Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The debilitating social, economic and environmental ramifications of traffic congestion are experienced in large cities the world over. The optimisation of traffic signal timings at signalised road intersections attempts to mitigate the extent of these adverse effects of traffic congestion by reducing the delay time experienced by vehicles in a transport network. Today, traffic signal control schemes may be classiffied into one of two main classes, namely fixed-time traffic signal control strategies, which are typically cyclic in nature, and vehicle-actuated traffic signal control strategies, which are typically acyclic in nature. Generally, cyclic control strategies tend to lack exibility, and are unable to adapt to short-term uctuations in traffic ow rates, resulting in green times that are either too long or too short. On the other hand, acyclic control strategies tend to lack coordination between intersections, resulting in vehicles being required to stop at the majority of signalised intersections they encounter. Self-organising traffic signal control has been proposed as an attractive alternative form of control which both exhibits exibility and facilitates a global coordination between intersections as a result of localised signal switching policies. Two examples of existing self-organising traffic signal control algorithms from the literature include an algorithm proposed by Lammer and Helbing in 2008 and an algorithm proposed by Gershenson and Rosenblueth in 2012. These algorithms have been shown to outperform both optimised fixed-time traffc signal control techniques as well as state-of-the-art vehicle actuated trffic signal control techniques, in terms of reducing vehicle delay time in a transport network. A draw-back of both of these self-organising approaches, however, is that their effective operation relies on carefully selected parameter values; poorly selected parameter values may render these algorithms very ineffectual. In this dissertation, three novel self-organising traffic signal traffic control algorithms are proposed. These three algorithms assume the use of existing radar detection sensors mounted at the intersection to provide the necessary input data. The radar detection sensors are capable of detecting and tracking individual vehicles approaching an intersection, providing real-time information pertaining to their physical dimensions, velocities, and ranges from the intersection in terms of both time and distance. The three traffic signal control algorithms are free of any user-specialised parameters, and instead rely solely on the data provided by the radar detection sensors to inform their signal switching policies. The first of these traffic signal control algorithms is inspired by inventory control theory, and draws parallels between the monetary costs typically considered in inventory control models and the delay time costs associated with traffic control at signalised intersections, which the algorithm attempts to minimise. The second novel traffic control algorithm is inspired by the chemical process of osmosis in which solvent molecules move unaided from a region where they are highly concentrated, across a semi-permeable membrane, into a region of high solute molecule concentration. The algorithm models vehicles approaching an intersection as solvent molecules and the physical space available for the vehicles to occupy once they have passed through the intersection as solute molecules. Following this analogy, the intersection is considered to be the semi-permeable membrane. The third traffic control algorithm is a hybrid of the inventory and osmosis-inspired algorithms together with an intersection utilisation maximisation technique, which prevents unnecessary or prolonged underutilisation of an intersection. The three novel trafficc control algorithms, together with the algorithms of Lammer and Helbing, and of Gershenson and Rosenblueth, as well as a fixed-time control algorithm, are implemented in a purpose-built microscopic traffic simulation modelling framework. Several measures are employed to evaluate the relative performances of the algorithms. These measures include the usual mean and maximum resulting delay times incurred by vehicles and the saturation level of the roadways in the transport network, as well as three novel performance measure indicators which include the mean number of stops made by vehicles, their mean normalised delay time and the mean normalised number of stops made. The algorithms are compared in the context of a linear corridor road network topology as well as a grid road network topology under various traffic ow conditions. The overall performance of the novel hybrid traffic signal control algorithm is found to be superior for the corridor road network topology, while the performance of the osmosis-inspired algorithm is found to be superior for the grid road network topology. / AFRIKAANSE OPSOMMING:Die negatiewe sosiale, ekonomiese en omgewingsimpak van verkeersopeenhoping word in groot stede regoor die w^ereld ervaar. Die doel met die optimering van verkeersligwerkverrigting by straatkruisings is om die omvang van hierdie negatiewe impak tee te werk deur die vertraging van voertuie in 'n vervoernetwerk te verminder. Hedendaagse verkeersbeheeralgoritmes kom in een van twee hoofklasse voor, naamlik vaste-tyd beheerstrategiee, wat gewoonlik siklies van aard is, en beheerstrategiee gebaseer op voertuigopsporing, wat tipies asiklies van aard is. Oor die algemeen beskik sikliese beheerstrategiee nie oor genoegsame buigsaambeid om aan te pas by kort-termyn fluktuasies in verkeersvloei nie, wat tipies daartoe lei dat hul groentye spesifiseer wat of te lank of te kort is. Aan die ander kant is asikliese beheerstrategiee nie daartoe in staat om koordinasie tussen naasliggende straatkruisings te bewerkstellig nie, wat weer daartoe lei dat voertuie genoodsaak word om by die oorgrote meerderheid straatkruisings op hul pad te stop. Die self-organiserende beheer van verkeersligte is as 'n aantrektlike, buigsame alternatief voorgestel wat in staat is om globale koordinasie tussen naasliggende straatkruisings as gevolg van gelokaliseerde seinstrategiee te bewerkstellig. Twee voorbeelde van bestaande self-organiserende verkeersbeheeralgoritmes in die literatuur is die algoritmes wat in 2008 deur Lammer and Helbing en in 2012 deur Gershenson en Rosenblueth voorgestel is. Daar is aangetoon dat hierdie algoritmes daartoe in staat is om ge-optimeerde vaste-tyd beheerstrategiee sowel as gevorderde strategiee gebaseer op voertuigopsporing uit te stof in terme van 'n vermindering van die vertraging van voertuie in 'n vervoernetwerk. 'n Nadeel van beide hierdie self-organiserende benaderings is egter dat hul doeltreffende werkverrigting berus op versigtig-gekose parameterwaardes; willekeurige parameterwaardes mag lei na hoogs ondoeltreffende werkverrigitng van die algoritmes. Drie nuwe self-organiserende verkeersbeheeralgoritmes word in hierdie proefskrif voorgestel. Hierdie drie algoritmes maak vir hul toevoerdata staat op die beskikbaarhed van bestaande radar opsporingsensors wat by straatkruisings geinstalleer is. Die sensors is daartoe in staat om individuele voertuie wat 'n straatkruising nader, op te spoor, te volg en intydse data oor hul fisiese dimensies, snelhede, en afstande na die kruising (in terme van beide tyd en afstand) te lewer. Die drie algoritmes bevat geen gebruikers-gespesifiseerde parameters nie, en maak in plaas daarvan slegs gebruik van die sensortoevoerdata om hul beheerstrategiee te bepaal. Die eerste van hierdie verkeersbeheeralgoritmes is deur die teorie van voorraadbeheer geinspireer en maak gebruik van parallelle tussen die monet^ere kostes wat tipies in voorraadbeheermodelle voorkom en die kostes in terme van vertragingstyd wat met verkeersbeheer by straatkruisings aangegaan word, en wat deur die algoritme geminimeer word. Die tweede verkeersbeheeralgoritme is deur die chemiese proses van osmose geinspireer, waar molekules van 'n oplossingsmiddel sonder eksterne hulp vanaf 'n gebied waar hul in hoe konsentrasie voorkom, deur 'n gedeeltelik-deurlaatbare membraan beweeg na 'n gebied waarin hul ook in hoe konsentrasie, maar in opgeloste vorm voorkom. Die algoritme modelleer voertuie wat 'n straatkruising nader as die molekules van die oplossingsmiddel en die fisiese ruimte wat aan die ander kant van die kruising beskikbaar is om deur voertuie beset te word, as molekules in opgeloste vorm. In hierdie analogie word die kruising self as die gedeeltelik-deurlaatbare membraan beskou. Die derde algoritme is 'n hibriede strategie waarin elemente van die eerste twee algoritmes in samewerking met 'n tegniek vir die maksimering van straatkruisingsbenutting gekombineer word, en wat wat ten doel het om onnodige of verlengte onderbenutting van die kruising te vermy. Hierdie drie nuwe verkeersbeheeralgoritmes word, tesame met die bestaande algoritmes van Lammer en Helbing, en van Gershenson en Rosenblueth, asook 'n vaste-tyd beheeralgoritme, in 'n mikroskopiese verkeersimulasiemodelleringsraamwerk wat spesifiek vir die doel ontwerp is, geimplementeer. Verskeie maatstawwe word ingespan om die relatiewe werkverrigting van die algoritmes te evalueer. Hierdie maatstawwe sluit in die gebruiklike gemiddelde en maksimum vertragingstye van voertuie en die versadigingsvlak van strate in die vervoernetwerk, sowel as drie nuwe maatstawwe, naamlik die gemiddelde aantal stoppe deur voertuie, hul genormaliseerde vertragingstye en die gemiddelde, genormaliseerde aantal stoppe. Die algoritmes word in die kontekste van 'n line^ere topologie van opeenvolgende straatkruisings en 'n netwerktopologie van reghoekige straatblokke onder verskeie verkeersdigthede met mekaar vergelyk. Daar word bevind dat die nuwe hibriede algoritme die beste vaar in die line^ere topologie, terwyl die osmose-ge inspireerde algoritme die ander algoritmes uitstof in die straatblok-netwerktopologie.

Inom Jönköpingssocialtjänst genomfördes ett förbättringsarbete som syftade till ökad säkerhet  för  barn  och  unga  samt  förbättrat  stöd  till  barn  och  familjer. Målet  var färre sammanbrott vid placeringar och mer ändamålsenliga insatser i barnets hemmiljö. För att nå syftet genomfördes ett projekt som handlade om att implementera Signs of Safety på ett av Jönköpings socialkontor. Förbättringsarbetet använde Hållbarhetstriangeln och dess tre hörnstenar som struktur; styrning, stöd och störning. Förbättringsarbetet studerades med hjälp av fallstudiedesign som byggde på intervjuer med deltagare i förbättringsprojektet samt dokument. Studiens syfte var att utöka kunskapen kring vilka påverkande faktorer som förekommer kopplat till förbättringsarbete inom socialtjänstens barnavård. Resultatet av förbättringsarbetet visar ingen tydlig förbättring i förhållande till förbättringsarbetets mål, dock indikerar processmätningar att föräldrarna upplever starkare samarbetsallians med socialtjänsten under och efter projektet än före. Studiens resultat tyder på att genomförandet av förbättringsarbetet påverkat förutsättningen att lyckas med implementeringen av Signs of Safety. Följande påverkansfaktorer identifierades: förståelsen, viljan, möjligheten att lära samt fördelningen av resurser. En av studiens slutsatser är att fördelning av resurser verkar vara viktigt men faktorer som är av god kvalitet, såsom metodstöd, kan kompensera för de som saknas vilket styrker tidigare forskning inom området. / The child welfare service in Jönköping municipality carried out an improvement project aimed for increased safety for children and improved support for children and families. The goal was fewer breakdowns in out-of-home placements and more effective interventions in the child's home environment. An improvement project about implementing Signs of Safety in one of Jönköping's offices was conducted.The improvement project was based on the Sustainability Triangle and its three pillars; governance, support and disturbance.The improvement project was studied by case-study design including interviews with participants and document analysis. The aim of the study was to increase the knowledge of influencing factors linked to improvements in the context of child welfare. The goals of the improvement project were not reached though the results indicate that the parents experienced increased collaborative alliance with the social services during and after the project than before.The process of the improvement project influenced the premise of successful implementation of Signs of Safety. Understanding, will, ability to learn and allocation of resources appeared as influencing factors. The conclusion is that allocation of resources seems to be important, but that factors, such as method support, which are of good quality can compensate for missing resources. This reinforces earlier research in the field.

The monitoring of traffic signal systems can be of great importance for identifying problems, self-assessment, budgeting, creating the strategy for future steps, etc. Monitoring procedure was developed through a set of dashboards with relevant signal performance and reliability measures. The dashboards were created to reflect performance and reliability of a specific signal system on a weekly or monthly level. The author used data from ATMS.now signal system central software to illustrate how similar dashboards could be developed from any central software to enable operators to promptly and efficiently monitor various parameters of traffic signals. The main outcome of the study is a pair of Excel dashboards accompanied with appropriate user manual. The dashboards represent the tool for monitoring which can be helpful in the process of evaluation for traffic signal systems. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Signal retiming, or signal optimization process, has not changed much over the last few decades. Traditional procedures rely on low-resolution data and a low-fidelity modeling approach. Such developed signal timing plans always require a fine-tuning process for deployed signal plans in field, thus questioning the very benefits of signal optimization. New trends suggest the use of high-resolution data, which are not easily available. At the same time, many improvements could be made if the traditional signal retiming process was modified to include the use of medium-resolution data and high-fidelity modeling. This study covers such an approach, where a traditional retiming procedure is modified to utilize large medium-resolution data sets, high-fidelity simulation models, and powerful stochastic optimization to develop robust signal timing plans. The study covers a 28-intersection urban corridor in Southeastern Florida. Medium-resolution data are used to identify peak-hour, Day-Of-Year (DOY) representative volumes for major seasons. Both low-fidelity and high-fidelity models are developed and calibrated with high precision to match the field signal operations. Then, by using traditional and stochastic optimization tools, signal timing plans are developed and tested in microsimulation. The findings reveal shortcomings of the traditional approach. Signal timing plans developed from medium-resolution data and high-fidelity modeling approach reduce average delay by 5%-26%. Travel times on the corridor are usually reduced by up to 10.5%, and the final solution does not transfer delay on the other neighboring streets (illustrated through latent delay), which is also decreased by 10%-49% when compared with the traditional results. In general, the novel approach has shown a great potential. The next step should be field testing and validation. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

This paper reviews the effectiveness of vehicle activated signs. Vehicle activated signs are being reportedly used in recent years to display dynamic information to road users on an individual basis in order to give a warning or inform about a specific event. Vehicle activated signs are triggered individually by vehicles when a certain criteria is met. An example of such criteria is to trigger a speed limit sign when the driver exceeds a pre-set threshold speed. The preset threshold is usually set to a constant value which is often equal, or relative, to the speed limit on a particular road segment. This review examines in detail the basis for the configuration of the existing sign types in previous studies and explores the relation between the configuration of the sign and their impact on driver behavior and sign efficiency. Most of previous studies showed that these signs have significant impact on driver behavior, traffic safety and traffic efficiency. In most cases the signs deployed have yielded reductions in mean speeds, in speed variation and in longer headways. However most experiments reported within the area were performed with the signs set to a certain static configuration within applicable conditions. Since some of the aforementioned factors are dynamic in nature, it is felt that the configurations of these signs were thus not carefully considered by previous researchers and there is no clear statement in the previous studies describing the relationship between the trigger value and its consequences under different conditions. Bearing in mind that different designs of vehicle activated signs can give a different impact under certain conditions of road, traffic and weather conditions the current work suggests that variable speed thresholds should be considered instead.

This study investigated the distribution and relation of types of equal signs in middle school. The focus is on interpretations of indices from algebra strand (by grade) in curriculum standards. The researcher used a content analysis method and followed the following procedure. She found all interpretations of indices of the equalities and inequalities signs in middle school. Then, she adopted the way of coding in types of equal signs by McNeil (2006). Data were analyzed quantitatively and qualitatively. There are four findings altogether. First, the higher the grade the more equalities and inequalities related interpretation indices in Algebra Strand. Second, there were most number of equalities and inequalities in four McNeil¡¦s types of equal signs in grade 7 than in the other two grades. Third, the amount of equalities and inequalities in different types of equal signs was not in proportion. Fourth, this distribution provided many opportunities for equal signs to be considered as relational symbols, but yielded various restrictions to students¡¦ development of algebraic concepts. The researcher also made recommendations for future researchers and practitioners: administrative officers, textbook editors, and school teachers.

No description available.

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on August 9, 2009). Includes bibliographical references (p. 96-99).

Syftet med denna uppsats var att undersöka hur motivation diskuteras inom metodenSigns of Safety. För att uppfylla syftet gjordes en kritisk diskursanalys av ett dokumentsom detaljerat presenterade Signs of Safety. Teorier kring makt och empowerment haranvänts för att analysera uppsatsens empiriska material. Vi var främst intresserade attstudera hur materialet diskuterar föräldrars motivation, hur det motiverande arbetetbeskrivs samt hur motivation förstås utifrån makt och empowerment. Hur motivationsamt den motiverade klienten konstrueras anser vi är en viktig del inom den socialabarn- och ungdomsvården. Sättet metoder och samhället diskuterar begreppetmotivation, samt klienten i relation till detta begrepp, bidrar till förståelsen av hur detsociala arbetet ska utformas och bedrivas. Detta för att förbättra livsomständigheter förindivider och familjer samt ständigt sträva mot förbättring. Vår analys av motivationinom Signs of Safety visar på att diskussionen av motivationsarbetet formas utifrånföreställningar av en ideal klient, vilket medför förväntningar på hur klienten förväntasatt agera och reagera i interaktionen med socialarbetaren. Klienten förutsätts blimotiverad av att inkluderas i Signs of Safetys arbetssätt samt framställs som motiveradoch villig att samarbeta med socialtjänsten. Avslutningsvis anser vi att studien bidrarmed en ökad förståelse över begreppet motivation samt att problematiserasocialarbetarens föreställning av den motiverade klienten.

This thesis documents Phase III of a research program undertaken by the Virginia Transportation Research Council and the Virginia Tech Transportation Institute in cooperation with the 3M Company and the Virginia Department of Transportation for the evaluation of visual performance of retroreflective signs of various color combinations. Phase I was an off-road field experiment conducted to determine the best sign color combination, letter stroke width, and letter size for the emergency sign. Based upon the results of Phase I, three color combinations were chosen for testing (black on coral, black on light blue, and yellow on purple) against a baseline color combination of black on orange.Phase II was conducted using an instrumented vehicle through a construction zone-related detour. Questionnaire data were also obtained. The independent variables of interest were sign color combination, age, and visibility condition. The findings of Phase II indicated that use of a color combination other than the traditional black on orange sign would improve driver performance and safety when used for trailblazing during critical incidents, especially when the incident route overlaps a work zone detour. A serious limitation of Phases I and II is that the use of fluorescent colors was not evaluated. Anecdotal evidence suggests that the use of fluorescent colors on signs improves their conspicuity. The purpose of Phase III was to evaluate fluorescent sign color combinations for incident management trailblazing purposes. This study consisted of an on-road investigation using an instrumented vehicle over a 12.2-mile route in urban and rural areas of Montgomery County, Virginia. The following conclusions were made:*A non-fluorescent yellow on non-fluorescent purple sign is least preferred by both older and younger drivers when compared to the other sign color combinations employed in this study.*Both younger and older drivers have a preference for a black on fluorescent yellow-green sign.* Fewer late braking maneuvers and fewer turn errors were recorded during daytime conditions than during nighttime conditions. *Older drivers tended to register more late braking maneuvers than did younger drivers. / Master of Science