Evaluation of critical transportation infrastructure and their operation is vital for continuous evolution to meet the growing needs of the society with time. The current practice of evaluating signalized intersections has two steps. The first is to determine the level of service at which the intersection is performing. Level of Service (LOS) is based on the average delay per vehicle that gets past the particular intersection under consideration. The second step is to do a capacity analysis. This considers the number of lanes and other infrastructure related factors and also includes the influence of the control strategies. The above-described procedure evaluates any one intersection at a time. It is necessary to compare and rank a given set of intersections for planning purposes such as choosing the sites for improvements. The research work presented in this thesis demonstrates how Data Envelopment Analysis (DEA) can be used as a tool to achieve the purpose of comparing and ranking a given set of comparable intersections. This study elaborates on various ways of representing different characteristics of an intersection. The demonstration has been restricted to four way signalized intersections. The intersections that were used for demonstration as part of this research were created in a controlled random fashion by simulation. / Master of Science

No description available.

Consecutive traffic signals produce vehicle stops and acceleration/deceleration maneuvers on arterial roads, which may increase vehicle fuel consumption levels significantly. Eco-cooperative adaptive cruise control (Eco-CACC) systems can improve vehicle energy efficiency using connected vehicle (CV) technology. In this thesis, an Eco-CACC system is proposed to compute a fuel-optimized vehicle trajectory while traversing multiple signalized intersections. The proposed system utilizes signal phasing and timing (SPaT) information together with real-time vehicle dynamics data to compute the optimal acceleration/deceleration levels and cruise speeds for connected-technology-equipped vehicles while approaching and leaving signalized intersections, while considering vehicle queues upstream of the intersections. The INTEGRATION microscopic traffic simulation software was used to conduct a comprehensive sensitivity analysis of a set of variables, including different levels of CV market penetration rates (MPRs), demand levels, phase splits, offsets, and distances between intersections to assess the benefits of the proposed algorithm. Based on the analysis, fuel consumption saving increase with an increase in MPRs and a decrease in the cycle length. At a 100% equipped-vehicle MPR, the fuel consumption is reduced by as much as 13.8% relative to the base no Eco-CACC control. The results demonstrate an existence of optimal values for demand levels and the distance between intersections to reach the maximum fuel consumption reduction. Moreover, if the offset is near the optimal values for that specific approach, the benefits from the algorithm are reduced. The algorithm is limited to under-saturated conditions, so the algorithm should be enhanced to deal with over-saturated conditions. / Master of Science / Consecutive traffic signals produce vehicle stops and acceleration/deceleration maneuvers on arterial roads, increasing vehicle fuel consumption levels. Drivers approaching signals are unaware of the signal status and may accelerate/decelerate aggressively to respond to traffic signal indications and thus increasing their fuel consumption. Research has been conducted to provide the driver with an optimal speed recommendations to reduce fuel consumption. Connected vehicle (CV) technology can be used to create a communication between the vehicle and traffic signals to provide information about the traffic light status and how many vehicles are waiting in the queue. In this thesis, an Eco-cooperative adaptive cruise control (Eco-CACC) system is proposed, which is a system that uses signal information to provide speed advice to the driver. This speed advice will not make the vehicle stop at any intersection, and this will reduce fuel consumption levels. The INTEGRATION software was used to test the effectiveness of the system in many scenarios. These scenarios include how many vehicles are equipped with this system, how many vehicles are in the system, the length of the green interval of the traffic signal, and distance between intersections. If we equip all vehicles with the system, the savings in fuel consumption can reach up to 13.8%. The system is designed for a network that is not extremely congested (over-saturated), implying that queues dissipate in a single traffic light cycle. The system needs to be further developed to deal with over-saturated conditions.

The development of driver assistance and automated vehicle control is in process and finds its way more and more into urban traffic environments. Here, the complexity of traffic situations is highly challenging and requires system approaches to comprehend such situations. The key element is the process of situation assessment to identify critical situations in advance and derive adequate warning and intervention strategies. This thesis introduces a system approach to establish a situation assessment process with the focus on the prediction of the driver intention. The system design is based on the Situation Awareness model by Endsley. Further, a prediction algorithm is created using Hidden Markov Models. To define the parameters of the models, an existing database is used and previously analyzed to identify reasonable variables that indicate an intended driving direction while approaching the intersection. Here, vehicle dynamics are used instead of driver inputs to enable a further extension of the prediction, i.e.\\ to predict the driving intention of other vehicles detected by sensors. High prediction rates at temporal distances of several seconds before entering the intersection are accomplished. The prediction is integrated in a system for situation assessment including an intersection model. A Matlab tool is created with an interface to the vehicle CAN bus and the intersection modeling which uses digital map data to establish a representation of the intersection. To identify differences and similarities in the process of approaching an intersection dependent on the intersection shape and regulation, a naturalistic driving study is conducted. Here, the distance to the intersection and velocity is observed on driver inputs related to the upcoming intersection (leaving the gas pedal, pushing the brake, using the turn signal). The findings are used to determine separate prediction models dependent on shape and regulation of the upcoming intersection. The system runs in real-time and is tested in a real traffic environment. / Die Entwicklung von Fahrerassistenz und automatisiertem Fahren ist in vollem Gange und entwickelt sich zunehmend in Richtung urbanen Verkehrsraum. Hier stellen besonders komplexe Verkehrssituationen sowohl für den Fahrer als auch für Assistenzsysteme eine Herausforderung dar. Zur Bewältigung dieser Situationen sind neue Systemansätze notwendig, die eine Situationsanalyse und -bewertung beinhalten. Dieser Prozess der Situationseinschätzung ist der Schlüssel zum Erkennen von kritischen Situationen und daraus abgeleiteten Warnungs- und Eingriffsstrategien. Diese Arbeit stellt einen Systemansatz vor, welcher den Prozess der Situationseinschätzung abbildet mit einem Fokus auf die Prädiktion der Fahrerintention. Das Systemdesign basiert dabei auf dem Situation Awareness Model von Endsley. Der Prädiktionsalgorithmus ist mit Hilfe von Hidden Markov Modellen umgesetzt. Zur Bestimmung der Modellparameter wurde eine existierende Datenbasis genutzt und zur Bestimmung von relevanten Variablen für die Prädiktion der Fahrtrichtung während der Kreuzungsannäherung analysiert. Dabei wurden Daten zur Fahrdynamik ausgewählt anstelle von Fahrereingaben um die Prädiktion später auf externe Fahrzeuge mittels Sensorinformationen zu erweitern. Es wurden hohe Prädiktionsraten bei zeitlichen Abständen von mehreren Sekunden bis zum Kreuzungseintritt erzielt. Die Prädiktion wurde in das System zur Situationseinschätzung integriert. Weiterhin beinhaltet das System eine statische Kreuzungsmodellierung. Dabei werden digitale Kartendaten genutzt um eine Repräsentation der Kreuzung und ihrer statischen Attribute zu erzeugen und die der Kreuzungsform entsprechenden Prädiktionsmodelle auszuwählen. Das Gesamtsystem ist als Matlab Tool mit einer Schnittstelle zum CAN Bus implementiert. Weiterhin wurde eine Fahrstudie zum natürlichen Fahrverhalten durchgeführt um mögliche Unterschiede und Gemeinsamkeiten bei der Annäherung an Kreuzungen in Abhängigkeit der Form und Regulierung zu identifizieren. Hierbei wurde die Distanz zur Kreuzung und die Geschwindigkeit bei Fahrereingaben im Bezug zur folgenden Kreuzung gemessen (Gaspedalverlassen, Bremspedalbetätigung, Blinkeraktivierung). Die Ergebnisse der Studie wurden genutzt um die Notwendigkeit verschiedener Prädiktionsmodelle in Abhängigkeit von Form der Kreuzung zu bestimmen. Das System läuft in Echtzeit und wurde im realen Straßenverkehr getestet.

The safety at half-signalized intersections in Portland, Oregon is analyzed in this thesis using 10 years of crash history and analysis of video that was collected at a subset of intersections. A half-signalized intersection has a standard red-yellow-green traffic signal for automobiles on the major road, a stop sign for motorists on the minor road, and a pedestrian signal with actuation for pedestrians and/or bicyclists on the minor road. Although prevalent in Canada, this type of intersection control is not typically found in the United States because the MUTCD explicitly prohibits its use. Half-signal use is limited mostly to two cities in the Pacific Northwest. In Portland, Oregon there are forty-seven intersections where half-signals are used but the last installation was in 1986; Seattle has over 100 intersections with half-signals and installs these in new locations where warranted. To explore the safety records of these intersections in Portland, crash data from 2002-2011 was analyzed. A total of 442 crashes over the ten-year period at half-signals were observed. Sixteen of these 442 crashes involved pedestrians. In the crashes involving pedestrians, significant differences were found between the approach street of the vehicle and whether the pedestrian or driver was at fault. In the crash error reports, it was found that significantly more of the crashes involving pedestrians were the fault of motorists departing from the minor road who collided with pedestrians crossing the major street. Further crash analysis at half-signals was performed by developing matched comparison groups of minor stop controlled and fully signalized intersections. Crash rates were 0.158 and 0.178 crashes per million entering vehicles for 3-leg and 4-leg half-signals and these rates did not differ significantly from the minor street stop controlled and signalized comparison groups. Results from the matched comparison showed that the half-signalized group had more rear-end crashes when compared with the minor stop controlled group. This was the only result that held significance when crash rates were considered. It was also observed that the minor stop controlled group had a higher proportion of angle crashes when compared with the half-signal group but this did not influence the crash severity. Pedestrian crashes were more prevalent in the half-signal group when compared with the fully-signalized group. Pedestrian volumes were not available which would be used to determine if this significant measure is a result of higher pedestrian use at half-signals. In addition to crash analysis, video was captured at five half-signalized intersections totaling 180 hours. Traffic volumes, pedestrian and bicycle volumes, and signal actuations were collected over a twenty-four hour period. Over this twenty-four hour period the five intersections averaged daily counts of 18613 vehicles on the major street, 591 vehicles on the minor street, 263 pedestrians crossing the major street, 285 pedestrians crossing the minor street, 52 bicycles on the major street, 37 bicycles on the minor street, and 126 signal actuations. Twenty-four hour observations from each of the intersections were used to study conflicts and compliance. No conflicts were observed that reflect the left-turning from the minor street pedestrian crashes that were identified in the crash history. Compliance of the half-signal by vehicles and pedestrians was comparable to compliance at fully-signalized intersections found in other studies with one exception. Across the intersections where video was collected, consisting of four 4-leg intersections and one 3-leg intersection, seven left turn on red violations were observed which had a significant impact on the time after red that red light violations were made. It is hypothesized that at half-signals vehicles on the major street make a left turn on the red signal very late into the red phase because there is not a risk of colliding with a vehicle traveling on the minor street since traffic volumes on the minor street are comparably low. The observed left turn on red violations did not put pedestrians at risk since by that point into the signal pedestrians were already clear of the intersection. Finally, a stop compliance logistic regression model was developed at four four-leg intersections to see what factors had an effect on minor street vehicle stop compliance. All 166 hours of video were used to observe vehicles that arrived at the half-signal during the pedestrian phase. The dependent variable collected was whether a vehicle came to an acceptable stop. Independent variables collected included the vehicle's queue position, if it was the peak school period, if there was a vehicle across the street on the minor road, if a vehicle was stopped at the signal on the major street, if a pedestrian was present when the vehicle arrived, and the movement that the vehicle made from the minor street. Independent variables used in the model included the vehicle's queue position, if a vehicle was stopped at the signal on the major street, if a pedestrian was present, and if the vehicle made a right turn at the signal. Pedestrian presence and right turning vehicles had a positive impact on stop compliance. Vehicles being further back in the queue and cars stopped at the signal on the major street had a negative impact on stop sign compliance. In the model, pedestrian presence had the largest positive impact on stop compliance. When pedestrians were present, a motorist on the minor street was four times more likely to stop at the sign.

Dans cette thèse on s'intéresse au temps local d'auto-intersections de marches aléatoires. Cette quantité est définie comme la norme-p à la puissance p du temps local de la marche. Elle regarde dans quelle mesure la trajectoire de la marche aléatoire s'intersecte. Le temps local d'auto-intersections est lié à différents modèles physiques comme les modèles de polymères ou les problèmes d'écoulements de flux en milieux stratifiés mais aussi au modèle mathématiques des marches aléatoires en paysages aléatoires. Nous nous sommes pour notre part intéressés en particulier aux grandes déviations du temps local d'auto-intersections, c'est à dire que nous regardons la probabilité que la quantité d'intersections de la marche aléatoire soit plus grande que sa moyenne. Cette question qui a été très étudiée au cours des années 2000 fait apparaitre trois cas distincts, le cas sous-critique, le cas critique et le cas sur-critique. Nous améliorons la connaissance sur cette question au travers de deux résultats complets et d'un résultat partiel. D'abord nous prouvons un principe de grandes déviations dans les cas critique et sur-critique des marches alpha-stables, puis nous améliorons les échelles de déviations au cas sous-critique tout entier de la marche simple, enfin nous sommes en train d'étendre ce dernier résultat aux marches alpha-stables. Par ailleurs les trois preuves sont basées sur l'utilisation d'une version due à Eisenbaum d'un théorème d'isomorphisme de Dynkin. Cette méthode d'abord introduite par Castell dans le cas critique est donc ici étendue aux autres cas. Nous avons donc réussi à unifier les différentes méthodes de preuves au travers ce théorème d'isomorphisme. / In this thesis we are interested in the self-intersection local times of random walks. This quantity is defined as the p-norm to the power of p of the local times of the random walk. It measures how much the trajectory of the random walk intersects itself. The self-intersection local times is connected with various physical models as polymer models or problems of anomalous dispersion in layered random flows, but it is also linked with the mathematical model of random walks in random sceneries. More precisely, we are interested in the large deviations of the self-intersection local times, i.e. we work on the probability for the intersections to be larger than expected. This question that has been studied a lot during the 2000's is divided in three cases, the subcritical one, the critical one and the super critical one. We improve the knowledge about this question by two complete results and a partial one. First, we have proved a large deviation principle in the critical and super critical cases of alpha-stable random walks, then we have improved the deviations' scales to the entire subcritical case of simple random walk, finally we are extending this last result to the alpha-stable random walks. The three proofs are based on a version due to Eisenbaum of a Dynkin isomorphism theorem. This method which has been first introduced by Castell in the critical case, is extended here to the others cases. Thus, we have succeeded to unify the methods of proof by this isomorphism theorem.

La régulation adaptative des feux de signalisation est un problème très important. Beaucoup de chercheurs travaillent continuellement afin de résoudre les problémes liés à l’embouteillage dans les intersections urbaines. Il devient par conséquent très utile d’employer des algorithmes intelligents afin d’améliorer les performances de régulation et la qualité du service. Dans cette thèse, nous essayons d'étudier ce problème d’une part à travers une modèlisation microscopique et dynamique en temps discret, et d’autre part en explorant plusieurs approches de résoltion pour une intersection isolée ainsi que pour un réseau distribué d'intersections.La première partie se concentre sur la modélisation dynamique des problèmes des feux de signalisation ainsi que de la charge du réseau d’intersections. Le mode de la “séquence de phase adaptative” (APS) dans un plan de feux est d'abord considéré. Quant à la modélisation du contrôle des feux aux intersections, elle est formulée grâce à un processus décisionnel de markov (MDP). En particulier, la notion de “l'état du système accordable” est alors proposée pour la coordination du réseau de trafic. En outre, un nouveau modèle de “véhicule-suiveur” est proposé pour l'environnement de trafic. En se basant sur la modélisation proposée, les méthodes de contrôle des feux dans cette thèse comportent des algorithmes optimaux et quasi-optimaux. Deux algorithmes exacts de résolution basées sur la programmation dynamique (DP) sont alors étudiés et les résultats montrent certaines limites de cette solution DP surtout dans quelques cas complexes où l'espace d'états est assez important. En raison de l’importance du temps d’execution de l'algorithme DP et du manque d'information du modèle (notamment l’information exacte relative à l’arrivée des véhicules à l’intersection), nous avons opté pour un algorithme de programmation dynamique approximative (ADP). Enfin, un algorithme quasi-optimal utilisant l'ADP combinée à la méthode d’amélioration RLS-TD (λ) est choisi. Dans les simulations, en particulier avec l'intégration du mode de phase APS, l'algorithme proposé montre de bons résultats notamment en terme de performance et d'efficacité de calcul. / Adaptive traffic signal control is a decision making optimization problem. People address this crucial problem constantly in order to solve the traffic congestion at urban intersections. It is very popular to use intelligent algorithms to improve control performances, such as traffic delay. In the thesis, we try to study this problem comprehensively with a microscopic and dynamic model in discrete-time, and investigate the related algorithms both for isolated intersection and distributed network control. At first, we focus on dynamic modeling for adaptive traffic signal control and network loading problems. The proposed adaptive phase sequence (APS) mode is highlighted as one of the signal phase control mechanisms. As for the modeling of signal control at intersections, problems are fundamentally formulated by Markov decision process (MDP), especially the concept of tunable system state is proposed for the traffic network coordination. Moreover, a new vehicle-following model supports for the network loading environment.Based on the model, signal control methods in the thesis are studied by optimal and near-optimal algorithms in turn. Two exact DP algorithms are investigated and results show some limitations of DP solution when large state space appears in complex cases. Because of the computational burden and unknown model information in dynamic programming (DP), it is suggested to use an approximate dynamic programming (ADP). Finally, the online near-optimal algorithm using ADP with RLS-TD(λ) is confirmed. In simulation experiments, especially with the integration of APS, the proposed algorithm indicates a great advantage in performance measures and computation efficiency.

Cette thèse a pour objet l’étude et le contrôle de la photo-réactivité d’interrupteurs moléculaires, en particulier la photo-isomérisation des spiropyranes. Ce travail théorique a été réalisé en collaboration étroite avec l’équipe expérimentale PFL de l’ICB à Dijon. Des simulations de dynamique quantique non-adiabatique ont été réalisées afin de reproduire et rationaliser les résultats expérimentaux de spectroscopie d’absorption transitoire résolue en temps. Ces expériences ont montré une photo-réactivité ultra-rapide (~ 100 fs) suite à une excitation par une pulse LASER ultra-court. Celle-ci est interprétée comme un mécanisme de conversion interne entre le premier état électronique excité singulet et l’état fondamental via une intersection conique. L’étude théorique a utilisé la réaction d’ouverture de cycle du benzopyrane comme modèle. Les développements réalisés ont porté sur : (1) L’exploration du mécanisme réactionnel et le calcul de surfaces d’énergie potentielle via des méthodes de chimie quantique post-CASSCF perturbatives (XMCQDPT2). Cette analyse a montré des résultats variant fortement par rapport à ceux relevés dans la littérature à des niveaux de calcul moins élevés. (2) Le développement d’un modèle de surfaces d’énergie potentielle électronique par la construction d’un hamiltonien diabatique à partir de données ab initio XMCQDPT2. Du fait de l’importante anharmonicité de l’état électronique fondamental, nous avons mis en place une approche effective en rupture avec les études antérieures. (3) La réalisation de simulations de dynamique quantique non-adiabatique par la méthode MCTDH. Les résultats obtenus sont en très bon accord avec les résultats expérimentaux. L’inclusion explicite du pulse LASER a permis de reproduire et de rationaliser l’effet de contrôle par mise en forme d’impulsion observé expérimentalement. Ce travail a ainsi permis la mise en place d’une collaboration et d’un dialogue théorie/expérience effectifs. / This thesis adresses the study and control of the photo-reactivity of molecular switches, here the photo-isomerisation of spiropyrans. This theoretical work has been achieved in close collaboration with the experimental team PFL within the ICB in Dijon. Non-adiabatic quantum dynamics simulations were carried out so as to reproduce and rationalise the experimental results from time-resolved transient absorption spectroscopy. Such experiments have demonstrated ultra-fast photo-reactivity (~ 100 fs) following excitation by an ultra-short LASER pulse. It is interpreted as an internal conversion mechanism between the first singlet excited eletronic state and the ground state via a conical intersection. The theoretical study used the ring-opening reaction of benzopyran as a model. Developments were made regarding: (1) The exploration of the reaction mechanism and the computation of potential energy surfaces with perturbative, post-CASSCF quantum chemistry methods (XMCQDPT2). This investigation showed that results changed significantly compared to those reported in the literature with lower-level calculations. (2) The generation of a diabatic Hamiltonian based on ab initio XMCQDPT2 data. Owing to the significant anharmonicity in the ground electronic state, we designed a new effective approach, quite different from the previous studies. (3) The production of non-adiabatic quantum dynamics simulations using the MCTDH method. The results thus obtained are in excellent agreement with the experimental ones. Including explicitly the LASER pulse allowed us to reproduce and rationalise the action of pulse shaping on control observed in experiments. The present work thus made possible the succesful implementation of a theoretical/experimental collaboration.

Master of Science / Department of Civil Engineering / Sunanda Dissanayake / Construction of by-pass lanes at rural intersections typically has been considered a low-cost safety improvement. Safety analysis utilizes two common approaches to evaluate treatment effectiveness: before-and-after study and cross-sectional study. This research performed paired sample t-test statistical analysis to estimate changes in total of crash frequency, crash rates, EPDO crash frequency, and EPDO crash rates at intersections, three to five years after adding a by-pass lane compared to identical time period before the by-pass lane was added. Crash data between 1990 and 2011 were obtained from Kansas Crash and Analysis Record System (KCARS) maintained by the Kansas Department of Transportation (KDOT). In order to perform a cross-sectional study, intersections with by-pass lanes were compared to intersections with no countermeasures; crash data were obtained for more than 1,100 intersections in the state of Kansas. According to before-and-after study, addition of by-pass lanes improves safety at unsignalized rural intersections; crashes and their severities are reduced after adding by-pass lanes. But, these reductions are not statistically significant under 95% confidence level. However, when considering intersection related crashes, a statistically significant reduction in crash rates is happened after adding by-pass lanes at 3-legged intersections. In cross-sectional study, crashes and their severities are lower at 3-legged intersections with the by-pass lanes versus 3-legged intersections without the by-pass lanes. However, these reductions are not statistically significant under 95% confidence level. When considering 300 feet intersection crash box, statistically significant reductions are happened at 4-legged intersection. In contrast, crashes and their severities increased at 4-legged intersections with the by-pass lanes, but these changes are not statistically significant under 95% confidence level. The Crash Modification Factors were calculated to evaluate safety effectiveness of adding by-pass lanes at unsignalized rural intersections. The calculated CMFs less than 1.0, indicate a reduction in crashes after implementation of by-pass lanes. Finally, this study concluded that expected crashes at intersections with by-pass lanes are lower than intersections without by-pass lanes.

published_or_final_version / abstract / Geography / Master / Master of Philosophy