analytical approach with a few parameters.The models are built using the Macroscopic Fundamental Diagram (MFD) of traffic which provides aggregate measures of vehicle density and flow. Existing MFD theory, which accounts for corridors with only one vehicle class are extended to include network roadway systems and bus operations. The results indicate that buses have two major effects on corridors: the moving bottleneck and the bus short-block effect. Also, these corridor effects are expanded to urban networks through a vehicle density-weighted average. The models have the potential to transform urban multimodal operations and management as they provide a simple tool to capture aggregate performance of transportation systems.
2

Controlling Traffic With Moving Bottlenecks

Svensson, André, Lenart, Gustav January 2020 (has links)
Traffic shockwaves are a regularly occurring phe-nomenon in traffic that are a source of irritation and delaysfor the road users. One type of shockwave is the stop-and-gowave which forces entering drivers to stop and advance slowlyuntil the wave is passed. This project aims to design a controlalgorithm through the use of models and simulations to increasethe rate at which a stop-and-go wave dissipates. To design themodel and algorithm the Simulation of Urban MObility (SUMO)simulator and the Traffic Control Interface (TraCI) were usedin conjunction with Python. The setup used for simulation wasthat of a one way, two lane highway with an artificially inducedstop-and-go wave.The designed algorithm manages to dissipate a stop-and-go wavecompletely without introducing new ones. / Trafikvågorär ett vanligt förekommandefenomen i trafiken vilketär en orsak till frustration ochförseningar. En typ av vågär startochstop vågen som tvingarförare att stanna och långsamt fortsätta genom vågen tills denpasserat. Målet med detta projektär att utveckla en kontrol-lalgoritm med hjälp av modeller och simuleringar för attökaavtagandet av en sådan våg. För att utveckla modellen ochalgoritmen används simulatorn Simulation of Urban MObility(SUMO) och Traffic Control Interface (TraCI) i kombinationmed programmeringsspråket Python. Simulering gjordes på ettnätverk bestående av en enkelriktad, tvåfilig motorväg med enkonstgjord startochstop våg.En algoritm utvecklades som kan skingra en startochstop vågutan att skapa nya. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

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