The purpose of this dissertation is to develop models and solution approaches to identify the critical hierarchies of railroad and surface transportation network infrastructures, and to facilitate re-routing options that will be necessary for traffic management decision makings in the event of a disaster. We focus on building mathematical models for routing/re-routing of traffic considering the congestion effects which are obvious in the disrupted networks due to disaster. Based on these models, the critical hierarchies of infrastructures are determined. For railroad, we develop two different models: the first one considers ‘unit’ train re-routing and the other one considers Train Design approach. For intermodal system, the optimization model facilitates optimal re-routing of traffic using three surface transportation modes: highway, railway and waterway, considering the congestion characteristics of each mode. For the first model of railroad routing, the optimization model optimally routes unit trains based on a minimum cost network flow formulation with nonlinear objective function. The nonlinear objective function is approximated with a piece-wise linear function to make the model computationally tractable. The second model, known as Train Design optimization, is a highly combinatorial and complex optimization problem. The developed model’s computational complexity suggests us to use heuristic solution procedures. We develop a special heuristic algorithm to route the traffic in the congested network. In this heuristic procedure, we divide the problem into two sub-problems (SPs): SP-1 is termed as Block-to-Train Assignment (BTA) problem, and SP-2 is termed as Train Routing (TR) problem. BTA problem provides a feasible solution that includes the minimum number of required trains with the pick-up and drop-off points of the blocks carried by these trains, and TR problem ensures the optimal routing of these trains. Similar to railroad, an optimization model is developed for optimal routing/rerouting of traffic using the intermodal network. It is a mixed integer programming (MIP) problem, which is not practical to solve for real-world problem instances within reasonable amount of time. Linear relaxation to this model provides a very good lower bound closer to optimal solution. Therefore, we implemented our case-study for a realworld intermodal transportation system of five U.S. states.

Congestion on the road is identified as a severe threat to nations’ economy. To address this problem, in the past the capacity of existing infrastructure is increased by building new roads. But as history has shown, it is not only an expensive and unsustainable, but also not an efficient way of dealing with this problem. Alternatively, by identifying underutilized links, for example, in the form of parallel routes, the already existing infrastructure can often be used more efficient. This thesis focuses on the development of a framework to simulate re-routing incentives to enable an improved travel corridor performance. Thus, the effects of providing traveler information and tendering mometary incentives on a concidor’s traffic flow are investigated. The aim is to show that by changing the route choice behavior of a certain percentage of the fleet, the overall performance of the existing corridor can be increased. By using the microscopic traffic simulation tool VISSIM in combination with dynamic traffic modeling, numerous scenarios are simulated. By gradually increasing the amount of users who get access to the incentive scheme, the impacts of the penetration get analyzed as well. Based on a network stretch located in California, United States, the simulation model is developed. Using this model, three different scenarios are investigated in detail: a No Incident scenario, a Construction Work scenario and an Accident scenario. Finally, a comprehensive analysis of the simulation results takes place. It mainly focuses on the indicator travel time to discuss the impacts on the corridor performance. Interpreting the achieved simulation results, it can be stated that already small penetration rates have the potential for a significant increase of the corridor performance. To be able to optimize the corridor’s performance, free capacity on detours – especially  at bottlenecks like ramps – has to be available. Nevertheless, in case of high penetration rates, straightforward broadcasting of incentives is not an option.

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: MPLS-based recovery is intended to effect rapid and complete restoration of traffic affected by a fault in a Multiprotocol Label Switching (MPLS) network. Two MPLS-based recovery models have been proposed: lP re-routing which establishes recovery paths on demand, and protection switching which works with pre-established recovery paths. lP re-routing is robust and frugal since no resources are pre-committed but it is inherently slower than protection switching which is intended to offer high reliability to premium services where fault recovery takes place at the 100 ms time scale. This thesis presents an overview of various recovery techniques and addresses the problem of how to find an in some sense optimal set of pre-established traffic engineered recovery paths, given a network with link capacities and traffic demands. We present and motivate our choice of a nonlinear objective function and optimization method for finding traffic engineered working and recovery paths. A variant of the flow deviation method is used to find and capacitate a set of optimal label switched paths. We present and evaluate two simple methods for computing a set of pre-established traffic engineered recovery paths by using the flow deviation method. / AFRIKAANSE OPSOMMING: MPLS-gebaseerde herstel is daarop gemik om verkeer wat deur 'n fout in 'n Multiprotokol Etiketwisseling (Multiprotocol Label Switching) (MPLS) netwerk geaffekteer is, vinnig en volledig te herstel. Twee MPLS-gebaseerde herstelmodelle is voorgestel: Internetprotokol-herroetering (lP rerouting) wat herstelpaaie op aanvraag tot stand bring, en beskermingsoorskakeling (protection switching) wat met voorafbeplande herstelpaaie werk. IP-herroetering is robuust en voordelig aangesien geen netwerkbronne vooraf gereserveer word nie, maar dit is inherent stadiger as beskermingsoorskakeling wat veronderstel is om 'n hoë graad van betroubaarheid aan belangrike dienste te bied waar die herstel van foute in die 100 ms tydskaal plaasvind. Hierdie tesis verskaf 'n oorsig oor verskeie hersteltegnieke en ondersoek die probleem hoe om 'n optimale versameling van voorafbeplande herstelpaaie te vind, gegee 'n netwerk met skakelkapasiteite (link capacities) en verwagte netwerkverkeer. Ons stel voor en motiveer ons keuse van 'n nie-lineêre objekfunksie en optimeringsmetode om verkeersontwerpde (traffic engineered) aktiewe en herstelpaaie te vind. 'n Variant van die vloeideviasie (flow deviation)-metode word gebruik om 'n optimale versameling van etiketwisseling (label switched) paaie te vind en om 'n optimale hoeveelheid kapasiteit aan die paaie toe te ken. Ons stel voor en evalueer twee eenvoudige metodes om 'n versameling van optimale voorafbeplande herstelpaaie te bereken deur die vloeideviasie-metode toe te pas.

The planning of snow removal routes is complicated by the fact that the amount it snows, and thus the amount of resources, that is, vehicles, needed to clear it, varies from year to year. This variation has created a demand for a way to quickly generate efficient snow removal plans that take the resources that are available into account. In this report we describe the development of an ad hoc heuristic algorithm that improves already existing feasible solutions to the snow removal problem. It accomplishes this by reassigning tasks from the vehicles with the longest tours to those with the shortest tours, followed by reordering their tasks to ensure that the solution remains feasible. This algorithm is meant to be implemented in a larger piece of software and it is tested on a set of pre-generated solutions for a given network and number of vehicles, including the best known ones. Over half of the previously best known solutions were improved by this algorithm.

Water is an essential element for life and crucial to survival. South Africa is a semi-arid country and therefore water should be protected and managed effectively by all residents of the country. In the 1830s the Mooi River was the key reason for the Voortrekkers to establish Potchefstroom at a locality adjacent to this river. The Voortrekkers noticed the dolomitic outcroppings in the vicinity, but still opted to reside next to the river for it provided easily accessible water and fertile soil. Since the 1830s water legislation regulating the management and use of the water in the Mooi River has been amended innumerable times to bring us to the current situation of Potchefstroom’s water (mis)management by the role-players and stakeholders of the water source. As a resident of Potchefstroom, the researcher has a keen interest in the origin of the city’s water sources, the re-routing of the water from the origin to the water purification unit via the open-on-top cement canal system, and the overall management of these canals and their servitudes. In order to conduct a research study on the Mooi River’s water re-routing canals and servitudes, the following research methods were applied: The researcher performed a comprehensive literature review, conducted fieldwork, held interviews with landowners and experts in the geographical area of the Mooi River Valley, and performed statistical analyses as well as content analyses of the findings. Some of the most alarming findings include the lack of co-operative governance between water users and – authorities, and the current public management and disaster risk management challenges in the re-routing of water from Klerkskraal Dam down to the water purification plant of Potchefstroom. It is recommended that the major stakeholders of the Mooi River Valley, e.g. the disaster management centre in Potchefstroom, the Department of Water and Sanitation’s (DWS) regional offices in Potchefstroom, as well as the Tlokwe Local Municipality need to join forces for a combined effort to accomplish the overarching research objective of achieving improved cooperative municipal governance and Integrated Water Resources Management (IWRM) to eventually ensure the safe and effective re-routing of water from the Klerkskraal Dam to the Potchefstroom water purification plant. Note: Since July 2014 the Department of Water Affairs (DWA) has changed to the Department of Water and Sanitation (DWS). / MA (Public Management and Governance), North-West University, Potchefstroom Campus, 2015

Water is an essential element for life and crucial to survival. South Africa is a semi-arid country and therefore water should be protected and managed effectively by all residents of the country. In the 1830s the Mooi River was the key reason for the Voortrekkers to establish Potchefstroom at a locality adjacent to this river. The Voortrekkers noticed the dolomitic outcroppings in the vicinity, but still opted to reside next to the river for it provided easily accessible water and fertile soil. Since the 1830s water legislation regulating the management and use of the water in the Mooi River has been amended innumerable times to bring us to the current situation of Potchefstroom’s water (mis)management by the role-players and stakeholders of the water source. As a resident of Potchefstroom, the researcher has a keen interest in the origin of the city’s water sources, the re-routing of the water from the origin to the water purification unit via the open-on-top cement canal system, and the overall management of these canals and their servitudes. In order to conduct a research study on the Mooi River’s water re-routing canals and servitudes, the following research methods were applied: The researcher performed a comprehensive literature review, conducted fieldwork, held interviews with landowners and experts in the geographical area of the Mooi River Valley, and performed statistical analyses as well as content analyses of the findings. Some of the most alarming findings include the lack of co-operative governance between water users and – authorities, and the current public management and disaster risk management challenges in the re-routing of water from Klerkskraal Dam down to the water purification plant of Potchefstroom. It is recommended that the major stakeholders of the Mooi River Valley, e.g. the disaster management centre in Potchefstroom, the Department of Water and Sanitation’s (DWS) regional offices in Potchefstroom, as well as the Tlokwe Local Municipality need to join forces for a combined effort to accomplish the overarching research objective of achieving improved cooperative municipal governance and Integrated Water Resources Management (IWRM) to eventually ensure the safe and effective re-routing of water from the Klerkskraal Dam to the Potchefstroom water purification plant. Note: Since July 2014 the Department of Water Affairs (DWA) has changed to the Department of Water and Sanitation (DWS). / MA (Public Management and Governance), North-West University, Potchefstroom Campus, 2015

Made available in DSpace on 2014-12-17T14:55:05Z (GMT). No. of bitstreams: 1 RicardoKMG.pdf: 620624 bytes, checksum: 2265857dd8185aa481f6e9891ee2c38f (MD5) Previous issue date: 2006-07-11 / The increasing of the number of attacks in the computer networks has been treated with the increment of the resources that are applied directly in the active routers equip-ments of these networks. In this context, the firewalls had been consolidated as essential elements in the input and output control process of packets in a network. With the advent of intrusion detectors systems (IDS), efforts have been done in the direction to incorporate packets filtering based in standards of traditional firewalls. This integration incorporates the IDS functions (as filtering based on signatures, until then a passive element) with the already existing functions in firewall. In opposite of the efficiency due this incorporation in the blockage of signature known attacks, the filtering in the application level provokes a natural retard in the analyzed packets, and it can reduce the machine performance to filter the others packets because of machine resources demand by this level of filtering. This work presents models of treatment for this problem based in the packets re-routing for analysis by a sub-network with specific filterings. The suggestion of implementa- tion of this model aims reducing the performance problem and opening a space for the consolidation of scenes where others not conventional filtering solutions (spam blockage, P2P traffic control/blockage, etc.) can be inserted in the filtering sub-network, without inplying in overload of the main firewall in a corporative network / O aumento do n?mero de ataques a redes de computadores tem sido combatido com o incremento dos recursos aplicados diretamente nos equipamentos ativos de roteamento destas redes. Nesse contexto, os firewalls consolidaram-se como elementos essenciais no processo de controle de entrada e sa?da de pacotes em uma rede. O surgimento dos sistemas detectores de intrus?o (IDS) levou a esfor?os no sentido de incorporar a filtragem de pacotes baseada em padr?es ao firewall tradicional, integrando as fun??es do IDS (como a filtragem baseada em assinaturas, at? ent?o um elemento passivo) ?s fun??es j? existentes no firewall. Em contrapartida ? efici?ncia obtida atrav?s desta incorpora??o no bloqueio de ataques com assinaturas conhecidas, a filtragem no n?vel de aplica??o, al?m de provocar um retardo natural nos pacotes analisados, pode comprometer o desempenho da m?quina na filtragem dos demais pacotes, pela natural demanda por recursos da m?quina para este n?vel de filtragem. Essa tese apresenta modelos de tratamento deste problema, baseados no re-roteamento dos pacotes para an?lise por uma sub-rede de filtragens espec?ficas. A sugest?o de implementa??o deste modelo visa, al?m de amenizar o problema de desempenho supra-citado, abrir espa?o para a consolida??o de cen?rios em que outras solu??es de filtragem n?o convencionais (como ferramentas de bloqueio de SPAM, controle/bloqueio de tr?fego P2P, e outras) possam ser inseridas na sub-rede de filtragem, sem implicar em sobrecarga do firewall principal da rede corporativa