• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 6
  • 5
  • 4
  • Tagged with
  • 20
  • 6
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 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.
11

A System for Travel Time Estimation on Urban Freeways

Dhulipala, Sudheer 05 June 2002 (has links)
Travel time information is important for Advanced Traveler Information Systems (ATIS) applications. People traveling on urban freeways are interested in knowing how long it will take them to reach their destinations, particularly under congested conditions. Though many advances have been made in the field of traffic engineering and ITS applications, there is a lack of practical travel time estimation procedures for ATIS applications. Automatic Vehicle Identification (AVI) and Geographic Information System (GPS) technologies can be used to directly estimate travel times, but they are not yet economically viable and not widely deployed in urban areas. Hence, data from loop detectors or other point estimators of traffic flow variables are predominantly used for travel time estimation. Most point detectors can provide this data efficiently. Some attempts have been made in the past to estimate travel times from point estimates of traffic variables, but they are not comprehensive and are valid for only particular cases of freeway conditions. Moreover, most of these methods are statistical and thus limited to the type of situations for which they were developed and are not of much general use. The purpose of current research is to develop a comprehensive system for travel time estimation on urban freeways for ATIS applications. The system is based on point estimates of traffic variables obtained from detectors. The output required from the detectors is flow and occupancy aggregated for a short time interval of 5 minutes. The system for travel time estimation is based on the traffic flow theory rather than statistical methods. The travel times calculated using this system are compared with the results of FHWA simulation package TSIS 5.0 and the estimation system is found to give reasonable and comparable results when compared with TSIS results. / Master of Science
12

Lenses of Connectivity: Adapting the Impact of Urban Highways on American Cities

Hayes, Andrew Michael 30 September 2016 (has links)
Once thriving neighborhoods in mid-sized American cities have been decimated, scarred and disrupted by the serpentine free form highways that have touched them. This product of technological innovation from the 1950s and 60s has had a profound and disturbing affect upon American cities. The collective history, cultural rituals and organic urban fabric of life has been almost completely extinguished in these cities by the false opportunity and instant gratification that comes with so-called 'technological progress.' This, yes this, epitomizes the urban core of a majority of cities across the United States early in the early 21st century. What is to be the future legacy of these American cities upon the life of their residents? It quickly became apparent that to develop a deep understanding of this urban challenge, it was going to be necessary to carefully examine cites that have been acutely affected by urban highways. The neighborhoods at the core of these damaged American cities trudge on'.. Why? Because they have no other option'. The question currently at hand is how can these damaged neighborhoods adjacent to urban highways, and their associated cities, be regenerated? The research phase of this thesis exposed four critical elements of a thriving and organic urban neighborhood; connectivity, realness, livability and performativity. I was encouraged to focus upon and explore this notion of connectivity by my thesis committee, as it represents the element offering the most agency for the design professions. Through interrogating the [dis]connectivity of four specific neighborhoods in Baltimore, Buffalo, Richmond and St Petersburg certain operational systems began to evolve. These systems center around three critical lenses of focus; the economic, social and physical operations that occur within and adjacent to an urban neighborhood. Due to its acute condition, the Gilpin neighborhood of Richmond, Virgina was chosen as a case study to employ the lenses of connectivity through close examination and intervention. / Master of Science / Once thriving neighborhoods in mid-sized American cities have been decimated, scarred and disrupted by the serpentine free form highways that have touched them. This product of technological innovation from the 1950s and 60s has had a profound and disturbing affect upon American cities. The collective history, cultural rituals and organic urban fabric of life has been almost completely extinguished in many of these cities by the false opportunity and instant gratification that comes with so-called ‘technological progress.’ This, yes this, epitomizes the urban core of a majority of cities across the United States early in the early 21st century. <b>What is to be the future legacy of these American cities upon the life of their residents?</b> The neighborhoods at the core of these damaged American cities trudge on… Why? Because they have no other option... <b>The question currently at hand is how can these neighborhoods adjacent to urban highways, and their associated cities, be regenerated?</b> Through interrogating the [dis]connectivity of four specific neighborhoods in Baltimore, Buffalo, Richmond, and St Petersburg certain operational systems began to become apparent. These systems center around three critical lenses of focus; the economic, social, and physical operations that occur within and adjacent to an urban neighborhood. Due to its acute condition, the Gilpin neighborhood of Richmond, Virginia was chosen as a case study to employ the lenses of connectivity through closer examination and intervention.
13

A Baseline Study of Biofuel Feedstock Growth on Non-Traditional Agronomic Land in Utah

Hanks, Dallas A. 01 May 2012 (has links)
The goal of the Non-Traditional Agronomic Land (NTAL) Project is to develop sustainable, agronomic, crop growth methods that will allow biofuel feedstock production to occur on marginal or non-traditional plots of land, e.g., roadways, railroads, airports, and military installations. Recent economic feasibility models by Utah State University (USU) indicate these lands could, in theory, produce one billion gallons of economically viable new feedstock annually. Specifically, USU models show that if 60 % (600 pounds/acre) of dry land oilseed can be produced, maintenance costs of these NTALs can be recovered, as well as production of approximately 25 gallons/acre of renewable biodiesel. This feedstock yield would increase U.S. biodiesel production between 100- 200 %, and save federal and state agencies substantial financial resources. Preliminary impact considerations that have been taken into account for production on non-traditional land include: safety, structural integrity, economics, wildlife impacts, ecology/environmental impacts, water quality and grower concerns, soil quality, water use, generation/reduction of hazardous/toxic substances, air emissions, wastewater discharges, and reductions in use of pesticides and fertilizer. Canola and Safflower plots were established in 2007 and 2008 along roadsides in four different regions of the Utah I-15 corridor. Harsh climatic conditions with above average temperatures and below average precipitation existed in both years. Less than 50 % average yields for safflower and 25 % average yields for canola under normal climatic conditions were produced. Roadside plots all yielded under 200 pounds/acre of seed for both crops. In 2008, seeds were placed 2 inches deep during planting to position them closer to moisture, and no measureable yield was observed for any crops in control plots planted on traditional farmland and less than 10 pounds/acre in roadside plots. We found that it was not economical to grow oilseed crops for biodiesel production along Utah roadsides under the climatic conditions experienced during 2007- 2008 while using a Tye Pasture Pleaser No-Till Drill. (98 Pages)
14

Capacidade e relação fluxo-velocidade em autoestradas e rodovias de pista dupla paulistas / Capacity and speed-flow relationship for freeways and multilane highways in the state of São Paulo

Andrade, Gustavo Riente de 07 May 2012 (has links)
Neste trabalho, calibra-se um modelo que descreva a relação fluxo-velocidade em autoestradas e rodovias de pista dupla, considerando as recomendações tecidas pelos autores envolvidos na elaboração do modelo do Highway Capacity Manual - HCM 2010. Para tanto, foi utilizada uma amostra de 788.122 observações, coletadas por 25 estações em quatro rodovias paulistas: SP-348, SP-021, SP-280 e SP 270. A análise dos dados mostrou que, conforme preconizado pelo HCM 2010, existe um intervalo de fluxos no qual a velocidade se mantém constante, o que corresponde à velocidade de fluxo livre. Em seguida, verificou-se que a classificação do HCM 2010, entre autoestradas e rodovias de pista dupla, não se mostra adequada para a amostra estudada, tendo sido indicada a divisão entre rodovias urbanas e rurais. Para esses grupos, foram propostos valores representativos para a capacidade e calibrada a relação fluxo-velocidade. A comparação entre os dois conjuntos de curvas produzidos mostrou que a velocidade média da corrente de tráfego nas rodovias urbanas apresenta uma queda mais precoce e acentuada do que a observada em rodovias rurais. Além disso, os valores estimados para a capacidade C e para a velocidade na capacidade CS para rodovias urbanas são inferiores aos estimados para rodovias rurais. Em contraste com o modelo do HCM 2010, a principal diferença reside em valores significativamente inferiores para BP, o fluxo a partir do qual se nota um declínio da velocidade em função do aumento da densidade da corrente de tráfego. Outro ponto de destaque é que, embora os valores da capacidade sejam parecidos entre o modelo do HCM 2010 e o calibrado, a velocidade na capacidade CS é superior nas rodovias paulistas. / This work presents the calibration of a model describing the speed-flow relationship on freeways and multilane highways in the state of São Paulo, Brazil. The calibrated model follows the recommendations made by the authors involved in the development of the model used by the Highway Capacity Manual HCM 2010. The calibration used a sample of 788,122 observations, collected by 25 stations on four highways at São Paulo state: SP-348, SP-021, SP-280 and 270 SP. The analysis of the data showed that, as advocated by the HCM 2010, there is range of flows in which the average speed of the passenger cars remains constant and equal to the free flow speed. It was also found that the classification scheme used by HCM 2010, comprising freeways and multilane highways, is not adequate for highways in the state of São Paulo. A new classification scheme, which divides highways into urban or rural sections, is proposed. For these classes, representative values for the capacity were found, and the speed-flow relation was calibrated. The comparison between the two sets of curves produced showed that the average speed of the traffic stream on urban highways has an earlier and steeper drop than the observed on rural highways. In addition, the estimated values for the capacity C and for the speed at capacity CS for urban highways are lower compared to the estimated for rural highways. Compared to the model used by the HCM 2010, the main difference lies in the significantly lower values for BP, the traffic flow from which the average speed declines as the density of the traffic stream increases. Another important indication is that, although the capacity values are similar between the model used by the HCM 2010 and the calibrated model, the speed at capacity CS is higher at São Paulo state highways.
15

Capacidade e relação fluxo-velocidade em autoestradas e rodovias de pista dupla paulistas / Capacity and speed-flow relationship for freeways and multilane highways in the state of São Paulo

Gustavo Riente de Andrade 07 May 2012 (has links)
Neste trabalho, calibra-se um modelo que descreva a relação fluxo-velocidade em autoestradas e rodovias de pista dupla, considerando as recomendações tecidas pelos autores envolvidos na elaboração do modelo do Highway Capacity Manual - HCM 2010. Para tanto, foi utilizada uma amostra de 788.122 observações, coletadas por 25 estações em quatro rodovias paulistas: SP-348, SP-021, SP-280 e SP 270. A análise dos dados mostrou que, conforme preconizado pelo HCM 2010, existe um intervalo de fluxos no qual a velocidade se mantém constante, o que corresponde à velocidade de fluxo livre. Em seguida, verificou-se que a classificação do HCM 2010, entre autoestradas e rodovias de pista dupla, não se mostra adequada para a amostra estudada, tendo sido indicada a divisão entre rodovias urbanas e rurais. Para esses grupos, foram propostos valores representativos para a capacidade e calibrada a relação fluxo-velocidade. A comparação entre os dois conjuntos de curvas produzidos mostrou que a velocidade média da corrente de tráfego nas rodovias urbanas apresenta uma queda mais precoce e acentuada do que a observada em rodovias rurais. Além disso, os valores estimados para a capacidade C e para a velocidade na capacidade CS para rodovias urbanas são inferiores aos estimados para rodovias rurais. Em contraste com o modelo do HCM 2010, a principal diferença reside em valores significativamente inferiores para BP, o fluxo a partir do qual se nota um declínio da velocidade em função do aumento da densidade da corrente de tráfego. Outro ponto de destaque é que, embora os valores da capacidade sejam parecidos entre o modelo do HCM 2010 e o calibrado, a velocidade na capacidade CS é superior nas rodovias paulistas. / This work presents the calibration of a model describing the speed-flow relationship on freeways and multilane highways in the state of São Paulo, Brazil. The calibrated model follows the recommendations made by the authors involved in the development of the model used by the Highway Capacity Manual HCM 2010. The calibration used a sample of 788,122 observations, collected by 25 stations on four highways at São Paulo state: SP-348, SP-021, SP-280 and 270 SP. The analysis of the data showed that, as advocated by the HCM 2010, there is range of flows in which the average speed of the passenger cars remains constant and equal to the free flow speed. It was also found that the classification scheme used by HCM 2010, comprising freeways and multilane highways, is not adequate for highways in the state of São Paulo. A new classification scheme, which divides highways into urban or rural sections, is proposed. For these classes, representative values for the capacity were found, and the speed-flow relation was calibrated. The comparison between the two sets of curves produced showed that the average speed of the traffic stream on urban highways has an earlier and steeper drop than the observed on rural highways. In addition, the estimated values for the capacity C and for the speed at capacity CS for urban highways are lower compared to the estimated for rural highways. Compared to the model used by the HCM 2010, the main difference lies in the significantly lower values for BP, the traffic flow from which the average speed declines as the density of the traffic stream increases. Another important indication is that, although the capacity values are similar between the model used by the HCM 2010 and the calibrated model, the speed at capacity CS is higher at São Paulo state highways.
16

Empirical Estimation of a Macroscopic Fundamental Diagram (MFD) for the City of Cape Town Freeway Network

Rammutla, John Koketso 26 February 2021 (has links)
The City of Cape Town is the most congested city in South Africa, with Johannesburg coming in second. Capetonians are spending 75% more time in traffic because of the congestion during peak hours, thus reducing time spent on leisure and other activities. Due to population growth, increasing car ownership and declining capacity of rail infrastructure, Cape Town's road infrastructure will continue to be under severe pressure if the status quo is maintained. Research shows that congestion levels in urban areas are key factors in determining the effectiveness and productivity of the transport system. Traffic congestion poses a threat to the economy and the environment. Increasing corridors' capacity by increasing the number of lanes does not necessarily solve the problem. Effective urban traffic management and efficient utilization of existing infrastructure are critical in creating sustainable solutions to congestion problems. To achieve this, it is important that appropriate urban-scale models and monitoring strategies are put in place. Effective traffic management and monitoring strategies require accurate characterization of the traffic state of an urban-scale network. Several approaches, including kinetic wave theory and cell transmission models or macroscopic traffic simulation models, have been proposed and developed to describe the traffic state of an urban-scale network. However, these approaches are limited and require significant amounts of computational time and effort. The application of macroscopic fundamental diagram (herein referred to as MFD) to characterize the state of an urban-scale network has thus far proven to be more effective than other approaches. MFD represents the state of urban traffic by defining the traffic throughput of an area at given traffic densities. It describes the characteristics and dynamics of urban-scale traffic conditions, allowing for improved and sustainable urban scale traffic management and monitoring strategies. Against this backdrop, the existence of MFD for the City of Cape Town (CoCT) urbanscale network is yet to be established and the implications yet to be understood, as in other parts of the world. The main aim of this research was, therefore, to empirically estimate the macroscopic fundamental diagram for the CoCT's freeway network and analyse its observed features. To achieve this, observed data of 5 minutes periods for the month of May 2019 was used to estimate the MFD. The results confirmed that when the chaotic scatter-plots of flow and density from individual fixed loop detectors were aggregated the scatter nearly disappeared and points grouped neatly to form a clearly defined free-flow state, critical state and the formation of hysteresis loops past the critical density corresponding with the network observed maximum flow. Further analysis of the MFDs showed that a single hysteresis loop always forms past the critical density during the evening peak in a weekday MFD. However, it was inconclusive during the morning peak period in weekday MFDs. Lastly, an explicit hysteresis loop seldom appears in a Saturday MFD when the peak of traffic demand is lower than on weekdays. In order to understand the dynamics of the congestion spread, the freeway network was partitioned into penetrating highways network and the ring highway network. The results showed that the maximum flows observed for the two sub-networks were significantly different (943 veh/hr/lane for the penetrating highways network and 1539 veh/hr/lane for the ring highway network). The penetrating highways network's MFD indicated the presence of congestion in the network whereas the ring highway network indicated only the free-flow state (no indication of congestion) during peak periods. The congestion seen on the penetrating highways network was found not to be sufficiently spread on those highways. On the 24th May, congestion on the penetrating highway network was observed during both the morning and evening peak periods, whereas on the 31st May congestion was observed mainly during the evening peak period, with hysteresis-like shape. These observations confirmed that congestion during peak periods is not homogenously spread across the entire network, certain areas are more congested than others, hence the observed formation of hysteresis loops and slight scatters. Lastly, the hysteresis loops observed in the penetrating highways network's MFD was further characterized in terms of their shape and size. First, the results showed that the slight scatter and hysteresis patterns observed in penetrating highways network MFD's vary in size and shape across different days. The shapes of the hysteresis loops observed during both the morning and evening peak periods, were type H2 hysteresis loops, signifying a stable recovery of the network with the average network flow remaining unchanged as average network density decreases during the recovery. Characterization of the size of the observed hysteresis loops showed that the drop of the hysteresis (an indicator of network level of instability during recovery phase) was smaller, signifying a more stable network traffic and homogenous distribution of congestion during the recovery phase.
17

The Safety Impact of Raising Speed Limit on Rural Freeways In Ohio

Olufowobi, Oluwaseun Temitope 01 September 2020 (has links)
No description available.
18

As interven??es urbanas em Buenos Aires no ?ltimo governo militar (1976-1983): a erradica??o das Villas e o Plan de Autopistas

Vega, Jimena Alejandra 18 February 2013 (has links)
Made available in DSpace on 2016-04-04T18:22:07Z (GMT). No. of bitstreams: 1 Jimena Alejandra Vega.pdf: 11387367 bytes, checksum: e8b97232a2e5431bad6f21327531f495 (MD5) Previous issue date: 2013-02-18 / This work aims to analyze the successive urban policies adopted in Buenos Aires and, in particular, urban planning and interventions in urban space during the last Argentine dictatorship period. It seeks to contextualize these interventions in the urban thinking timeline of this city along the twentieth century, in order to understand the historical factors behind these urban policies and the developments that led to the structural changes that today characterize the contemporary city. By analyzing the successive urban policies adopted in Buenos Aires and, in particular, planning and interventions in urban space of the last Argentine dictator ship period, the study focuses on the one hand, the housing policies in the Federal Capital, understood as a vector backbone for modeling Buenos Aires urban space, and secondly, the road system designed for particular vehicular high-speed transport, understood within a plan of urban modernization. The research aims to contribute to a better understanding of the actions of the state represented by the last military government in the field of socio-spatial policies, in order to understand how far the urban intervention strategies contributed to a greater fragmentation of the sociopolitical-spacial tissue, and to the reproduction processes of the capitalist dynamics in the city of Buenos Aires, whose features can still be seen today in the production of its urban space. / Esse trabalho objetiva estudar as interven??es urbanas em Buenos Aires e, em especial, as estrat?gias e pr?ticas espaciais do ?ltimo per?odo ditatorial argentino. Procura-se contextualizar tais interven??es a partir da an?lise do pensamento urbano ao longo do s?culo XX sobre a capital portenha, com o intuito de entender que fatores determinaram a ado??o dessas pol?ticas urbanas, seus desdobramentos e as transforma??es estruturais que at? hoje marcam o tecido urbano da cidade. Ao analisar as sucessivas pol?ticas urbanas adotadas em Buenos Aires e, em especial, o planejamento e as interven??es no espa?o urbano do ?ltimo per?odo ditatorial argentino, o estudo privilegia, por um lado, as pol?ticas habitacionais na Capital Federal, entendidas como vetor estruturante na modelagem do espa?o urbano portenho, e por outro, o sistema vi?rio projetado para o transporte veicular particular de alta velocidade, compreendido dentro de um plano de moderniza??o urbana. A pesquisa pretende contribuir para uma maior compreens?o das a??es do Estado autorit?rio no campo das pol?ticas urbanas, buscando entender at? que ponto as interven??es realizadas, ou mesmo apenas projetadas, contribu?ram para a amplia??o da fragmenta??o do tecido sociopol?tico-espacial, e como fator favor?vel aos processos de reprodu??o da din?mica capitalista na cidade de Buenos Aires.
19

Calibração da relação fluxo-velocidade para autoestradas e rodovias de pista dupla / Calibration of speed-flow relationship for freeways and multilane highways

Oliveira, Gabriel Jurado Martins de 20 July 2018 (has links)
Esta pesquisa apresenta um método de calibração da relação fluxo-velocidade do Highway Capacity Manual, HCM, para autoestradas e rodovias de pista dupla, a partir de recomendações tecidas pelos autores envolvidos na elaboração do manual. Para tanto, foi utilizado uma amostra com mais de 1.700.000 observações, coletadas por 34 sensores de tráfego, localizados em quatros rodovias do Estado de São Paulo: SP-280, SP-348, SP-270 e SP-021. O tratamento do banco de dados foi realizado por meio da filtragem dos dados originais através da aplicação de três critérios, que têm como finalidade remover observações consideradas inadequadas para a calibração do modelo. Os critérios baseiam-se em obter uma corrente de tráfego formada somente por veículos leves, com condições de operação normal e com observações referentes apenas ao regime de fluxo livre. A separação entre os regimes de fluxo livre e congestionado foi realizada por meio da densidade na capacidade. Para tanto, foi proposto um método de estimação da capacidade por meio da análise da variação da velocidade média da corrente em função do fluxo de tráfego. O pressuposto do método parte do conceito de que o colapso da corrente de tráfego é um fenômeno estocástico, caracterizado pela queda abrupta da velocidade média em função do aumento do fluxo de tráfego. O momento em que ocorre mudança abrupta de velocidade é associado ao colapso da corrente de tráfego e consequentemente à capacidade da via. Após a estimação da capacidade, a velocidade na capacidade foi determinada como a média das velocidades associadas ao fluxo na capacidade, enquanto que a densidade na capacidade foi obtida por meio da relação fundamental de tráfego. O método foi aplicado em um conjunto de 18 trechos de rodovias que atingem a capacidade e os resultados foram considerados satisfatórios após a comparação com valores encontrados na literatura. A calibração da relação fluxo-velocidade foi realizada individualmente para cada trecho de rodovia utilizado no estudo. A análise dos resultados mostra que as rodovias rurais apresentam em média valores maiores para velocidade de fluxo livre, capacidade, coeficiente de calibração, velocidade na capacidade e ponto de transição em relação as rodovias urbanas. Alem disso, o ponto de transição, que consiste em um patamar de velocidade de fluxo livre constante, apresenta valores significativamente menores em relação a literatura. / The following research aims to outline a calibration method of the speed-flow relationship presented in the Highway Capacity Manual (HCM). The method is applied on freeways and multilane highways, leveraging the guidelines made by the authors that developed the manual. In order to support the calibration, a sample with more than 1.700.000 observations was used, collected by 34 traffic sensors on four highways at São Paulo state (SP-280, SP-348, SP270, and SP-021). Furthermore, the data treatment and cleaning process aimed to remove observations considered inappropriate from a model calibration perspective by filtering the original data through three main criteria: traffic flow only composed by passenger car, traffic under normal operations condition, and only containing observations which free flow regime applies. The third filtering criteria was applied by splitting free flow and congested regime through the threshold of density at capacity. To this extent, a capacity estimation method was proposed, aiming to analyse the average speed variation in function of the traffic flow. The assumption of the method relies in the concept that the traffic flow breakdown is a stochastic process, characterized by the abrupt drop in the average speed as function of the traffic flow increase. The moment that abrupt drop occurs is related to traffic breakdown and, consequently, to the capacity freeway capacity. Once the capacity was estimated, the speed at capacity was defined as the average of the speed associated with the flow at capacity while the density at capacity was estimated through the fundamental relationship of the traffic flow. The method was applied in 18 delimited highway traffic perimeter that reached their corresponding capacity and the results were considered satisfactory after comparing against values found in the literature. Furthermore, the speed-flow relationships calibration was performed for each of them individually. The results show that rural highways have in average higher free flow speed, capacity, calibration coefficient, speed at capacity and breakpoint than urban highways. Moreover, the breakpoint, which consists a constant free flow speed level, presented significant lower values in comparison to the literature.
20

Calibração da relação fluxo-velocidade para autoestradas e rodovias de pista dupla / Calibration of speed-flow relationship for freeways and multilane highways

Gabriel Jurado Martins de Oliveira 20 July 2018 (has links)
Esta pesquisa apresenta um método de calibração da relação fluxo-velocidade do Highway Capacity Manual, HCM, para autoestradas e rodovias de pista dupla, a partir de recomendações tecidas pelos autores envolvidos na elaboração do manual. Para tanto, foi utilizado uma amostra com mais de 1.700.000 observações, coletadas por 34 sensores de tráfego, localizados em quatros rodovias do Estado de São Paulo: SP-280, SP-348, SP-270 e SP-021. O tratamento do banco de dados foi realizado por meio da filtragem dos dados originais através da aplicação de três critérios, que têm como finalidade remover observações consideradas inadequadas para a calibração do modelo. Os critérios baseiam-se em obter uma corrente de tráfego formada somente por veículos leves, com condições de operação normal e com observações referentes apenas ao regime de fluxo livre. A separação entre os regimes de fluxo livre e congestionado foi realizada por meio da densidade na capacidade. Para tanto, foi proposto um método de estimação da capacidade por meio da análise da variação da velocidade média da corrente em função do fluxo de tráfego. O pressuposto do método parte do conceito de que o colapso da corrente de tráfego é um fenômeno estocástico, caracterizado pela queda abrupta da velocidade média em função do aumento do fluxo de tráfego. O momento em que ocorre mudança abrupta de velocidade é associado ao colapso da corrente de tráfego e consequentemente à capacidade da via. Após a estimação da capacidade, a velocidade na capacidade foi determinada como a média das velocidades associadas ao fluxo na capacidade, enquanto que a densidade na capacidade foi obtida por meio da relação fundamental de tráfego. O método foi aplicado em um conjunto de 18 trechos de rodovias que atingem a capacidade e os resultados foram considerados satisfatórios após a comparação com valores encontrados na literatura. A calibração da relação fluxo-velocidade foi realizada individualmente para cada trecho de rodovia utilizado no estudo. A análise dos resultados mostra que as rodovias rurais apresentam em média valores maiores para velocidade de fluxo livre, capacidade, coeficiente de calibração, velocidade na capacidade e ponto de transição em relação as rodovias urbanas. Alem disso, o ponto de transição, que consiste em um patamar de velocidade de fluxo livre constante, apresenta valores significativamente menores em relação a literatura. / The following research aims to outline a calibration method of the speed-flow relationship presented in the Highway Capacity Manual (HCM). The method is applied on freeways and multilane highways, leveraging the guidelines made by the authors that developed the manual. In order to support the calibration, a sample with more than 1.700.000 observations was used, collected by 34 traffic sensors on four highways at São Paulo state (SP-280, SP-348, SP270, and SP-021). Furthermore, the data treatment and cleaning process aimed to remove observations considered inappropriate from a model calibration perspective by filtering the original data through three main criteria: traffic flow only composed by passenger car, traffic under normal operations condition, and only containing observations which free flow regime applies. The third filtering criteria was applied by splitting free flow and congested regime through the threshold of density at capacity. To this extent, a capacity estimation method was proposed, aiming to analyse the average speed variation in function of the traffic flow. The assumption of the method relies in the concept that the traffic flow breakdown is a stochastic process, characterized by the abrupt drop in the average speed as function of the traffic flow increase. The moment that abrupt drop occurs is related to traffic breakdown and, consequently, to the capacity freeway capacity. Once the capacity was estimated, the speed at capacity was defined as the average of the speed associated with the flow at capacity while the density at capacity was estimated through the fundamental relationship of the traffic flow. The method was applied in 18 delimited highway traffic perimeter that reached their corresponding capacity and the results were considered satisfactory after comparing against values found in the literature. Furthermore, the speed-flow relationships calibration was performed for each of them individually. The results show that rural highways have in average higher free flow speed, capacity, calibration coefficient, speed at capacity and breakpoint than urban highways. Moreover, the breakpoint, which consists a constant free flow speed level, presented significant lower values in comparison to the literature.

Page generated in 0.048 seconds