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In this thesis, seven multi-sensor data fusion based estimation techniques are investigated. All methods are compared in terms of their ability to fuse data from loop detectors and Bluetooth tracked probe vehicles to accurately estimate freeway traffic speed. In the first case study, data generated from a microsimulation model are used to assess how data fusion might perform with present day conditions, having few probe vehicles, and what sort of improvement might result from an increased proportion of vehicles carrying Bluetooth-enabled devices in the future. In the second case study, data collected from the real-world Bluetooth traffic monitoring system are fused with corresponding loop detector data and the results are compared against GPS collected probe vehicle data, demonstrating the feasibility of implementing data fusion for real-time traffic monitoring today. This research constitutes the most comprehensive evaluation of data fusion techniques for traffic speed estimation known to the author.

In this thesis, seven multi-sensor data fusion based estimation techniques are investigated. All methods are compared in terms of their ability to fuse data from loop detectors and Bluetooth tracked probe vehicles to accurately estimate freeway traffic speed. In the first case study, data generated from a microsimulation model are used to assess how data fusion might perform with present day conditions, having few probe vehicles, and what sort of improvement might result from an increased proportion of vehicles carrying Bluetooth-enabled devices in the future. In the second case study, data collected from the real-world Bluetooth traffic monitoring system are fused with corresponding loop detector data and the results are compared against GPS collected probe vehicle data, demonstrating the feasibility of implementing data fusion for real-time traffic monitoring today. This research constitutes the most comprehensive evaluation of data fusion techniques for traffic speed estimation known to the author.

Baigiamajame magistro darbe apžvelgiama avaringumo Lietuvos Respublikos valstybinės reikšmės keliuose situacija. Darbe analizuojama automatizuotos važiavimo greičio kontrolės sistemos diegimo Lietuvos automobilių keliuose patirtis, pateikiama automobilių važiavimo greičio tyrimų Lietuvos keliuose analizė. Baigiamajame darbe nagrinėjami visuomenės nuomonės apie automatizuotos važiavimo greičio kontrolės sistemos poveikį eismo saugumui tyrimo rezultatai bei vandalizmo atvejai prieš stacionarius greičio matuoklius. Darbo pabaigoje pateikiamos išvados ir rekomendacijos. Baigiamojo darbo apimtis – 101 psl. teksto be priedų, 30 lentelių, 63 paveikslai ir 3 priedai. / In this Master Thesis an overview of the Republic of Lithuania accident rate situation on national significant roads are given. An analysis of automatic traffic speed control system implementation experience in Lithuanian roads and car speed research on Lithuanian roads are given in this final paper. Also a part of the work reveals research results of public opinion on automatic speed control system influence to traffic safety and cases of vandalism against fixed speed cameras. Conclusions and recommendations are given at the end of the paper. Master thesis consists of 101 pages pure text without appendixes, 30 tables, 63 pictures ant 3 appendixes.

Operating speed is one of the best performance measures that can tell transportation agencies how well or how poorly the transportation system is functioning. Fluctuating operating speeds often mean there is a design flaw or something about the physical road design that violates drivers' expectations. A primary example of this is a horizontal curve on a highway that had a reduced recommended advisory speed. Traditionally, researchers and transportation agencies measure operating speeds along the approach tangent to a horizontal curve and at the midpoint of the curve. This thesis looks at the significance of alternate measuring locations within the curve. It also analyzes the difference between the 85th percentile maximum speed reduction and the more traditional measure of the reduction in 85th percentile speeds, which is used as an indicator of safety. / Graduation date: 2012

Pavement structural condition plays a critical role in the rate of pavement deterioration, yet most state highway agencies' network-level decision-making processes are primarily based on surface distresses. Despite the limitations of the traditional structural condition measuring devices, some states have experimented with stationary deflection devices for network-level applications. Over the past decade, continuous deflection devices have become capable of measuring the network-level pavement structural condition information. However, since the traffic speed deflection devices use newer technology, there is a need for guidelines on how the state agencies could make use of this information for pavement management decision-making. This dissertation developed processes and enhanced tools to incorporate the pavement structural condition from the TSD into Virginia's network-level pavement management process This first part of the study developed pavement deterioration models for a subset of road networks in Virginia, to show that the pavement structural condition as measured by the TSD has an impact on the rate of deterioration of the surface condition. A structural condition matrix was then developed to augment the treatment selection process currently used by VDOT. Application of the augmented matrix on the tested Interstate network resulted in reducing the percentage of the network requiring CM and increasing the percentage requiring PM and RM. The second part of the study investigated the possibility of using pavement deflection measurements obtained from the TSD for network-level structural evaluation of pavements in Virginia. The study reported that the structural condition obtained with the TSD can replace the structural condition obtained from the FWD that is currently used in the VDOT PMS. The effective structural number (SNeff) calculated from the TSD and FWD had similar distribution, and the calculated consistency between the TSD SNeff and FWD SNeff was higher than the consistency between the SNeff from two repeated sets of FWD measurements. The third part of the study simulated the network level decision-making approaches based on both the structural condition parameter and the surface condition parameter, considering cases with and without the pavement treatment interval. The study reported that network-level decisions based on the pavement surface condition alone can result in significantly different treatment selection, compared to decisions based on the pavement structural condition. The study reported savings of 9% and 11% for cases with and without considering the pavement treatment intervals, using decision-making based on the structural condition. / Doctor of Philosophy / Pavement structural condition plays a critical role in the rate of pavement deterioration, yet most state highway agencies' network-level decision-making processes are primarily based on surface distresses. Despite the limitations of the traditional structural condition measuring devices, some states have experimented with stationary deflection devices for network-level applications. Over the past decade, continuous deflection devices have become capable of measuring the network-level pavement structural condition information. However, since the traffic speed deflection devices use newer technology, there is a need for guidelines on how the state agencies could make use of this information for pavement management decision-making. This dissertation developed processes and enhanced tools to incorporate the pavement structural condition from the TSD into Virginia's network-level pavement management process' This first part of the study developed pavement deterioration models for a subset of road networks in Virginia, to show that the pavement structural condition as measured by the TSD has an impact on the rate of deterioration of the surface condition. A structural condition matrix was then developed to augment the treatment selection process currently used by VDOT. Application of the augmented matrix on the tested Interstate network resulted in reducing the percentage of the network requiring CM and increasing the percentage requiring PM and RM. The second part of the study investigated the possibility of using pavement deflection measurements obtained from the TSD for network-level structural evaluation of pavements in Virginia. The study reported that the structural condition obtained with the TSD can replace the structural condition obtained from the FWD that is currently used in the VDOT PMS. The effective structural number (SNeff) calculated from the TSD and FWD had similar distribution, and the calculated consistency between the TSD SNeff and FWD SNeff was higher than the consistency between the SNeff from two repeated sets of FWD measurements. The third part of the study simulated the network level decision-making approaches based on both the structural condition parameter and the surface condition parameter, considering cases with and without the pavement treatment interval. The study reported that network-level decisions based on the pavement surface condition alone can result in significantly different treatment selection, compared to decisions based on the pavement structural condition. The study reported savings of 9% and 11% for cases with and without considering the pavement treatment intervals, using decision-making based on the structural condition.

This thesis presents (a) results of a field evaluation of the Traffic Speed Deflectometer (TSD) in the United States (b) deflection thresholds to classify the pavement structural condition obtained from the TSD for a small subset of the Pennsylvania secondary road network. The results of the field evaluation included: (1) repeatability of the TSD, (2) ability of the TSD to identify pavement sections with varying structural conditions, and (3) consistency between the structural number (SNeff) calculated from the TSD and SNeff calculated by the Pennsylvania Department of Transportation (PennDOT). The results showed consistent error standard deviation in the TSD measurements and that the TSD was able to identify pavement sections that varied in structural condition. Comparison of the SNeff calculated with TSD measurements, using an empirically developed equation by Rohde, with the SNeff calculated by PennDOT’s Pavement Management System based on construction history showed similar trends, although the TSD-calculated SNeff was higher. In order to develop deflection thresholds, a model that related the pavement surface condition to pavement surface age and structural condition was developed. Structural condition thresholds were then selected so that the pavement surface condition predicted from the model for a 10-year-old pavement surface fell within one of the three condition categories (Good, Fair, and Poor), to identify pavements in good, fair and poor condition. With Overall Pavement Index(OPI) characterizing the surface condition and Deflection Slope Index(DSI) characterizing the structural condition, the DSI threshold that separates structurally good from structurally fair pavements was determined as follows: (1) the OPI threshold that separates pavements with good surface condition from those with fair surface condition was obtained from the Pennsylvania Pavement Management System (PMS) and (2) the DSI thresholds were calculated using the determined OPI value and the model equation. / Master of Science / This thesis presents (a) some of the results of a field evaluation of the Traffic Speed Deflectometer (TSD) in the United States (b) deflection thresholds to classify the pavement structural condition obtained from the TSD for a small subset of the Pennsylvania secondary road network. The results of the field evaluation included: (1) repeatability of the TSD: which is the variation in repeated TSD measurements on the same section of the road, (2) ability of the TSD to identify pavement sections with varying structural conditions, and (3) consistency between the structural number (SNeff) calculated from the TSD and SNeff calculated by the Pennsylvania Department of Transportation (PennDOT). The pavement structural number is an abstract number expressing the structural strength of the pavement. The results showed that the TSD measurements were repeatable and that the TSD was able to identify pavement sections that varied in structural condition. Comparison of the SNeff calculated with TSD measurements, using an empirically developed equation by Rohde, with the SNeff calculated by PennDOT Pavement Management System based on construction history showed similar trends, although the TSD-calculated SNeff was higher. In order to develop deflection thresholds to categorize pavements in different condition: good, fair and poor, a model that related the pavement surface condition to pavement surface age and structural condition was developed. Structural condition thresholds were then selected so that the pavement surface condition predicted from the model for a 10-year-old pavement surface fell within one of the three condition categories (Good, Fair, and Poor), to identify pavements in good, fair and poor condition. With Overall Pavement Index(OPI) characterizing the surface condition and Deflection Slope Index(DSI) characterizing the structural condition, the DSI threshold that separates structurally good from structurally fair pavements was determined as follows: (1) the OPI threshold that separates pavements with good surface condition from those with fair surface condition was obtained from the Pennsylvania Pavement Management System (PMS) and (2) the DSI thresholds were calculated using the determined OPI value and the model equation.

Changing speed limit leads to proportional changes in average speeds which may affect the number of traffic accident occurrences. It is however critical and challenging to evaluate the impact of a speed limit alteration on the number and severity of accidents due primarily to the unavailability of adequate data and the inherent limitations of existing approaches. Although speed is regarded as one of the main contributory factors in traffic accident occurrences, research findings are inconsistent. Independent of the robustness of their statistical approaches, accident frequency models typically use accident grouping concepts based on spatial criteria (e.g. accident counts by link termed as a link-based approach). In the link-based approach, the variability of accidents is explained by highly aggregated average measures of explanatory variables that may be inappropriate, especially for time-varying variables such as speed and volume. This thesis re-examines accident-speed relationships by developing a new accident data aggregation method that enables improved representation of the road conditions just before accident occurrences in order to evaluate the impact of a potential speed limit increase on the UK motorways (e.g. from 70 mph to 80 mph). In this work, accidents are aggregated according to the similarity of their pre-accident traffic and geometric conditions, forming an alternative accident count dataset termed as the condition-based approach. Accident-speed relationships are separately developed and compared for both approaches (i.e. link-based and condition-based) by employing the reported annual accidents that occurred on the Strategic Road Network of England in 2012 along with traffic and geometric variables. Accident locations were refined using a fuzzy-logic-based algorithm designed for the study area with 98.9% estimated accuracy. The datasets were modelled by injury severity (i.e. fatal and serious or slight) and by number of vehicles involved (i.e. single-vehicle and multiple-vehicle) using the multivariate Poisson lognormal regression, with spatial effects for the link-based model under a full Bayesian inference method. The results of the condition-based models imply that single-vehicle accidents of all severities and multiple-vehicle accidents with fatal or serious injuries increase at higher speed conditions, particularly when these are combined with lower volumes. Multiple-vehicle slight injury accidents were not found to be related with higher speeds, but instead with congested traffic. The outcomes of the link-based model were almost the opposite; suggesting that the speed-accident relationship is negative. The differences between the results reveal that data aggregation may be crucial, yet so far overlooked in the methodological aspect of accident data analyses. By employing the speed elasticity of motorway accidents that was derived from the calibrated condition-based models it has been found that a 10 mph increase in UK motorway speed limit (i.e. from 70 mph to 80 mph) would result in a 6-12% increase in fatal and serious injury accidents and 1-3% increase in slight injury accidents.

Esta pesquisa apresenta uma proposta de reconstrução de matriz OD a partir de dados de velocidade da corrente de tráfego disponíveis na web. Para tal, foram estabelecidos três objetivos específicos, os quais incluem: obtenção e avaliação dos dados de velocidade de tráfego; construção de um modelo computacional e aplicação desse em uma rede real. A avaliação dos dados foi realizada por meio da comparação dos valores de velocidade média da corrente de tráfego obtidos da web com os valores aferidos por sensores do tipo laço indutivo. Os resultados indicam que, apesar das velocidades extraídas da web apresentarem maior variância e valores mais baixos, a maior parcela dos dados obteve diferença similar ou inferior a 11%. Na construção da rotina computacional foi utilizado o Método das Médias Sucessivas (MEMS) e na sua avaliação foram realizados testes comparativos cujas referências foram os resultados alcançados pelo autor do método utilizado. A rotina desenvolvida apresentou melhor resultado com relação ao número total de viagens da matriz reconstruída, além de exigir menor número de iterações. Por outro lado, com relação às viagens atribuídas a cada par OD seu desempenho foi inferior. Para avaliar a aderência a realidade o método proposto foi aplicado a uma rede real composta por trechos específicos das rodovias Presidente Dutra, Pedro I, Ayrton Senna e Governador Carvalho Pinto. Devido ao fato da entrada principal do MEMS ser o volume de veículos, foi necessário estimar o mesmo a partir da velocidade fornecida pela API. A matriz reconstruída apresentou forte dependência da capacidade atribuída às vias, evidenciando a necessidade de definir de forma mais cuidadosa esse parâmetro. Embora, ainda seja necessário aprimorar o método proposto e a rotina computacional elaborada, bem como, aprofundar os estudos da fonte de dados utilizada, o experimento de caráter exploratório mostra a possibilidade de reconstruir uma matriz OD a partir de dados disponíveis na web. / This research presents a proposal for the reconstruction of OD matrix from traffic stream velocity data available on the web. To this end, three specific objectives have been established, which include: obtaining and evaluating traffic speed data; construction of a computational model and application of this in a real network. The data were evaluated by the comparison of the mean values of the traffic current, obtained from the web, with those measured by loop sensors. The results indicate that, although the velocities extracted from the web presented higher variance and lower values, the greater part of the data obtained a difference similar to or lower than 11%. In the construction of the computational routine was used the Method of Successive Averages (MEMS) and in its evaluation were performed comparative tests whose references were the results achieved by the author of the used method. The developed routine presented better results in relation to the total number of trips of the reconstructed OD matrix, besides requiring a smaller number of iterations. On the other hand, in relation to the trips attributed to each OD pair the performance was lower. To evaluate the adherence to reality, the proposed method was applied to a real network composed of specific sections of the Presidente Dutra, Pedro I, Ayrton Senna and Governador Carvalho Pinto highways. Due to the fact that the main input of the MEMS is the vehicles flow, was necessary to estimate it from the speed provided by the API. The reconstructed matrix presented a strong dependence on the capacity attributed to the roads, evidencing the need to define this parameter more carefully. Although it is still necessary to improve the proposed method and the elaborated computational routine, as well as to deepen the studies of the used data source, the exploratory experiment shows the possibility of reconstructing an OD matrix from data available on the web.

Esta pesquisa apresenta uma proposta de reconstrução de matriz OD a partir de dados de velocidade da corrente de tráfego disponíveis na web. Para tal, foram estabelecidos três objetivos específicos, os quais incluem: obtenção e avaliação dos dados de velocidade de tráfego; construção de um modelo computacional e aplicação desse em uma rede real. A avaliação dos dados foi realizada por meio da comparação dos valores de velocidade média da corrente de tráfego obtidos da web com os valores aferidos por sensores do tipo laço indutivo. Os resultados indicam que, apesar das velocidades extraídas da web apresentarem maior variância e valores mais baixos, a maior parcela dos dados obteve diferença similar ou inferior a 11%. Na construção da rotina computacional foi utilizado o Método das Médias Sucessivas (MEMS) e na sua avaliação foram realizados testes comparativos cujas referências foram os resultados alcançados pelo autor do método utilizado. A rotina desenvolvida apresentou melhor resultado com relação ao número total de viagens da matriz reconstruída, além de exigir menor número de iterações. Por outro lado, com relação às viagens atribuídas a cada par OD seu desempenho foi inferior. Para avaliar a aderência a realidade o método proposto foi aplicado a uma rede real composta por trechos específicos das rodovias Presidente Dutra, Pedro I, Ayrton Senna e Governador Carvalho Pinto. Devido ao fato da entrada principal do MEMS ser o volume de veículos, foi necessário estimar o mesmo a partir da velocidade fornecida pela API. A matriz reconstruída apresentou forte dependência da capacidade atribuída às vias, evidenciando a necessidade de definir de forma mais cuidadosa esse parâmetro. Embora, ainda seja necessário aprimorar o método proposto e a rotina computacional elaborada, bem como, aprofundar os estudos da fonte de dados utilizada, o experimento de caráter exploratório mostra a possibilidade de reconstruir uma matriz OD a partir de dados disponíveis na web. / This research presents a proposal for the reconstruction of OD matrix from traffic stream velocity data available on the web. To this end, three specific objectives have been established, which include: obtaining and evaluating traffic speed data; construction of a computational model and application of this in a real network. The data were evaluated by the comparison of the mean values of the traffic current, obtained from the web, with those measured by loop sensors. The results indicate that, although the velocities extracted from the web presented higher variance and lower values, the greater part of the data obtained a difference similar to or lower than 11%. In the construction of the computational routine was used the Method of Successive Averages (MEMS) and in its evaluation were performed comparative tests whose references were the results achieved by the author of the used method. The developed routine presented better results in relation to the total number of trips of the reconstructed OD matrix, besides requiring a smaller number of iterations. On the other hand, in relation to the trips attributed to each OD pair the performance was lower. To evaluate the adherence to reality, the proposed method was applied to a real network composed of specific sections of the Presidente Dutra, Pedro I, Ayrton Senna and Governador Carvalho Pinto highways. Due to the fact that the main input of the MEMS is the vehicles flow, was necessary to estimate it from the speed provided by the API. The reconstructed matrix presented a strong dependence on the capacity attributed to the roads, evidencing the need to define this parameter more carefully. Although it is still necessary to improve the proposed method and the elaborated computational routine, as well as to deepen the studies of the used data source, the exploratory experiment shows the possibility of reconstructing an OD matrix from data available on the web.