Research in the field of travel time measurement using Bluetooth technology has been an area of great interest in recent years as transportation professionals strive to increase the cost-effectiveness, accuracy, anonymity, and safety of travel time data collection methods. Commonly used travel time data collection methods include the use of inductive loops, video cameras, and probe vehicles. However, Bluetooth, a globally accepted wireless technology, serves as the medium being utilized by more and more transportation consultants, public agencies, and academics in the collection of travel time data. This study seeks to develop a methodology for measuring travel times on arterial roads using Bluetooth technology. A literature review of general travel time methods and Bluetooth travel time methods was conducted to provide the context for a Bluetooth field deployment development and implementation. The study presents the deployment plan and data analysis of a case study conducted on Spring Street in Atlanta, Georgia. Variable heights, Bluetooth to Bluetooth interference, and detection of Bluetooth devices in probe vehicles are investigated and recommendations are suggested for future Bluetooth travel time studies.

This study examines the safety effects of the improvements made on multi-lane arterials. The improvements were divided into two categories 1) corridor level improvements, and 2) intersection improvements. Empirical Bayes method, which is one of the most accepted approaches for conducting before-after evaluations, has been used to assess the safety effects of the improvement projects. Safety effects are estimated not only in terms of all crashes but also rear-end (most common type) as well as severe crashes (crashes involving incapacitating and/or fatal injuries) and also angle crashes for intersection improvements. The Safety Performance Functions (SPFs) used in this study are negative binomial crash frequency estimation models that use the information on ADT, length of the segments, speed limit, and number of lanes for corridors. And for intersections the explanatory variables used are ADT, number of lanes, speed limit on major road, and number of lanes on the minor road. GENMOD procedure in SAS was used to develop the SPFs. Corridor SPFs are segregated by crash groups (all, rear-end, and severe), length of the segments being evaluated, and land use (urban, suburban and rural). The results of the analysis show that the resulting changes in safety following corridor level improvements vary widely. Although the safety effect of projects involving the same type of improvement varied, the overall effectiveness of each of the corridor level improvements were found to be positive in terms of reduction in crashes of each crash type considered (total, severe, and rear-end) except for resurfacing projects where the total number of crashes slightly increased after the roadway section is resurfaced. Evaluating additional improvements carried out with resurfacing activities showed that all (other than sidewalk improvements for total crashes) of them consistently led to improvements in safety of multilane arterial sections. It leads to the inference that it may be a good idea to take up additional improvements if it is cost effective to do them along with resurfacing. It was also found that the addition of turning lanes (left and/or right) and paving shoulders were two improvements associated with a project�s relative performance in terms of reduction in rear-end crashes. No improvements were found to be associated with a resurfacing project�s relative performance in terms of changes in (i.e., reducing) severe crashes. For intersection improvements also the individual results of each project varied widely. Except for adding turn lane(s) all other improvements showed a positive impact on safety in terms of reducing the number of crashes for all the crash types (total, severe, angle, and rear-end) considered. Indicating that the design guidelines for this work type have to be revisited and safety aspect has to be considered while implementing them. In all it can be concluded that FDOT is doing a good job in selecting the sites for treatment and it is very successful in improving the safety of the sections being treated although the main objective(s) of the treatments are not necessarily safety related.

The methodology to measure the performance of urban streets was significantly revised in the latest edition of the Highway Capacity Manual (HCM 2010). Urban Streets, which include urban and suburban signalized arterial highways, typically serve the four modes of transportation (auto, transit, pedestrian and bicycle) and are frequently congested. Analyzing both recurrent and non-recurrent conditions is essential. In this dissertation, the author addressed several urban streets related issues by developing an alternative method to measure recurrent multimodal conditions on urban streets; gathering feedback relating to the key elements of the developed method; and developing a probabilistic method to analyze and measure non-recurrent conditions. Real life sample applications were performed for both developed methods. The developed multimodal method addresses the following: (1) the use of level of service (LOS) step functions; (2) the comparability of LOS results across modes; (3) the impacts of modes on other modes; (4) the establishment of thresholds; (5) accuracy; and (6) user perceptions in measuring multimodal conditions on urban streets. Feedback gathered from transportation professionals through focus group meetings and surveys supported most of the features of the developed multimodal method and provided default values for method application. They were divided on the naming of condition levels and on the number of condition levels to use. Non-recurrent conditions were addressed through the development of a Markovian probabilistic method to analyze and measure the resilience of congested, signalized, arterial highways, for which availability of existing analytical tools is limited. The method results provide a plexiform of information about the rate and speed of recovery of the arterial traffic flow. / Ph. D.

Since before the release of the Highway Safety Manual research has been indicating the need to incorporate mobility and control aspects to road safety analysis. The first part of this work developed and implement in an existing computational engine a signal timing optimization method that considers mobility, safety, and emissions measures simultaneously. A sensitivity analysis was conducted to provide insight on the practical effects and order of relevance of 20 key input variables. Mobility improvement performance usually coincides with emissions improvements, but sometimes at the expense of safety. The second part of this work investigated the relationship between hourly traffic density and crash rates on Brazilian expressways with different characteristics, based on a database containing over 20,000 crashes and more than 35 million traffic volume observations and. The resulting curves for urban expressways follow a U shape, with minimum values associated with LOS B to C, while the relationships for rural expressways were found to be continuously increasing, suggesting that low volume rural roads are safer than the higher volume ones. The analysis of other influencing factors revealed that nighttime conditions, weaving segments and urban multilane highways could be related to higher crash rates. The third part of the project extends the analysis to crash severity modeling, using an ordered response choice model. The framework that better fit this database led to the development of two different models: single-vehicle crashes (SV) and multiple-vehicle crashes (MV), since the factors that explain the severity of crashes varies widely between these models. For instance, guardrails and barriers proved to effectively reduce severity for SV crashes, for which run-offs are the most severe crash type. The unique database used in this study also allowed for an investigation of the influence of prevailing traffic conditions on crash severity, while still controlling for all other factors. The results suggested that multiple-vehicle crash severity is negatively related with traffic density, while single-vehicle crashes are more closely related to speed. The findings of this work have implications to policy and design decisions, and the produced equation could be incorporated to active traffic management (ATM) and HCM reliability analysis. / Desde antes da publicação do Highway Safety Manual, vários pesquisadores indicam a necessidade de se incorporar aspectos de operação de tráfego à análise de segurança viária. A primeira parte deste trabalho desenvolveu e implementou em uma ferramenta computacional existente um método de otimização de tempos semafóricos que considera medidas de desempenho de operação, segurança e emissões simultaneamente. Uma análise de sensibilidade foi realizada para produzir conhecimento sobre os efeitos práticos e a ordem de relevância de 20 variáveis de entrada principais. O desempenho da programação semafórica em termos de redução dos atrasos geralmente coincide com redução das emissões, embora às vezes às custas da segurança. A segunda parte deste trabalho investigou a relação entre a densidade horária de tráfego e as taxas de acidentes em autoestradas e rodovias de pista dupla brasileiras com características diversas, com base em um banco de dados contendo mais de 20.000 registros de acidentes e mais de 35 milhões de observações de tráfego. As curvas resultantes para rodovias urbanas seguem um formato em U, com valores mínimos associados aos níveis de serviço B a C, enquanto que as relações para as rodovias rurais são contínuas e crescentes, sugerindo que rodovias rurais de baixo volume são mais seguras do que as de maior volume. A análise de outros fatores revelou que condições noturnas, segmentos de entrelaçamento e rodovias de pista dupla convencionais urbanas estariam relacionadas a maiores taxas de acidentes. A terceira parte deste projeto amplia a análise para modelagem de severidade dos acidentes, usando um modelo de escolha discreta ordenado. A estrutura que melhor se adequa a esse banco de dados levou ao desenvolvimento de dois modelos diferentes: acidentes com um veículo e acidentes com múltiplos veículos, já que os fatores que explicam a severidade dos acidentes variam muito entre esses modelos. Por exemplo, defensas e barreiras se mostraram efetivas para a redução da severidade de acidentes com um veículo, para as quais a saída de pista é o tipo de acidente mais grave. O amplo banco de dados usado neste estudo também permitiu uma investigação da influência das condições de tráfego na severidade do acidente, em comparação com todos os outros fatores. Os resultados sugeriram que a severidade de acidentes de múltiplos veículos está negativamente relacionada com a densidade de tráfego, enquanto colisões com um único veículo estão mais relacionadas à velocidade. As descobertas deste trabalho têm implicações nas decisões sobre políticas e projetos de transportes, e a equação produzida pode ser incorporada à análise de confiabilidade do gerenciamento ativo do tráfego (ATM) e do Highway Capacity Manual.

Since before the release of the Highway Safety Manual research has been indicating the need to incorporate mobility and control aspects to road safety analysis. The first part of this work developed and implement in an existing computational engine a signal timing optimization method that considers mobility, safety, and emissions measures simultaneously. A sensitivity analysis was conducted to provide insight on the practical effects and order of relevance of 20 key input variables. Mobility improvement performance usually coincides with emissions improvements, but sometimes at the expense of safety. The second part of this work investigated the relationship between hourly traffic density and crash rates on Brazilian expressways with different characteristics, based on a database containing over 20,000 crashes and more than 35 million traffic volume observations and. The resulting curves for urban expressways follow a U shape, with minimum values associated with LOS B to C, while the relationships for rural expressways were found to be continuously increasing, suggesting that low volume rural roads are safer than the higher volume ones. The analysis of other influencing factors revealed that nighttime conditions, weaving segments and urban multilane highways could be related to higher crash rates. The third part of the project extends the analysis to crash severity modeling, using an ordered response choice model. The framework that better fit this database led to the development of two different models: single-vehicle crashes (SV) and multiple-vehicle crashes (MV), since the factors that explain the severity of crashes varies widely between these models. For instance, guardrails and barriers proved to effectively reduce severity for SV crashes, for which run-offs are the most severe crash type. The unique database used in this study also allowed for an investigation of the influence of prevailing traffic conditions on crash severity, while still controlling for all other factors. The results suggested that multiple-vehicle crash severity is negatively related with traffic density, while single-vehicle crashes are more closely related to speed. The findings of this work have implications to policy and design decisions, and the produced equation could be incorporated to active traffic management (ATM) and HCM reliability analysis. / Desde antes da publicação do Highway Safety Manual, vários pesquisadores indicam a necessidade de se incorporar aspectos de operação de tráfego à análise de segurança viária. A primeira parte deste trabalho desenvolveu e implementou em uma ferramenta computacional existente um método de otimização de tempos semafóricos que considera medidas de desempenho de operação, segurança e emissões simultaneamente. Uma análise de sensibilidade foi realizada para produzir conhecimento sobre os efeitos práticos e a ordem de relevância de 20 variáveis de entrada principais. O desempenho da programação semafórica em termos de redução dos atrasos geralmente coincide com redução das emissões, embora às vezes às custas da segurança. A segunda parte deste trabalho investigou a relação entre a densidade horária de tráfego e as taxas de acidentes em autoestradas e rodovias de pista dupla brasileiras com características diversas, com base em um banco de dados contendo mais de 20.000 registros de acidentes e mais de 35 milhões de observações de tráfego. As curvas resultantes para rodovias urbanas seguem um formato em U, com valores mínimos associados aos níveis de serviço B a C, enquanto que as relações para as rodovias rurais são contínuas e crescentes, sugerindo que rodovias rurais de baixo volume são mais seguras do que as de maior volume. A análise de outros fatores revelou que condições noturnas, segmentos de entrelaçamento e rodovias de pista dupla convencionais urbanas estariam relacionadas a maiores taxas de acidentes. A terceira parte deste projeto amplia a análise para modelagem de severidade dos acidentes, usando um modelo de escolha discreta ordenado. A estrutura que melhor se adequa a esse banco de dados levou ao desenvolvimento de dois modelos diferentes: acidentes com um veículo e acidentes com múltiplos veículos, já que os fatores que explicam a severidade dos acidentes variam muito entre esses modelos. Por exemplo, defensas e barreiras se mostraram efetivas para a redução da severidade de acidentes com um veículo, para as quais a saída de pista é o tipo de acidente mais grave. O amplo banco de dados usado neste estudo também permitiu uma investigação da influência das condições de tráfego na severidade do acidente, em comparação com todos os outros fatores. Os resultados sugeriram que a severidade de acidentes de múltiplos veículos está negativamente relacionada com a densidade de tráfego, enquanto colisões com um único veículo estão mais relacionadas à velocidade. As descobertas deste trabalho têm implicações nas decisões sobre políticas e projetos de transportes, e a equação produzida pode ser incorporada à análise de confiabilidade do gerenciamento ativo do tráfego (ATM) e do Highway Capacity Manual.