Semi-automated modeling approaches to route selection in GIS

As an alternative to traditional graphical intuitive approaches (GIA), a semi-automated modeling approach (SMA) can more efficiently identify linear routes by using powerful iterative and automated methods. In this research, two case studies were investigated to examine critical issues relating to the accuracy and effectiveness of raster-defined algorithmic approaches to linear route location. The results illustrate that different shortest-path algorithms do not necessarily result in markedly different linear routes. However, differing results can occur when using different neighboring-cell links in the cell-based route network construction. Cell-based algorithmic approaches in both Arc/Info and IDRISI software generate very similar results which are comparable to linear modeling with greater than eight neighboring-cell links. Given a specific shortest-path algorithm and its route searching technique, the use of a finer spatial resolution only results in a narrower and smoother route corridor. Importantly, cost surface models can be generated to represent differing cumulative environmental \u27costs\u27 or impacts in which different perceptions of environmental cost can be simulated and evaluated.;Three different simulation techniques comprising Ordered Weighted Combination models (OWC), Dynamic Decision Space (DDS), and Gateway-based approaches, were used to address problems associated with concurrent and dynamic changes in multi-objective decision space. These approaches provide efficient and flexible simulation capability within a dynamic and changing decision space. When aggregation data models were used within a Gateway approach the match of resulting routes between GIA and SMA analyses is close. The effectiveness of SMA is greatly limited when confronted by extensive linear and impermeable barriers or where data is sparse. Overall, achieving consensus on environmental cost surface generation and criteria selection is a prerequisite for a successful SMA outcome. It is concluded that SMA has several positive advantages that certainly complement a GIA in linear route siting and spatial decision-making

Vektori- ja rasteriaineistojen yhdistäminen kustannuspinnaksi reitinetsintää varten

Alhaisimman kustannuksen reitin etsintä on paikkatietoanalyysi, jolla pyritään selvittämään edullisin mahdollinen kustannus kustannuspinnan kohteiden välillä. Perinteisesti paikkatieto-ohjelmissa analyysi on toteutettu siten, että kustannuspinta mallinnetaan rasterina, jossa jokainen solun arvo kuvaa kustannusta liikkua kyseisen solun alueella. Kustannuspinnan mallintamiselle on rasterin lisäksi olemassa useita muitakin vaihtoehtoja, kuten kustannusviivat ja polygonit. Eri tavat mallintaa kustannuspintaa soveltuvat käytettäväksi erilaisten aineistojen kanssa, mutta mikään tavoista ei sovellu hyvin käytettäväksi kaiken tyyppisten aineistojen kanssa. Tässä työssä esitetään menetelmä, jolla eri aineistotyyppejä voidaan yhdistää yhdeksi kustannuspinnaksi ja muodostaa siitä yhtenäinen verkko reitinetsintää varten. Esitelty menetelmä hyödyntää kuudentoista naapurin menetelmää rasteriaineistoissa ja näkyvyysverkkoon perustuvaa menetelmää aluemaisten vektorikohteiden osalta. Työssä esitellään kuinka erityyppisten aineistojen yhdistäminen yhdeksi verkoksi tehdään teoriatasolla, selvitetään kuinka tämä verkonmuodostus saadaan tehtyä tehokkaasti käytännön sovelluksessa ja testataan algoritmin toimintaa käytännön tapaustutkimuksen kautta. Kehitetty menetelmä todettiin tapaustutkimuksessa käyttökelpoiseksi ja sen havaittiin mahdollistavan entistä monimutkaisempien kulkukustannukseen vaikuttavien ilmiöiden mallintamisen käyttäen tavanomaisia paikkatietoaineistoja. Kehityskohteita havaittiin liittyen algoritmin tehokkuuteen, tarkkuuteen ja algoritmin vaatiman kustannuspinnan muodostamisen helppouteen. Useisiin havaituista kehityskohteista esitetään mahdollisia ratkaisuvaihtoehtoja, joiden käytännön toteutus jätettiin kuitenkin jatkotutkimuksen kohteeksi

Development of a spatial sugarcane transport infrastructure-planning model.

Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.Due to the significant cost of transport in the sugar industry, a model, named FastTrack, was developed to investigate infrastructure planning opportunities. The model mathematically incorporates road construction and maintenance costs, terrain and land-use maps, vehicle performance specifications and annual sugarcane volumes to determine the most cost effective route, per vehicle type, from a production region to a mill. Route planning using geographical information systems (GIS) is a standard approach for determining the optimum alignment for pipelines, roads and canals. Theory of this approach was reviewed to create a foundation for the development of FastTrack. A small portion of the Noodsberg sugar mill region in the KwaZulu-Natal midlands was selected as a case study area to test the capabilities of FastTrack. A start location was identified as a natural flow point for 70 000 tons of sugarcane hauled from an area south of the mill. Currently this volume is transported along a 9.3 km stretch of national road from the start location to the sugar mill, while the Euclidean distance is approximately 7 km. Three vehicle types, differing in payload, fuel consumption and road speed were assessed. Two common and currently utilised vehicles, the tractor hilo and interlink combinations, were aligned by FastTrack along existing national roads. A financial penalty for driving on national roads was assumed for the third vehicle type considered, land trains, as these are currently not permitted to operate on national roads in South Africa. This high bulk vehicle was selected to test the capabilities of FastTrack and to identify if cost savings could be realised through increased consignment capacity as has been achieved in Australia, Malawi and Brazil. Utilising the model a new and more direct theoretical route was generated for the land train with a length of 7.4 km. Existing farm roads which would require upgrading made up 34 % of this proposed route. An economic analysis was conducted and showed that under current conditions, the private route generated by FastTrack for land train use, would be the most cost effective, with a system cost of R 57.50 t" . The tractor hilo and interlink had system costs of R 59.58 t" and R 60.98 t"1 respectively. Repeating the economic analysis with projected fuel prices indentified that the cost saving advantage of the land train system over the other two vehicle configurations increases with increasing fuel costs. A rigorous validation process, including a sensitivity analysis of results from FastTrack, revealed that the model performs predictably under a wide range of input conditions and could be a valuable tool for decision making in the sugar industry. However, further research is required to combine more economic and logistical aspects into FastTrack and to increase its usability

Development of a spatial sugarcane transport infrastructure-planning model.

Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.Due to the significant cost of transport in the sugar industry, a model, named FastTrack, was developed to investigate infrastructure planning opportunities. The model mathematically incorporates road construction and maintenance costs, terrain and land-use maps, vehicle performance specifications and annual sugarcane volumes to determine the most cost effective route, per vehicle type, from a production region to a mill. Route planning using geographical information systems (GIS) is a standard approach for determining the optimum alignment for pipelines, roads and canals. Theory of this approach was reviewed to create a foundation for the development of FastTrack. A small portion of the Noodsberg sugar mill region in the KwaZulu-Natal midlands was selected as a case study area to test the capabilities of FastTrack. A start location was identified as a natural flow point for 70 000 tons of sugarcane hauled from an area south of the mill. Currently this volume is transported along a 9.3 km stretch of national road from the start location to the sugar mill, while the Euclidean distance is approximately 7 km. Three vehicle types, differing in payload, fuel consumption and road speed were assessed. Two common and currently utilised vehicles, the tractor hilo and interlink combinations, were aligned by FastTrack along existing national roads. A financial penalty for driving on national roads was assumed for the third vehicle type considered, land trains, as these are currently not permitted to operate on national roads in South Africa. This high bulk vehicle was selected to test the capabilities of FastTrack and to identify if cost savings could be realised through increased consignment capacity as has been achieved in Australia, Malawi and Brazil. Utilising the model a new and more direct theoretical route was generated for the land train with a length of 7.4 km. Existing farm roads which would require upgrading made up 34 % of this proposed route. An economic analysis was conducted and showed that under current conditions, the private route generated by FastTrack for land train use, would be the most cost effective, with a system cost of R 57.50 t" . The tractor hilo and interlink had system costs of R 59.58 t" and R 60.98 t"1 respectively. Repeating the economic analysis with projected fuel prices indentified that the cost saving advantage of the land train system over the other two vehicle configurations increases with increasing fuel costs. A rigorous validation process, including a sensitivity analysis of results from FastTrack, revealed that the model performs predictably under a wide range of input conditions and could be a valuable tool for decision making in the sugar industry. However, further research is required to combine more economic and logistical aspects into FastTrack and to increase its usability

Structuring a Wayfinder\u27s Dynamic and Uncertain Environment

Wayfinders typically travel in dynamic environments where barriers and requirements change over time. In many cases, uncertainty exists about the future state of this changing environment. Current geographic information systems lack tools to assist wayfinders in understanding the travel possibilities and path selection options in these dynamic and uncertain settings. The goal of this research is a better understanding of the impact of dynamic and uncertain environments on wayfinding travel possibilities. An integrated spatio-temporal framework, populated with barriers and requirements, models wayfinding scenarios by generating four travel possibility partitions based on the wayfinder\u27s maximum travel speed. Using these partitions, wayfinders select paths to meet scenario requirements. When uncertainty exists, wayfinders often cannot discern the future state of barriers and requirements. The model to address indiscemibility employs a threevalued logic to indicate accessible space, inaccessible space, and possibly inaccessible space. Uncertain scenarios generate up to fifteen distinct travel possibility categories. These fifteen categories generalize into three-valued travel possible partitions based on where travel can occur and where travel is successful. Path selection in these often-complex environments is explored through a specific uncertain scenario that includes a well-defined initial requirement and the possibility of an additional requirement somewhere beforehand. Observations from initial path selection tests with this scenario provide the motivation for the hypothesis that paths arriving as soon as possible to well-defined requirements also maximize the probability of success in meeting possible additional requirements. The hypothesis evaluation occurs within a prototype Travel Possibility Calculator application that employs a set of metrics to test path accessibility in various linear and planar scenarios. The results did not support the hypothesis, but showed instead that path accessibility to possible additional requirements is greatly influenced by the spatio-temporal characteristics of the scenario\u27s barriers

The desertification context

Desertification is a critical issue for Mediterranean drylands. Climate change is expected to aggravate its extension and severity by reinforcing the biophysical driving forces behind desertification processes: hydrology, vegetation cover and soil erosion. The main objective of this thesis is to assess the vulnerability of Mediterranean watersheds to climate change, by estimating impacts on desertification drivers and the watersheds’ resilience to them. To achieve this objective, a modeling framework capable of analyzing the processes linking climate and the main drivers is developed. The framework couples different models adapted to different spatial and temporal scales. A new model for the event scale is developed, the MEFIDIS model, with a focus on the particular processes governing Mediterranean watersheds. Model results are compared with desertification thresholds to estimate resilience. This methodology is applied to two contrasting study areas: the Guadiana and the Tejo, which currently present a semi-arid and humid climate. The main conclusions taken from this work can be summarized as follows: • hydrological processes show a high sensitivity to climate change, leading to a significant decrease in runoff and an increase in temporal variability; • vegetation processes appear to be less sensitive, with negative impacts for agricultural species and forests, and positive impacts for Mediterranean species; • changes to soil erosion processes appear to depend on the balance between changes to surface runoff and vegetation cover, itself governed by relationship between changes to temperature and rainfall; • as the magnitude of changes to climate increases, desertification thresholds are surpassed in a sequential way, starting with the watersheds’ ability to sustain current water demands and followed by the vegetation support capacity; • the most important thresholds appear to be a temperature increase of +3.5 to +4.5 ºC and a rainfall decrease of -10 to -20 %; • rainfall changes beyond this threshold could lead to severe water stress occurring even if current water uses are moderated, with droughts occurring in 1 out of 4 years; • temperature changes beyond this threshold could lead to a decrease in agricultural yield accompanied by an increase in soil erosion for croplands; • combined changes of temperature and rainfall beyond the thresholds could shift both systems towards a more arid state, leading to severe water stresses and significant changes to the support capacity for current agriculture and natural vegetation in both study areas.Supported by the Portuguese Foundation for Science and Technology and the European Union under Operational Program “Science and Innovation” (POCI 2010), Ph.D. grant ref. SFRH/BD/5059/200

Análisis geoespacial para la caracterización funcional de las infraestructuras viarias en modelos de accesibilidad territorial utilizando sistemas de información geográfica

[Resumen] La aplicación de los Sistemas de Información Geográfica (SIG) sobre las infraestructuras viarias representa un importante reto en la ingeniería civil actual y del futuro. Bajo la teoría personal que defendemos en este proyecto, de que cualquier dato o saber manejado por el hombre es susceptible de representarse sobre la superficie terrestre, los SIG se convierten en un magnífico instrumento para aumentar el conocimiento humano sobre cualquier realidad. Las nuevas tecnologías ofrecen múltiples posibilidades para aportar datos a los SIG en cualquier campo, y por supuesto sobre las características y el funcionamiento de las carreteras. Pero se requieren nuevos enfoques, planteamientos y metodologías para tratar adecuadamente los datos viarios, y conseguir análisis más completos para una gestión más eficiente de estas infraestructuras. Esta tesis doctoral propone un método para realizar una parametrización mediante geometría de secuencia de puntos, que permite caracterizar todas las variables técnicas y funcionales que afectan o influyan sobre una infraestructura territorial de trazado lineal, en general, y particularmente sobre una red de carreteras. Gracias a la versatilidad que proporciona este método es posible asignar multitud de parámetros a cada sección del viario, provenientes de distintas fuentes de datos a través de diferentes tecnologías, y tratarlos convenientemente para generar nueva información a partir de ellos. También se permite realizar simplificaciones geométricas de la información mediante la tramificación temática según los aspectos que se necesite, para que pueda manejarse con mayor facilidad sobre los SIG, y ejecutar sobre esos datos diferentes métodos de análisis geoespacial. La funcionalidad de la red viaria puede analizarse desde múltiples perspectivas, pero sin duda una de las más eficientes y recomendables es mediante el cálculo de la accesibilidad que proporcionan las carreteras en un determinado territorio. Aunque existen gran variedad de modelos de cálculo de accesibilidad, el algoritmo de Coste Distancia basado en superficies de costes acumulados, se presenta como uno de los más interesantes sobre SIG, debido a la facilidad para incorporar datos al modelo ráster, y a que obtiene resultados de accesibilidad en cualquier lugar del ámbito geográfico analizado. Sin embargo su operativa de cálculo limita la aplicación de este algoritmo cuando se dispone de modos de desplazamiento especializados con limitación de accesos, como por ejemplo ocurre en vías de alta capacidad o prestaciones como autopistas, autovías, etc. En esta tesis doctoral se proponen dos métodos para superar esta limitación, mediante la Suma de Costes Parciales y con el algoritmo Coste Distancia Condicionado. Este último, además de conseguir modelar con gran fiabilidad cualquier modo transporte sobre la superficie terrestre, ofrece nuevas posibilidades de análisis sobre los modelos ráster gracias a la aplicación de restricciones condicionadas en los cálculos a ejecutar entre celdas vecinas. Las aplicaciones prácticas realizadas durante la investigación, de estos métodos, tanto la parametrización mediante geometrías de puntos, como los dos nuevos modelos de accesibilidad, muestran su grado de validez y eficacia para el análisis geoespacial de las infraestructuras viarias.[Resumo] A aplicación dos Sistemas de Información Xeográfica (SIX) sobre as infraestructuras viarias representa un importante reto na enxeñería civil actual e futura. Baixo a teoría persoal que defendemos neste proxecto, de que calquera dato ou saber manexado polo home é susceptible de representarse sobre a superficie terrestre, os SIX convértense nun magnífico instrumento para aumentar o coñecemento humano sobre calquera realidade. As novas tecnoloxías ofrecen múltiples posibilidades para aportar datos aos SIG en calquera campo, e por suposto sobre as características e o funcionamento das estradas. Pero requírense novos enfoques, formulacións e metodoloxías para tratar adecuadamente os datos viarios, e conseguir análises máis completas para unha xestión máis eficiente destas infraestructuras. Esta tese de doutorado propón un método para realizar unha parametrización mediante xeometría de secuencia de puntos, que permite caracterizar todas as variables técnicas e funcionales que afecten ou inflúan sobre unha infraestructura territorial de trazado lineal, en xeral, e particularmente sobre unha rede de estradas. Gracias á versatilidade que proporciona este método é posible asignar multitude de parámetros a cada sección do viario, provintes de distintas fontes de datos a través de diferentes tecnoloxías, e tratalos convenientemente para xerar nova información a partir deles. Tamén se permite realizar simplificacións xeométricas da información mediante a tramificación temática segundo os aspectos que se necesite, para que poida manexarse con maior facilidade sobre os SIX, e executar sobre eses datos diferentes métodos de análise xeoespacial. A funcionalidade da rede viaria pode analizarse desde múltiples perspectivas, pero sen dúbida una das máis eficientes e recomendables é mediante o cálculo da accesibilidade que proporcionan as estradas nun determinado territorio. Aínda que existen gran variedade de modelos de cálculo de accesibilidade, o algoritmo de Custo Distancia baseado en superficies de custos acumulados, preséntase como un dos máis interesantes sobre SIX, debido á facilidade para incorporar datos ao modelo ráster, e a que obtén resultados de accesibilidade en calquera lugar do ámbito xeográfico analizado. Con todo a súa operativa de cálculo limita a aplicación deste algoritmo cando se dispón de modos de desprazamento especializados con limitación de accesos, como por exemplo ocorre en vías de alta capacidade ou prestacións como autoestradas, autovías, etc. Nesta tese de doutoramento propóñense dous métodos para superar esta limitación, mediante a Suma de Custos Parciais e co algoritmo de Custo Distancia Condicionado. Este último, ademáis de conseguir modelar con gran fiabilidade calquera modo transporte sobre a superficie terrestre, ofrece novas posibilidades de análises sobre os modelos ráster gracias á aplicación de restriccións condicionadas nos cálculos a executar entre celas veciñas. As aplicacións prácticas realizadas durante a investigación, destes métodos, tanto a parametrización mediante xeometrías de secuencia de puntos, como os dous novos modelos de accesibilidade, mostran o seu grado de validez e eficacia para a análise xeoespacial das infraestructuras viarias.[Abstract] Application of Geographic Information Systems (GIS) on road infrastructure represents a major challenge in civil engineering of today and tomorrow. Under the personal theory that I defend in this project, namely that any data or knowledge handled by humans is likely to be represented over Earth’s surface, the GIS becomes a great tool for increasing human knowledge of any reality. New technologies offer many opportunities to provide GIS data in any field, and of course on the features and operation of the roads. But, new approaches, proposals and methodologies are needed to properly treat road data and get best analysis for a more efficient management of these infrastructures. This dissertation proposes a method to perform a parametrization using a sequence of points to characterize all technical and operating variables that affect or influence on a linear path infrastructure, in general, and particularly on a road network. Thanks to the versatility provided by this method it is possible to assign multiple parameters to each road section, from different data sources through different technologies, and treat them accordingly to generate new information from them. It also allows geometric simplifications of the information by connecting the dots on thematic stretchs, so it could be more easily handled on GIS, to run on these data different spatial analysis. Functionality of the road network can be analyzed from multiple perspectives, but certainly one of the most efficient and recommended is by calculating the accessibility provided by the roads in a given territory. Although there are a variety of methods for accessibility calculations, Cost Distance algorithm based on accumulated cost surfaces, is presented as one of the most interesting on GIS, because it is ease to incorporate raster data to the model, and because it gets results anywhere of the geographic region analyzed. However, its calculation method limits the application of this algorithm when there are specialized travel modes with limited access, such as occurs in high capacity roads. In this thesis, two methods are proposed to overcome this limitation by means of Partial Costs Sum algorithm and by means of Conditional Cost Distance algorithm. The latter, models with high reliability any transport mode on the surface, and offers new possibilities for analysis of raster models by applying conditional constraints to perform calculations between neighboring cells. Practical applications made during the investigation of these methods, parameterization by means sequence of points, and the two new models of accessibility, show their degree of validity and effectiveness for geospatial analysis of road infrastructure

A genetic algorithm for designing optimal patch configurations in GIS

Geographical Information Systems (GIS) are used for several types of spatial planning but so far they have not been used for optimal patch design. Optimal patch design is a generic spatial problem in which the objective is to design spatially explicit landuse maps when both the composition and configuration of patches are important criteria. There are many applications in conservation, forestry management, watershed management and the management of large military estates. This thesis describes a new autonomous computer program, the genetic algorithm for optimal patch design (GAPD). GAPD combines four components: a genetic search algorithm, a parameterised region growing (PRG) program, raster GIS measurement functions and multi-criteria decision-making methods. The key component is the PRG which translates between the aspatial domain of the search algorithm and the spatial domain of the GIS. GAPD generates landuse maps that optimise the configuration and composition of patches to meet multiple objectives for a given set of input maps and criteria. The theories of landscape ecology are used to establish a framework for formulating optimal patch design problems. The thesis describes the conceptual design of GAPD and its implementation and test, first as a prototype for solving single patch problems and then as a fully functional system for solving multi-objective multi-patch problems. The feasibility of GAPD was established by investigations of issues concerning the representation and measurement of configuration in raster data structures and by testing the efficiency and effectiveness of GAPD with simple problems. GAPD was further evaluated in five hypothetical problems designed to cover a range of different scenarios. The results are promising and show that GAPD has potential as a decision support tool. The final section recommends a number of topics for further research covering technical developments of GAPD, the application of GAPD to real problems and investigations of general issues of optimal patch design