Thesis (MScEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Capacity waste happens when right-turn vehicles have right-of-way during a separate right-turn phase and lanes (e.g., through lanes) of the same approach of the intersection cannot discharge vehicles during that green phase. Right-turn traffic consumes the capacity which otherwise could be provided to through traffic movements at an at-grade signalized intersection. Therefore, it is widely considered that it would lower intersection capacity and increase total delay (Lin, Machemehl, Lee & Herman, 1984). The pre-signal strategy proposed in this research is specifically designed to improve this problem. The following aspects of this strategy were studied in this research, - Capacity benefits of this strategy, - Relationships between the capacity and the length of sorting area (the area between the two signals), - Signal timing of both main signal and pre-signal, - Clearance time of the sorting area, - Main signal phasing options - Signal coordination between the main signal and the pre-signal, - Utilization of the sorting area, and - Pre-signal strategy performance in a simulated environment. The results of this study showed that right-turn movement benefits significantly from this pre-signal strategy. For example, right-turn capacity can be doubled if a presignal is installed on one through lane of an approach with one right-turn lane. It was also found, the maximum approach capacity benefit is not affected significantly by the length of the sorting area for a given green period. The optimal green time and the available pre-signal green time for right-turn movement were also derived in this research. Different main signal phasing options were studied and compared. Phasing options which fit the proposed pre-signal strategy were found. Recommended values for right-turn green time of both signals were given based on different lengths of sorting area. The case study, which compared the performance of some critical movements at the intersection with and without the proposed pre-signal system, confirms the results concluded in this study. A potential problem with this strategy when applied at a real intersection is that it may confuse drivers. Drivers need to be educated and will need time to get familiar with this signal control method. / AFRIKAANSE OPSOMMING: Beskermde regsdraaifases vir verkeer by gelykvlak seinbeheerde kruisings gebruik die kapasiteit wat benut kon word deur deurbewegings. Dit verlaag interseksie kapasiteit en totale oponthoud verhoog. Die voorseinstrategie wat in die navorsing studie voorgestel word is spesifiek ontwikkel om die probleem op te los of te verminder. Die volgende aspekte van die strategie is ondersoek in die navorsingsstudie: - Kapasiteitsvoordele van die strategie. - Die verhouding tussen die kapasiteit en die lengte van die sorteringsarea (die area tussen die twee seine). - Seintydstoedeling van beide die hoofseinfase en die voorseinfase. - Ontruimingstyd van die stoorarea. - Hoofseinfaseopsies. - Seinkoordenasie tussen die hoofsein en die voorsein. - Benutting van die sorterings area, en - Voorseinstrategieprestasie in ‘n gesimuleerde omgewing. Die resultate bewys dat die regsdraaibeweging grootliks bevoordeel word nadat die voorseinstrategie ingestel is. Byvoorbeeld, regsdraaikapasiteit kan verdubbel word as ‘n voorseinfase ingestel word op een van die deurlane tesame met ‘n enkele regsdraailaan. Daar is ook gevind dat die kapasiteit nie grootliks beinvloed word deur die lengte van die stoorgebied nie. Die optimale groentyd en die beskikbare voorsein groen tyd vir die regsdraaibeweging is ook afgelei in die navorsing. Verskillende hoofseinfaseopsies is bestudeer en vergelyk. Faseringsopsies vir die voorgestelde voorseinstrategie is gevind. Voorgestelde waardes vir regsdraaigroentyd van voorseine en hoofseine is bereken om kapasiteit te verbeter, gebasseer op verskillende lengtes van die stoorarea. Die gevallestudie wat die prestasie op ‘n aanloop met en sonder die voogestelde voorseinstrategie vergelyk, bewys resultate wat ooreenstem met die bevindinge in die studie. Die verwagte probleem met die voorseinstrategie, wanneer dit ingestel word by ‘n werklike interseksie, is verwarring van die bestuurders. Bestuurders sal opgevoed moet word en sal tyd nodig hê om gewoond te raak aan die voorseinmetode.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

M.Ing. (Transportation) / Consecutive green phases at signalized intersections are separated by an amber and sometimes all-red period to allow a safe changeover from flow in one direction to another. Al though this signal change interval consists of only a few seconds, existing practice in setting this signal change interval varies considerably. Research on this subj ect has focused on understanding how individual drivers react when they are confronted by a change signal. Identifying the factors that describe the need for different change intervals can most easily be determined by measuring the aggregated behaviour of motorists under conditions where these factors vary. Evidence suggests that the South African driver overseas counterpart regarding his attitude towards interval differs from his the signal change Field observations of drivers' aggregated behaviour when confronted by a change interval were made at 17 approaches to 9 different intersections. The linear relationship between the signal change interval and various factors which apparently have an influence on the need for such a period were determined. The regression models were also structured to allow evaluation of existing models such as the well-known ITE-formula. The results were evaluated statistically. It was not possible to calibrate the ITE-formula for South African conditions. The approach adopted here conforms to tiling designs that use a constant (for a specific approach) amber interval. This constant is probably a summation of the influence of all the factors which influence the need for a signal change interval. The use of the clearance time for a crossing, as the all-red period, is also ascertained.

Neste trabalho são feitas comparações entre os principais sinais horizontais de trânsito (Parada Obrigatória, Faixa de Pedestre e Lombada) padronizados pelo Código de Trânsito Brasileiro (CTB), com modelos alternativos que sofreram variações na forma e/ou cor, alguns deles já usados em algumas cidades brasileiras, com o objetivo de identificar se essas alterações melhoram ou não a percepção do sinal (impacto visual). Para isso são utilizados dois métodos da Psicofísica. Numa primeira etapa a análise é feita utilizando o Método de Comparação aos Pares, para um grupo de quatro estímulos para cada sinal estudado. Em seguida, aplicando o Método de Estimativa das Categorias, foi avaliado o impacto visual do sinal horizontal de Parada Obrigatória quanto à presença ou ausência de orla externa. Por fim, também pelo Método de Comparação aos Pares, foi avaliado o impacto visual causado pelo uso conjugado de sinais horizontais em cruzamentos não semaforizados. Foram estudadas as combinações entre os sinais de parada obrigatória, faixa de pedestres e faixa de retenção. Os resultados obtidos permitem inferir as seguintes conclusões: as alterações na forma e cor propostas para os sinais de parada obrigatória e faixa de pedestres causam maior impacto visual quando comparadas ao modelo padronizado pelo CTB mas, no caso das lombadas, a sinalização padrão mostrou-se ser mais perceptível; quanto a presença ou não da orla externa no sinal de parada obrigatória, esta demonstrou ser positiva; o uso conjugado dos sinais de parada obrigatória, faixa de pedestres e faixa de retenção é a combinação que mais desperta a atenção dos usuários. / This work compares the main horizontal traffic signs (Obligatory Stop, Zebra Crossing and Bump Mark) standardized by the Brazilian Traffic Code (CTB), with alternative models that suffered variations in the form and/or color, some of them already used in some Brazilians cities, with the objective of identifying those alterations get inpruve better or not the perception ofe the sign (visual impact). Two Psychophysics Methods are used in this comparisons. In a first stage the analysis is made using the Comparision in Pair Method, for a group of four stimulus for each studied sign. Afterwards, applying the Categories Estimative Method, the visual impact of Stop sign was evaluated considering the presence or absence of the border. Finally, also using the Comparison in pairs Method, the visual impact caused by the conjugated use of horizontal signs in intersections without traffic lights was evaluated. The combinations among the signs of Stop, Zebra Crossing and Retention Strip were studied. The obtained results allow to infer the following conclusions: the alterations in the form and color proposed for Stop and Zebra Crossing signs cause higher visual impact when compared to the standardized models by CTB, but in the case of the bumps marks, the standard sign has shown to be more perceptible; with the presence or not of the external border in the Stop sign, this was demonstrated to be positive; The conjugated use of the Stop, Zebra Crossing and Retention Strip signs is the combination that more attracts the users attention.

Neste trabalho são feitas comparações entre os principais sinais horizontais de trânsito (Parada Obrigatória, Faixa de Pedestre e Lombada) padronizados pelo Código de Trânsito Brasileiro (CTB), com modelos alternativos que sofreram variações na forma e/ou cor, alguns deles já usados em algumas cidades brasileiras, com o objetivo de identificar se essas alterações melhoram ou não a percepção do sinal (impacto visual). Para isso são utilizados dois métodos da Psicofísica. Numa primeira etapa a análise é feita utilizando o Método de Comparação aos Pares, para um grupo de quatro estímulos para cada sinal estudado. Em seguida, aplicando o Método de Estimativa das Categorias, foi avaliado o impacto visual do sinal horizontal de Parada Obrigatória quanto à presença ou ausência de orla externa. Por fim, também pelo Método de Comparação aos Pares, foi avaliado o impacto visual causado pelo uso conjugado de sinais horizontais em cruzamentos não semaforizados. Foram estudadas as combinações entre os sinais de parada obrigatória, faixa de pedestres e faixa de retenção. Os resultados obtidos permitem inferir as seguintes conclusões: as alterações na forma e cor propostas para os sinais de parada obrigatória e faixa de pedestres causam maior impacto visual quando comparadas ao modelo padronizado pelo CTB mas, no caso das lombadas, a sinalização padrão mostrou-se ser mais perceptível; quanto a presença ou não da orla externa no sinal de parada obrigatória, esta demonstrou ser positiva; o uso conjugado dos sinais de parada obrigatória, faixa de pedestres e faixa de retenção é a combinação que mais desperta a atenção dos usuários. / This work compares the main horizontal traffic signs (Obligatory Stop, Zebra Crossing and Bump Mark) standardized by the Brazilian Traffic Code (CTB), with alternative models that suffered variations in the form and/or color, some of them already used in some Brazilians cities, with the objective of identifying those alterations get inpruve better or not the perception ofe the sign (visual impact). Two Psychophysics Methods are used in this comparisons. In a first stage the analysis is made using the Comparision in Pair Method, for a group of four stimulus for each studied sign. Afterwards, applying the Categories Estimative Method, the visual impact of Stop sign was evaluated considering the presence or absence of the border. Finally, also using the Comparison in pairs Method, the visual impact caused by the conjugated use of horizontal signs in intersections without traffic lights was evaluated. The combinations among the signs of Stop, Zebra Crossing and Retention Strip were studied. The obtained results allow to infer the following conclusions: the alterations in the form and color proposed for Stop and Zebra Crossing signs cause higher visual impact when compared to the standardized models by CTB, but in the case of the bumps marks, the standard sign has shown to be more perceptible; with the presence or not of the external border in the Stop sign, this was demonstrated to be positive; The conjugated use of the Stop, Zebra Crossing and Retention Strip signs is the combination that more attracts the users attention.

When a malfunction occurs in a traffic signal controller cabinet, the signal is automatically placed into malfunction flash mode as a safety precaution. During this event, drivers are presented with one of two possible scenarios: flashing yellow on the major street and flashing red on the minor street, or flashing red on all the approaches. Volumes and percentages of car stopping were collected at fifty-one study intersections in the Atlanta regions. By means of the VISSIM microsimulation software a sample of intersections was simulated under the two malfunction scenarios and the signalized one. Based on output data such as delay and queue, the performances of each simulated intersection is compared and recommendations on which mode of flash must be used in case of malfunction are provided.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 128-130).

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 224-240). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Helsinki University of Technology, 2001. / Includes bibliographical references (p. 49-55). Also available on the World Wide Web.

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Jim P. Zheng, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed June 18, 2004). Includes bibliographical references.