Heavy traffic volumes in peak hours accompanied by closely located signalized intersections and nearside bus stops on U.S. 1, result in congestion and traffic delays that bus transit may be able to alleviate to some extent. The capital investment and operating costs of other transit solutions such as "Bus Rapid Transit" and "Heavy Rail Transit" projects were found to be cost prohibitive compared to bus transit signal priority (TSP) options. Successful implementation of a limited TSP pilot project led local authorities to conclude that TSP should be extended to the full length of the Fairfax Connector bus routes on U.S. 1. This research focused on testing the impacts of a ten second green extension priority strategy for all the northbound transit buses in the morning peak period at twenty-six signalized intersections along U.S. 1. A micro simulation model VISSIM 3.7 was used to analyze the impacts of TSP. The simulation analysis indicates that the Fairfax Connector buses might benefit from the green extension strategy. Overall, improvements of up to 4% for transit travel time savings and 5-13% reduction in control delay for transit vehicles were observed. Considering all side street traffic, the total increase in maximum queue length might be up to 1.23%. Future research possibilities proposed include the evaluation of different priority strategies such as an early green, red truncation and queue jumps. Impacts of using a dedicated lane for transit buses along with TSP can also be evaluated. Conditional transit signal priority may also include bus occupancy levels and bus latenesses. / Master of Science

Microscopic traffic simulation software have gained significant popularity and are widely used both in industry and research mainly because of the ability of these tools to reflect the dynamic nature of the transportation system in a stochastic fashion. To better utilize these software, it is necessary to understand the underlying logic and differences between them. A Car-following model is the core of every microscopic traffic simulation software. In the context of this research, the thesis develops procedures for calibrating the steady-state car-following models in a number of well known microscopic traffic simulation software including: CORSIM, AIMSUN, VISSIM, PARAMICS and INTEGRATION and then compares the VISSIM and INTEGRATION software for the modeling of traffic signalized approaches. The thesis presents two papers. The first paper develops procedures for calibrating the steady-state component of various car-following models using macroscopic loop detector data. The calibration procedures are developed for a number of commercially available microscopic traffic simulation software, including: CORSIM, AIMSUN2, VISSIM, Paramics, and INTEGRATION. The procedures are then applied to a sample dataset for illustration purposes. The paper then compares the various steady-state car-following formulations and concludes that the Gipps and Van Aerde steady-state car-following models provide the highest level of flexibility in capturing different driver and roadway characteristics. However, the Van Aerde model, unlike the Gipps model, is a single-regime model and thus is easier to calibrate given that it does not require the segmentation of data into two regimes. The paper finally proposes that the car-following parameters within traffic simulation software be link-specific as opposed to the current practice of coding network-wide parameters. The use of link-specific parameters will offer the opportunity to capture unique roadway characteristics and reflect roadway capacity differences across different roadways. Second, the study compares the logic used in both the VISSIM and INTEGRATION software, applies the software to some simple networks to highlight some of the differences/similarities in modeling traffic, and compares the various measures of effectiveness derived from the models. The study demonstrates that both the VISSIM and INTEGRATION software incorporate a psycho-physical car-following model which accounts for vehicle acceleration constraints. The INTEGRATION software, however uses a physical vehicle dynamics model while the VISSIM software requires the user to input a vehicle-specific speed-acceleration kinematics model. The use of a vehicle dynamics model has the advantage of allowing the model to account for the impact of roadway grades, pavement surface type, pavement surface condition, and type of vehicle tires on vehicle acceleration behavior. Both models capture a driver's willingness to run a yellow light if conditions warrant it. The VISSIM software incorporates a statistical stop/go probability model while current development of the INTEGRATION software includes a behavioral model as opposed to a statistical model for modeling driver stop/go decisions. Both software capture the loss in capacity associated with queue discharge using acceleration constraints. The losses produced by the INTEGRATION model are more consistent with field data (7% reduction in capacity). Both software demonstrate that the capacity loss is recovered as vehicles move downstream of the capacity bottleneck. With regards to fuel consumption and emission estimation the INTEGRATION software, unlike the VISSIM software, incorporates a microscopic model that captures transient vehicle effects on fuel consumption and emission rates. / Master of Science

Esta pesquisa traz à discussão a implantação de Sistemas Inteligentes de Transportes (ITS), em particular a funcionalidade Transit Signal Priority (TSP), ou Prioridade Semafórica, como uma solução a ser considerada para melhorar o desempenho de um corredor de ônibus. Os dados do Sistema Integrado de Monitoramento (SIM) foram empregados para identificar os locais com maior retardamento no Corredor Campo Limpo - Rebouças- Centro em São Paulo e, selecionado um trecho crítico, foi elaborada uma rede de microssimulação no software PTV - Vissim. A aplicação da prioridade semafórica foi feita através do VISVAP, controlador de lógica externo, no qual foram escritas as condicionantes de prioridade. O TSP foi simulado em quatro cenários distintos e, os resultados obtidos permitiram concluir que as expectativas verificadas no referencial teórico (por exemplo: aumento da velocidade média dos ônibus e automóveis), puderam ser comprovadas e, além disso, a prioridade semafórica condicional foi capaz de reduzir os retardos inclusive nas vias transversais não priorizadas. / This research brings to discussion the implementation of Intelligent Transportation Systems (ITS), particularly the Transit Signal Priority (TSP) feature as a solution to be considered to improve the performance of a bus corridor. Data from a Monitoring Integrated System (Sistema Integrado de Monitoramento - SIM) were used to identify most significant delay points at Campo Limpo - Rebouças- Centro Corridor in São Paulo and, after selected a critical stretch, it was developed a microsimulation with PTV Vissim software. The transit signal priority was made by VISVAP, external logic controller, in which were described the priority conditions. TSP was simulated in four different scenarios and, the obtained results have concluded that expectations examined in academic referencial (for example: increase in the average speed of buses and cars), could be confirmed, and, in addition, the transit signal priority was able to decrease delays in cross ways too (not prioritized).

Esta pesquisa traz à discussão a implantação de Sistemas Inteligentes de Transportes (ITS), em particular a funcionalidade Transit Signal Priority (TSP), ou Prioridade Semafórica, como uma solução a ser considerada para melhorar o desempenho de um corredor de ônibus. Os dados do Sistema Integrado de Monitoramento (SIM) foram empregados para identificar os locais com maior retardamento no Corredor Campo Limpo - Rebouças- Centro em São Paulo e, selecionado um trecho crítico, foi elaborada uma rede de microssimulação no software PTV - Vissim. A aplicação da prioridade semafórica foi feita através do VISVAP, controlador de lógica externo, no qual foram escritas as condicionantes de prioridade. O TSP foi simulado em quatro cenários distintos e, os resultados obtidos permitiram concluir que as expectativas verificadas no referencial teórico (por exemplo: aumento da velocidade média dos ônibus e automóveis), puderam ser comprovadas e, além disso, a prioridade semafórica condicional foi capaz de reduzir os retardos inclusive nas vias transversais não priorizadas. / This research brings to discussion the implementation of Intelligent Transportation Systems (ITS), particularly the Transit Signal Priority (TSP) feature as a solution to be considered to improve the performance of a bus corridor. Data from a Monitoring Integrated System (Sistema Integrado de Monitoramento - SIM) were used to identify most significant delay points at Campo Limpo - Rebouças- Centro Corridor in São Paulo and, after selected a critical stretch, it was developed a microsimulation with PTV Vissim software. The transit signal priority was made by VISVAP, external logic controller, in which were described the priority conditions. TSP was simulated in four different scenarios and, the obtained results have concluded that expectations examined in academic referencial (for example: increase in the average speed of buses and cars), could be confirmed, and, in addition, the transit signal priority was able to decrease delays in cross ways too (not prioritized).

In order to improve the air quality in Uppsala, a proposition to introduce one of two new emission zones (EZ), starting in the year 2020, has been proposed. In what is called Environment Zone Class 2 (EZ2), only cars that meet emission class Euro 5 and higher are allowed and in Environment Zone Class 3 (EZ3), only electric, fuel cell and gas vehicles are allowed. The purpose of this thesis is to examine how EZ: s would affect the air quality, regarding nitrogen oxides (NOx) and particles (PMx), within the zone of the city of Uppsala. Using the traffic simulation software PTV Vissim and the emissions modeling software EnViver, four scenarios have been created, two representing today's fleet of vehicles and two examining a modified fleet. Scenario 1 examines an exclusion of all non EZ2 vehicles (Euro 4 and lower) within the zone and scenario 2 examines an EZ2 solely on the road Kungsgatan. Scenario 3 and 4 examine an EZ2 and EZ3 where all cars that do not currently meet the requirements for each EZ are replaced with ones that do. The results indicate that all proposals, except scenario 2, lead to a reduction of NOx and PM2 within the zone. Scenario 1 shows a decrease by 51% for NOx and 57% for PM10, scenario 3 shows a decrease by 17% and 24% respectively and scenario 4 shows a decrease by 66% and 43% respectively. For scenario 2 the emissions show an increase by 10% and 7% each within the zone.

Advanced Driver Assistance Systems (ADAS) offer the possibility of helping drivers to fulfill their driving tasks. Automated vehicles are capable of communicating with surrounding vehicles (V2V) and infrastructure (V2I) in order to collect and provide essential information about driving environment. Studies have proved that automated vehicles have a potential to decrease traffic congestion on road networks by reducing the time headway, enhancing the traffic capacity and improving the safety margins in car following. Furthermore, vehicle movement and driver’s behavior of conventional vehicles will be affected by the presence of automated vehicles in traffic networks. Despite different encouraging factors, automated driving raises some concerns such as possible loss of situation awareness, overreliance on automation and degrading driving skills in absence of practice. Moreover, coping with complex scenarios, such as merging at ramps and overtaking, in terms of interaction between automated vehicles and conventional vehicles need more research. This thesis work aims to investigate the effects of automated vehicles on driver’s behavior and traffic performance. A broad literature review in the area of driving simulators and psychological studies was performed to examine the automated vehicle effects on driver’s behavior. Findings from the literature survey, which has been served as setup values in the simulation study of the current work, reveal that the conventional vehicles, which are driving close to the platoon of automated vehicles with short time headway, tend to reduce their time headway and spend more time under their critical time headway. Additionally, driving highly automated vehicles is tedious in a long run, reduce situation awareness and can intensify driver drowsiness, exclusively in light traffic. In order to investigate the influences of automated vehicles on traffic performance, a microscopic simulation case study consisting of different penetration rates of automated vehicles (0, 50 and 100 percentages) was conducted in VISSIM software. The scenario network is a three-lane autobahn segment of 2.9 kilometers including an off-ramp, on-ramp and a roundabout with some surrounding urban roads. Outputs of the microscopic simulation in this study reveal that the positive effects of automated vehicles on roads are especially highlighted when the network is crowded (e.g. peak hours). This can definitely count as a constructive point for the future of road networks with higher demands. In details, average density of autobahn segment remarkably decreased by 8.09% during p.m. peak hours in scenario with automated vehicles. Besides, Smoother traffic flow with less queue in the weaving segment was observed. Result of the scenario with 50% share of automated vehicles moreover shows a feasible interaction between conventional vehicles and automated vehicles. Meaningful outputs of this case study, based on the input data from literature review, demonstrate the capability of VISSIM software to simulate the presence of automated vehicles in great extent, not only as an automated vehicle scenario but also a share of them, in traffic network. The validity of the output values nonetheless needs future research work on urban and rural roads with different traffic conditions.

Freeway merging VISSIM calibration techniques were developed for the analysis of ramp metering in Georgia. An analysis of VISSIM’s advanced merging and cooperative lane change settings was undertaken to determine their effects on merging behavior. Another analysis was performed to determine the effects of the safety reduction factor and the maximum deceleration for cooperative braking parameter on the simulated merging behavior. Results indicated that having both the advanced merging and cooperative lane change setting active produced the best results and that the safety reduction factor had more influence on the merging behavior than the maximum deceleration for cooperative braking parameter. Results also indicated that the on-ramp experienced unrealistic congestion when on-ramp traffic was unable to immediately find an acceptable gap when entering the acceleration lane. These vehicles would form a queue at the end of the acceleration lane and then be unable to merge into the freeway lane due to the speed differential between the freeway and the queued ramp traffic. An Incremental Desired Speed algorithm was developed to maintain an acceptable speed differential between the merging traffic and the freeway traffic. The Incremental Desired Speed algorithm resulted in a smoother merging behavior. Lastly, a ramp meter was introduced and an increase in both the freeway throughput and overall speeds was found. Implications of these findings on the future research is discussed.

Traffic safety is one of the most essential aspects of transportation engineering. However, most crash prediction models are statistically-based prediction methods, which require significant efforts in crash data collection and may not be applied in particular traffic environments due to the limitation of data sources. Traditional traffic conflict studies are mostly field-based studies depending on manual counting, which is also labor-intensive and oftentimes inaccurate. Nowadays, simulation tools are widely utilized in traffic conflict studies. However, there is not a surrogate indicator that is widely accepted in conflict studies. The primary objective of this research is to develop such a reliable surrogate measure for simulation-based conflict studies. An indicator named Aggregated Crash Propensity Index (ACPI) is proposed to address this void. A Probabilistic model named Crash Propensity Model (CPM) is developed to determine the crash probability of simulated conflicts by introducing probability density functions of reaction time and maximum braking rates. The CPM is able to generate the ACPI for three different conflict types: crossing, rear-end and lane change. A series of comparative and field-based analysis efforts are undertaken to evaluate the accuracy of the proposed metric. Intersections are simulated with the VISSIM micro simulation and the output is processed through SSAM to extract useful conflict data to be used as the entry into CPM model. In the comparative analysis, three studies are conducted to evaluate the safety effect of specific changes in intersection geometry and operations. The comparisons utilize the existing Highway Safety Manual (HSM) processes to determine whether ACPI can identify the same trends as those observed in the HSM. The ACPI outperforms time-to-collision-based indicators and tracks the values suggested by the HSM in terms of identifying the relative safety among various scenarios. In field-based analysis, the Spearman’s rank tests indicate that ACPI is able to identify the relative safety among traffic facilities/treatments. Moreover, ACPI-based prediction models are well fitted, suggesting its potential to be directly link to real crash. All efforts indicate that ACPI is a promising surrogate measure of safety for simulation-based studies.

Técnicas como a harmonização da velocidade procuram gerir e controlar o tráfego com base nas condições de tráfego das rodovias em tempo real. A harmonização da velocidade utiliza limites de velocidade variáveis (L.V.V.) para fornecer aos condutores uma velocidade de operação mais apropriada, normalmente inferior ao limite de velocidade estático indicado, em resposta as condições dinâmicas das vias. O L.V.V. tem demonstrado capacidade de melhorar a mobilidade e a segurança nas rodovias. Com isso, modelos de avaliação de risco de colisão em tempo real são frequentemente adotados para quantificar os riscos de ocorrência de colisões em estudos de implantação do L.V.V. Na maioria dos estudos sobre L.V.V., modelos de probabilidade de colisão são adotados apenas para mensurar o desempenho do sistema. Estes algoritmos de controle de L.V.V. não levam em conta o risco de colisões em períodos futuros, e assim não usam impactos do L.V.V. para escolher o plano de controle com relação à segurança. No Brasil, estratégias de harmonização da velocidade não são empregadas. Como as condições de tráfego nas rodovias brasileiras não são homogêneas, e cada faixa de tráfego normalmente possui médias de velocidades, intensidades de fluxo e composições de tráfego diferentes, técnicas como o L.V.V Podem oferecer benefícios ao harmonizar as velocidades entre as faixas e assim retardar o aparecimento de congestionamentos, reduzir o número de ultrapassagens e o risco de colisões. Dessa forma, este trabalho busca avaliar a relação entre as características do tráfego e a probabilidade de ocorrer conflitos entre veículos, para assim desenvolver um modelo matemático capaz de expressar tal relação – usando como estudo de caso um trecho da rodovia BR-290/RS, situada na região metropolitana da cidade de Porto Alegre. Este modelo matemático alimenta um algoritmo L.V.V., empregado em um micro simulador de tráfego, para controlar o tráfego com o objetivo de aumentar a segurança. Resultados indicam que o modelo proposto classificou corretamente 87% dos conflitos efetivamente ocorridos em campo. Os resultados de simulação indicam que o emprego do sistema L.V.V. contribuiu significativamente para a redução da probabilidade de conflitos. Ainda, o L.V.V. aumentou as velocidades médias nos períodos de fluxo elevado, e também reduziu o desvio padrão das velocidades – oferecendo um tráfego mais homogêneo – que contribui para a redução do número de trocas de faixa e, consequentemente, para um aumento da segurança. / Techniques such as speed harmonization seek to manage and control traffic based on road traffic conditions in real time. Speed harmonization uses variable speed limits (VSL) to provide drivers with a more appropriate speed, usually below the stated static speed limit, in response to dynamic road conditions. The VSL has demonstrated its ability to improve mobility and road safety. Thus, real-time collision risk assessment models are often adopted to quantify the risk of collisions occurring in VSL implantation studies. In most VSL studies, collision probability models are utilized only to measure the system performance. These VSL control algorithms do not take into account the risk of collisions in future periods, and thus do not use the VSL impacts to choose the control plan concerning safety. In Brazil, Speed harmonization strategies are not employed yet. As the traffic conditions on Brazilian highways are not homogeneous, and each traffic range usually has different average speeds, flow intensities, and traffic compositions, VSL techniques can offer benefits by harmonizing speeds between lanes, slowing down congestion, reducing the number of overtaking and the risk of collisions.( Continue) Thus, this work seeks to evaluate the relationship between traffic characteristics and the probability of conflicts between vehicles, in order to develop a mathematical model capable of expressing such a relation - using as a case the BR-290/RS freeway, located in the Porto Alegre metropolitan area. This mathematical model will then feed a VSL algorithm, employed in a micro traffic simulator, to control traffic and increase safety. Results indicate that the proposed model correctly classified 87% of the conflicts actually occurred in the field. The simulation results indicate that the VSL contributed significantly to reducing the conflicts likelihood. Even more, the VSL increased the average speeds for high flow periods, and also reduced the standard deviation of speeds - offering a more homogeneous traffic - which contributes for reduction in the number of lane changes and, consequently, to an increase in safety.

In a traditional safety impact analysis, it is necessary to have crash data on existing roadway conditions in the field and a few years must pass before accumulating reliable crash data. This is a time-consuming approach and there remains uncertainty in the crash data due to the random nature of crash occurrences. The Surrogate Safety Assessment Model (SSAM) was developed for resolving these issues. With SSAM, a conflict analysis is performed in a simulated environment. A planned improvement alternative under study is modeled and no physical installation of the alternative is needed. Hence, the method using a simulation software along with SSAM consumes less time compared to other traditional safety analysis methods that may require a physical installation of the new alternative and a long wait time for data collection. The purpose of this study is to evaluate if SSAM can be used to assess the safety of a highway segment or an intersection in term of the number and type of conflicts and to compare the safety effects of multiple access management alternatives with less time, less cost and less uncertainty than the traditional safety analysis methods. To meet the purpose of the study, two study sections, one on University Parkway in Orem and Provo and the other on Main Street in American Fork were selected and analyzed in this research. Based on the findings from the calibration of SSAM on the University Parkway study section, an evaluation of the effect of converting a TWLTL median into a raised median on a section of Main Street (US-89) from 300 West to 500 East in American Fork was performed using SSAM working on VISSIM simulation's trajectory files of the study section. This evaluation study was conducted to show how SSAM could be used to evaluate the effect of access management alternatives using surrogate safety measures. The analysis showed that a raised median would be much safer than a TWLTL median for the same level of traffic volume. Approximately a 32 to 50 percent reduction in the number of crossing conflicts was achieved when a raised median was used in lieu of a TWLTL median at the Main Street study section.