Actualmente, existe un incremento vehicular en Lima Metropolitana que perjudica la eficacia de las vías de comunicación terrestres. Por tal motivo, el presente tema de investigación tiene como finalidad reducir el grado de saturación en las intersecciones urbanas de la Av. Angamos Este con Av. Aviación, Av. Tomás Marsano y Av. República de Panamá ubicadas en Lima Metropolitana a través de la metodología Ramp Metering que considera desarrollar el algoritmo ALINEA. En primera instancia, se describió la situación actual de los cruces viales previamente mencionados, a partir del reconocimiento en campo. Posteriormente, se recopilaron los tiempos de verde efectivo vehicular y el ciclo semafórico peatonal. De igual manera, se contabilizó presencialmente el flujo de automóviles durante 13 horas continuas y el número de transeúntes en las intersecciones durante el mismo periodo. Subsiguientemente, se evaluaron las condiciones de circulación existente, donde el principal objetivo es determinar el grado de saturación por medio de flujogramas que permiten una mejor visualización del estado actual. Luego de lo mencionado, se empleó la estrategia ALINEA para diseñar una propuesta de mejora a partir los tiempos de verde efectivo calculados el algoritmo mencionado. Siguiendo con el procedimiento, se evaluó el diseño con el software PTV VISSIM 9.0, un programa de micro simulación acorde con los lineamientos planteados del proyecto, con la finalidad de verificar si existe una mejora relacionada al grado de saturación. Por último, se compararon las dos situaciones previstas, calculando el parámetro indicado con el programa VISSIM. / Currently, there is an exponential growth in the number of vehicles in Metropolitan Lima that harms the efficiency of the vehicle flow on the roads and highways of this city. For this reason, the present research topic aims to reduce the degree of saturation at the urban intersections of Av. Angamos Este with Av. Aviación, Av. Tomás Marsano and Av. República de Panamá located in Metropolitan Lima through the methodology of Ramp Metering that considers developing the ALINEA algorithm. In the first instance, the current situation of the previously mentioned crosses was described based on the recognition carried out in the field. Subsequently, the effective vehicular green times and the pedestrian traffic light cycle will be collected. In the same way, the traffic flow was collected for 13 consecutive hours and the number of passers-by at the intersections during the same period. Subsequently, the existing circulation conditions were evaluated, where the main objective is to determine the degree of saturation throughout flow charts that allow a better visualization of the current state. After the aforementioned, ALINEA strategy was used to design a proposal that improves the vehicle flow of the intersections based on the effective green times calculated by the algorithm mentioned. Following the procedure, the design is evaluated with the PTV VISSIM 9.0 software, a micro simulation program in accordance with the guidelines outlined in the project, with the purpose of verifying if there is an improvement related to the degree of saturation. Finally, the two situations foreseen were compared, calculating the indicated parameter with the arithmetic process of the micro simulator VISSIM. / Tesis

Diamond interchanges and their associated ramps are where the surface street arterial system and the freeway system interface. Historically, these two elements of the system have been operated with little or no coordination between the two. Therefore, there is a lack of both analysis tools and operational strategies for considering them as an integrated system. One drawback of operating the ramp-metering system and the diamond interchange system in isolation is that traffic from the ramp, particularly if it is metered, can spill back into the diamond interchange, causing both congestion and safety concerns at the diamond interchange. While flushing the ramp queues by temporarily suspending ramp metering has been the primary strategy for preventing queue spillback, it can result in freeway system breakdown, which would affect the entire system's efficiency. The aim of this research was to develop operational strategies for managing an integrated diamond interchange ramp-metering system (IDIRMS). Enhanced modeling methodologies were developed for an IDIRMS. A computer model named DRIVE (Diamond Interchange and Ramp Metering Integration Via Evaluation) was developed, which was characterized as a mesoscopic simulation and analysis model. DRIVE incorporated the enhanced modeling methodologies developed in this study and could be used to perform system analysis for an IDIRMS given a set of system input parameters and variables. DRIVE was validated against a VISSIM microscopic simulation model, and general agreement was found between the two models. System operational characteristics were investigated using DRIVE to gain a better understanding of the system features. Integrated control strategies (ICS) were developed based on the two commonly used diamond interchange phasing schemes, basic three-phase and TTI four-phase. The ICS were evaluated using VISSIM microscopic simulation under three general traffic demand scenarios: low, medium, and high, as characterized by the volume-to-capacity ratios at the metered ramps. The results of the evaluation indicate that the integrated operations through an adaptive signal control system were most effective under the medium traffic demand scenario by preventing or delaying the onset of ramp-metering queue flush, thereby minimizing freeway breakdown and system delays.

Diamond interchanges and their associated ramps are where the surface street arterial system and the freeway system interface. Historically, these two elements of the system have been operated with little or no coordination between the two. Therefore, there is a lack of both analysis tools and operational strategies for considering them as an integrated system. One drawback of operating the ramp-metering system and the diamond interchange system in isolation is that traffic from the ramp, particularly if it is metered, can spill back into the diamond interchange, causing both congestion and safety concerns at the diamond interchange. While flushing the ramp queues by temporarily suspending ramp metering has been the primary strategy for preventing queue spillback, it can result in freeway system breakdown, which would affect the entire system's efficiency. The aim of this research was to develop operational strategies for managing an integrated diamond interchange ramp-metering system (IDIRMS). Enhanced modeling methodologies were developed for an IDIRMS. A computer model named DRIVE (Diamond Interchange and Ramp Metering Integration Via Evaluation) was developed, which was characterized as a mesoscopic simulation and analysis model. DRIVE incorporated the enhanced modeling methodologies developed in this study and could be used to perform system analysis for an IDIRMS given a set of system input parameters and variables. DRIVE was validated against a VISSIM microscopic simulation model, and general agreement was found between the two models. System operational characteristics were investigated using DRIVE to gain a better understanding of the system features. Integrated control strategies (ICS) were developed based on the two commonly used diamond interchange phasing schemes, basic three-phase and TTI four-phase. The ICS were evaluated using VISSIM microscopic simulation under three general traffic demand scenarios: low, medium, and high, as characterized by the volume-to-capacity ratios at the metered ramps. The results of the evaluation indicate that the integrated operations through an adaptive signal control system were most effective under the medium traffic demand scenario by preventing or delaying the onset of ramp-metering queue flush, thereby minimizing freeway breakdown and system delays.

Thesis (Ph. D. in Engineering)--University of California, Berkeley, 2005. / "May 2005." Includes bibliographical references (p. 64-66). Also available online via the ITS Berkeley web site (www.its.berkeley.edu).

Research recently conducted at the University of Central Florida involving crashes on Interstate-4 in Orlando, Florida has led to the creation of new statistical and neural networks models that are capable of determining the crash risk on the freeway (Abdel-Aty et al., 2004; 2005, Pande and Abdel-Aty, 2006). These models are able to calculate rear-end and lane-change crash risks along the freeway in real-time through the use of static information at various locations along the freeway as well as real-time traffic data obtained by loop detectors. Since these models use real-time traffic data, they are capable of calculating rear-end and lane-change crash risk values as the traffic flow conditions are changing on the freeway. The objective of this study is to examine the potential benefits of combining two ITS strategies (Ramp Metering and Variable Speed Limits strategies) for reducing the crash risk (both rear-end and lane-change crash risks) along the I-4 freeway. Following this aspect, a 36.25-mile section of I-4 running though Orlando, FL was simulated using the PARAMICS micro-simulation program. Gayah (2006) used the same network to examine the potential benefits of two ITS strategies separately (Route Diversion and Ramp Metering) for reducing the crash risk along the freeway by changing traffic flow parameters. Cunningham (2007) also used the same network to examine the potential benefits of implementing Variable Speed Limits strategy for reducing the crash risk along the freeway. Since the same network is used, the calibration and validation procedures used in this study are the same as these previous two studies. This study simulates three volume loading scenarios on the I-4 freeway. These are 60, 80 and 90 percent loading scenarios. From the final experimental design for the 60 % loading, it was concluded that implementing VSL strategy only was more beneficial to the network than either implementing Ramp Metering everywhere (through the whole network) in conjunction with VSL everywhere or implementing Ramp Metering downtown (in downtown areas only) in conjunction with VSL everywhere. This was concluded from the comparison of the results of this study with the results from Cunningham (2007). However, either implementing Ramp Metering everywhere or downtown in conjunction with VSL everywhere showed safety benefits across the simulated network as well as a reduction in the total travel time. The best case for implementing Ramp Metering everywhere in conjunction with VSL everywhere was using a homogeneous speed zone threshold of 2.5 mph, a speed change distance of half speed zone and a speed change time of 5 minutes in conjunction with a 60 seconds cycle length for the Zone algorithm, a critical occupancy of 0.17 and a 30 seconds cycle length for the ALINEA algorithm. And the best case for implementing Ramp Metering downtown in conjunction with VSL everywhere was using a homogeneous speed zone threshold of 2.5 mph, a speed change distance of half speed zone and a speed change time of 10 minutes in conjunction with a 60 seconds cycle length for the Zone algorithm, a critical occupancy of 0.17 and a 30 seconds cycle length for the ALINEA algorithm. For the 80 % loading, it was concluded that either implementing Ramp Metering everywhere in conjunction with VSL everywhere or implementing Ramp Metering downtown in conjunction with VSL everywhere was more beneficial to the network than implementing VSL strategy only. This was also concluded from the comparison of the results of this study with the results from Cunningham (2007). Moreover, it was concluded that implementing Ramp Metering everywhere in conjunction with VSL everywhere showed higher safety benefits across the simulated network than implementing Ramp Metering downtown in conjunction with VSL everywhere. Also, both of them increased the total travel time a bit, but this was deemed acceptable. Additionally, both of them had successive fluctuations and variations in the average lane-change crash risk vs. time step. The best case for implementing Ramp Metering everywhere in conjunction with VSL everywhere was using a homogeneous speed zone threshold of 5 mph, a speed change distance of half speed zone and a speed change time of 30 minutes in conjunction with a 60 seconds cycle length for the Zone algorithm, a critical occupancy of 0.17 and a 30 seconds cycle length for the ALINEA algorithm. And the best case for implementing Ramp Metering downtown in conjunction with VSL everywhere was using a homogeneous speed zone threshold of 5 mph, a speed change distance of half speed zone and a speed change time of 30 minutes in conjunction with a 60 seconds cycle length for the Zone algorithm, a critical occupancy of 0.17 and a 30 seconds cycle length for the ALINEA algorithm. Searching for the best way to implement both Ramp Metering and VSL strategies in conjunction with each other, an indepth investigation was conducted in order to remove the fluctuations and variations in the crash risk with time step (through the entire simulation period). The entire simulation period is 3 hours, and each time step is 5 minutes, so there are 36 time steps representing the entire simulation period. This indepth investigation led to the idea of not implementing VSL at consecutive zones (using either a gap of one zone or more). Then this idea was applied for the best case of implementing Ramp Metering and VSL everywhere at the 80 % loading, and the successive fluctuations and variations in the crash risk with time step were removed. Moreover, much better safety benefits were found. So, this confirms that this idea was very beneficial to the network. For the 90 % loading, it was concluded that implementing Ramp Metering strategy only (Zone algorithm in downtown areas, and ALINEA algorithm in non downtown areas) was more beneficial to the network than implementing Ramp Metering everywhere in conjunction with VSL everywhere. This was concluded from the comparison of the results of this study with the results from Gayah (2006). However, implementing Ramp Metering everywhere in conjunction with VSL everywhere showed safety benefits across the simulated network as well as a reduction in the total travel time. The best case was using a homogeneous speed zone threshold of 2.5 mph, a speed change distance of the entire speed zone and a speed change time of 20 minutes in conjunction with a 60 seconds cycle length for the Zone algorithm, a critical occupancy of 0.17 and a 30 seconds cycle length for the ALINEA algorithm. In summary, Ramp Metering was more beneficial at congested situations, while Variable Speed Limits were more beneficial at free-flow conditions. At conditions approaching congestion, the combination of Ramp Metering and Variable Speed Limits produced the best benefits. These results illustrate the significant potential of ITS strategies to improve the safety and efficiency of urban freeways.

Increasing demand on freeway facilities is a major challenge facing urban areas in the United States and throughout the world. Active Traffic Management (ATM) strategies can be used to increase the performance of these facilities through improved operations without the significant expenditure associated with adding capacity. One ATM strategy that has been widely deployed in the current state of practice is ramp metering, which controls the traffic demand placed on a freeway. Merge control strategies are less prevalent and largely undeveloped. This study examines the recurrently congested northbound section of Interstate Highway 35 that approaches downtown Austin, Texas. Using the VISSIM microsimulation platform, a model of this segment was developed and calibrated to reflect current peak-hour congestion. Within this model, ramp metering and merge control technologies were implemented. The impacts on traffic throughput, speed and travel time for each of these proposed systems are evaluated. / text

Urban freeway demand that frequently exceeds capacity has caused many agencies to consider many options to reduce congestion. A series of solutions that falls under the Active Traffic Management (ATM) banner have shown promising potential. Perhaps the most popular ATM strategy is ramp metering. Ramp metering involves limiting the access of vehicles to freeways at an entrance ramp. By doing this, freeway throughput, speeds, and travel time reliability can be increased, while the number of traffic incidents can be decreased. This study examines the application of an innovative ramp metering strategy, Intersection Ramp Metering (IRM), at a section of Loop 1 in Austin, TX. IRM implements the ramp metering function at the intersection immediately upstream of the entrance ramp, rather than on the ramp itself. A microsimulation analysis of this application is performed in VISSIM, and the results confirm that freeway throughput (+10%), and system average travel time (-14%), can be improved, as well as several other performance measures. / text

No description available.

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.

La thèse présente les résultats de recherche sur une méthode de contrôle distribué et coordonné pour la régulation des accès autoroutiers. Le trafic autoroutier est représenté par le modèle Cell Transmission Model (CTM). L'objectif de contrôle principal est de d'obtenir une distribution uniforme de la densité des véhicules sur des portions d'autoroute. Équilibrer la densité est un nouvel objectif de trafic qui peut potentiellement réduire le nombre et l'intensité des accélérations et décélérations et peut par conséquent permettre des voyages plus sécurisés et confortables tout en diminuant la consommation de carburant et les émissions de polluants. En outre, cet objectif prend en compte les paramètres de trafic standards tels que le Temps de Trajet Total et la Distance Totale Parcourue. Une architecture modulaire distribuée est proposée pour le contrôleur. Cela permet de déterminer les décisions optimales à prendre en utilisant uniquement des informations d'état locales et en provenance des contrôleurs voisins.La contribution débute par l'analyse d'ensembles d'équilibre de CTM. L'objectif de cette étude est d'obtenir les conditions qui assurent l'existence et l'unicité des états stationnaire qui sont équilibrées. Dans l'ensemble des états stationnaire, nous sommes intéressés à la sélection du point qui maximise la Distance Totale Parcourue. Sont discutés ensuite les aspects de la mise en œuvre et les limites de la méthode proposée. Enfin, plusieurs études de cas sont présentées appuyant les résultats d'analyse et examinant l'efficacité de la méthode proposée.La majeure partie de la thèse vise à concevoir un dispositif de commande optimale pour équilibrer la densité du trafic routier. L'optimisation est réalisée de manière répartie. En utilisant les propriétés de contrôlabilité, l'ensemble des sous-systèmes devant être contrôlés par des feux aux rampes d'accès sont identifiés. Le problème d'optimisation est alors formulé comme de Nash du jeu dans un environnement non coopératif. Le jeu est résolu en le décomposant en une série de jeux à deux joueurs hiérarchiques et compétitifs. Le processus d'optimisation emploie des canaux de communication qui correspond à la structure de commutation de l'interconnexion de système. L'approche alternative pour équilibrer emploie la théorie des systèmes multi-agents. Chacun des contrôleurs est pourvu d'une structure à rétroaction assurant que les états au sein de son sous-système atteignent des valeurs communes par l'évaluation de protocoles de consensus. Dans ces structures, un problème de contrôle optimal minimisant le Temps de Trajet Total est formulé. Le contrôleur distribué fondé sur le jeu de Nash est validé grâce des simulations microscopiques Aimsun. Le scénario de test comprend des données de trafic provenant de la rocade sud de Grenoble. / The thesis presents the results of research on distributed and coordinated control method for freeway ramp metering. The freeway traffic is represented by the Cell-Transmission Model. The primary control objective is to provide a uniform distribution of vehicle densities over freeway links. Density balancing is a new traffic objective which can potentially reduce the number and intensity of acceleration and deceleration events and therefore, it can make a travel more safety and comfortable while decreasing fuel consumption and emissions. In addition, the objective takes into account standard traffic metrics like Total Travel Distance and Total Travel Spent. For the controller, a distributed modular architecture is assumed. It enables to compute the optimal decisions by using only local state information and some supplementary information arriving from the neighbouring controllers.The contributing part begins with the analysis on equilibrium sets of the Cell-Transmission Model. The goal of this study is to derive the conditions that assure the existence and the uniqueness of the balanced equilibrium states. The next step is to find a set of inputs such that the resulting equilibrium state is balanced. In the set of balanced equilibria, we are interested in the selection of the point that maximizes the Total Travel Distance. In the sequel, the implementation aspects and limitations of the proposed method are discussed. Finally, several case studies are presented to support the analysis results and to examine the effectiveness of the proposed method.The major part of the thesis aims on a design of an optimal controller for balancing the traffic density. The optimization is performed in a distributed manner. By using controllability properties, the set of subsystems to be controlled by local ramp meters are identified. The optimization problem is then formulated as a non-cooperative Nash game. The game is solved by decomposing it into a set of two-players hierarchical and competitive games. The process of optimization employs the communication channels matching the switching structure of system interconnectivity. The alternative approach of balancing employs the theory of multi-agent systems. Each of the controllers is provided with a feedback structure assuring that the states within its local subsystem achieve common values by evaluating consensus protocols. Under these structures, an optimal control problem to minimize the Total Travel Spent is formulated. The distributed controller based on the Nash game is validated via Aimsun micro-simulations. The testing scenario involves the traffic data collected from the south ring of Grenoble.