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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

Modeling Lane-based Traffic Flow In Emergency Situations In The Presence Of Multiple Heterogeneous Flows

Saleh, Amani 01 January 2008 (has links)
In recent years, natural, man-made and technological disasters have been increasing in magnitude and frequency of occurrence. Terrorist attacks have increased after the September 11, 2001. Some authorities suggest that global warming is partly the blame for the increase in frequency of natural disasters, such as the series of hurricanes in the early-2000's. Furthermore, there has been noticeable growth in population within many metropolitan areas not only in the US but also worldwide. These and other facts motivate the need for better emergency evacuation route planning (EERP) approaches in order to minimize the loss of human lives and property. This research considers aspects of evacuation routing never before considered in research and, more importantly, in practice. Previous EERP models only either consider unidirectional evacuee flow from the source of a hazard to destinations of safety or unidirectional emergency first responder flow to the hazard source. However, in real-life emergency situations, these heterogeneous, incompatible flows occur simultaneously over a bi-directional capacitated lane-based travel network, especially in unanticipated emergencies. By incompatible, it is meant that the two different flows cannot occupy a given lane and merge or crossing point in the travel network at the same time. In addition, in large-scale evacuations, travel lane normal flow directions can be reversed dynamically to their contraflow directions depending upon the degree of the emergency. These characteristics provide the basis for this investigation. This research considers the multiple flow EERP problem where the network travel lanes can be reconfigured using contraflow lane reversals. The first flow is vehicular flow of evacuees from the source of a hazard to destinations of safety, and the second flow is the emergency first responders to the hazard source. After presenting a review of the work related to the multiple flow EERP problem, mathematical formulations are proposed for three variations of the EERP problem where the objective for each problem is to identify an evacuation plan (i.e., a flow schedule and network contraflow lane configuration) that minimizes network clearance time. Before the proposed formulations, the evacuation problem that considers only the flow of evacuees out of the network, which is viewed as a maximum flow problem, is formulated as an integer linear program. Then, the first proposed model formulation, which addresses the problem that considers the flow of evacuees under contraflow conditions, is presented. Next, the proposed formulation is expanded to consider the flow of evacuees and responders through the network but under normal flow conditions. Lastly, the two-flow problem of evacuees and responders under contraflow conditions is formulated. Using real-world population and travel network data, the EERP problems are each solved to optimality; however, the time required to solve the problems increases exponentially as the problem grows in size and complexity. Due to the intractable nature of the problems as the size of the network increases, a genetic-based heuristic solution procedure that generates evacuation network configurations of reasonable quality is proposed. The proposed heuristic solution approach generates evacuation plans in the order of minutes, which is desirable in emergency situations and needed to allow for immediate evacuation routing plan dissemination and implementation in the targeted areas.
2

Reversibla 2+1-fält på motortrafikled Utvärdering av restidseffekter för Värmdöpendlare : Utvärdering av restidseffekter för Värmdöpendlare / Reversible 2+1 lanes on motorways : Evaluation of travel time effects for Värmdö commuter.

JOHANSSON, JOSEFIN January 2023 (has links)
Värmdö is a commuter municipality to Stockholm. Road 222 between Värmdö and Stockholm is the main commuter route for both bus and car traffic. Road 222 is a bottleneck at Farstabron in the direction towards Värmdö, where the motorway will go from two to one lane and become a non-meeting motorway. Towards Stockholm, the bridge has two lanes, which is why capacity is not affected as strongly in that direction. The accessibility problems arise mainly in the direction of Värmdö during maximum hours in the afternoon and during weekends and summer time as the municipality also has many holiday homes. Measures to improve accessibility have been raised by both the municipality and the Swedish Transport Administration. Building a new bridge is not relevant as the remaining expected technical life of the bridge is long. The Swedish Transport Administration has an idea for a reversible lane solution on the bridge, which is the proposal studied in this thesis. Data collection and traffic analysis has been performed to study how the travel time effect would be if Farstabron was rebuilt into a reversible 2 + 1 road, with or without a reversible bus lane. The tool used is the microsimulation program PTV VISSIM. The results show that a reversible solution without a bus lane is the alternative that provides by far the largest travel time gains for both car and bus in 2040. The degree project contains a chapter that deals with traffic engineering theory and traffic simulation theory as well as a literature study chapter that summarizes the knowledge about reversible lanes. The information about reversible lanes, even international studies, is poor.Experiences of reversible lanes is good and is mainly to be recommended as the flow in one direction is significantly greater than in the other. The traffic safety risk is primarily linked to unprotected road users. The most common internationally according to what has been identified is to implement reversible lanes on motorways with protective barriers. However, no reversible lane without a barrier have been identified holding 80km/h. Studies have shown that reversible lanes could have a cost-benefit ratio of around 7, which means that the benefit outweighed the costs 7 times in money measured. The weaving dynamics of VISSIM from two to one lane were challenging to calibrate against the reality. Preparatory behavior during lane changes is mainly affected by car-following and lane-changing models in VISSIM. In the simulation the correlation with collected data was slightly more accurate with the car following model for W99 (freeway) rather than W74 (weaving urban rd).

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