Traffic Microsimulation Research Articles

Traffic Microsimulation Study to Evaluate the Effect of Type and Spacing of Traffic Calming Devices on Capacity

Traffic calming is widely implemented to improve road safety. However, the implementation of traffic calming devices implies less capacity of cross-town roads. The present research used traffic microsimulation to study the effect of traffic calming devices on the cross-town roads capacity based on different type and spacing of devices. Average delay was calculated. Then, capacity of the road was obtained for a fixed traffic calming device spacing as the flow rate from which delay presented exponential growth. Capacity of a cross-town road varied between 810 and 1300 vehicles per hour and lane with traffic calming devices spacing from 25 to 400 meters.

Traffic Microsimulation Study to Evaluate Freeway Exit Ramps Capacity

Growing traffic in urban and suburban areas has resulted in a demand for freeway exit ramps with higher capacity in order to avoid congestion. The main objective of the paper was to elaborate recommendations about the best exit ramp layout according to different parameters by evaluating capacity. Seven different diverge layouts were analyzed using traffic microsimulation. The average delay of the vehicles among their exit path was calculated on each diverge layout; and the capacity was obtained as the diverging flow from which the average delay grew exponentially. The capacity of each diverge layout varied from 1600 to 2000 vehicles per hour in one-lane exit ramp. The values for two-lane exit ramp were included on the interval [2000,4400] vehicles per hour.

Investigating road safety issues through a microsimulation model

Some papers have been recently presented (Cunto and Saccomanno, 2007; Cunto and Saccomanno, 2008; Saccomanno et al., 2008) on the potential of traffic microsimulation for the analysis of road safety. In particular, studies have confirmed that the reproduction by simulation of user behaviour under different flow and geometric conditions, can identify a potential incident hazard and allow to take appropriate countermeasures at specific points of the road network. The objective of this paper is to assess the validity of this approach and present a new methodology for investigating road safety issues. A calibrated microsimulation model has been developed to analyze vehicle trajectories, and hence vehicle interactions, in some different scenarios and verify traffic safety levels. The microscopic model allows the estimation of road safety performance through a series of indicators (Crash Potential Index, Deceleration Rate to Avoid Crash, Maximum Available Deceleration Rate, Time to Collision, etc.), representing interactions in real time between different pairs of vehicles belonging to the traffic stream. When these indicators take a certain critical value, a possible accident scenario is identified. The validation of the proposed methodology can be done by comparing the value assumed by safety performance indicators in simulated and real scenarios. The microscopic simulation model is also combined with a new video image traffic detection algorithm to detect vehicle trajectories. Microscopic traffic flow parameters obtained by video detection are, in fact, used to calibrate the microsimulation model. The above described methodology has been applied in the analysis of overtaking maneuvers on single lane for direction fast rural roads. Results indicate that the methodology can be useful in the estimation of safety performance indicators and in evaluating traffic control measures.

Bidirectionally Coupled Network and Road Traffic Simulation for Improved IVC Analysis

Recently, many efforts have been made to develop more efficient Inter-Vehicle Communication (IVC) protocols for on-demand route planning according to observed traffic congestion or incidents, as well as for safety applications. Because practical experiments are often not feasible, simulation of network protocol behavior in Vehicular Ad Hoc Network (VANET) scenarios is strongly demanded for evaluating the applicability of developed network protocols. In this work, we discuss the need for bidirectional coupling of network simulation and road traffic microsimulation for evaluating IVC protocols. As the selection of a mobility model influences the outcome of simulations to a great extent, the use of a representative model is necessary for producing meaningful evaluation results. Based on these observations, we developed the hybrid simulation framework Veins (Vehicles in Network Simulation), composed of the network simulator OMNeT++ and the road traffic simulator SUMO. In a proof-of-concept study, we demonstrate its advantages and the need for bidirectionally coupled simulation based on the evaluation of two protocols for incident warning over VANETs. With our developed methodology, we can advance the state-of-the-art in performance evaluation of IVC and provide means to evaluate developed protocols more accurately.

Design and Implementation of a Parallel Queue-Based Traffic Flow Simulation

Today, agent based micro-simulations are widely used in the field of transport planning and 7 traffic management. One important requirement is the ability to simulate large scale scenarios 8 in reasonable time. An obvious approach to reduce the computation time of such scenarios is 9 to use multiple CPU cores. 10 This paper presents the implementation of a parallel queue simulation for MATSim written 11 in Java. Existing parallel traffic micro-simulations are reviewed concerning their paralleliza12 tion approaches as well as the reached performance gains. Various concepts how to model 13 the progress of time and how to distribute computational workload among multiple CPU cores 14 are discussed. Based on an analysis of the MATSim framework regarding its structure, per15 formance and extensibility the concepts for the parallel queue simulation are selected and im16 plemented. Performance tests with different sized scenarios are conducted. An analysis of the 17 results shows that especially for large scale scenarios a significant performance gain is reach18 able.

Modeling Factors Influencing the Capacity of Motorway Merge Sections Controlled by Ramp Metering

This paper focuses on studying factors which are likely to affect motorway merge capacity when ramp metering controls are in use. A newly developed traffic micro-simulation model has been used for this purpose and the well known ALINEA and Demand-Capacity local ramp metering algorithms were integrated within it. Several parameters such as critical occupancy to trigger the signals, position of ramp traffic signals, position of loop detectors and length of ramp were considered. The effectiveness of ramp metering for a range of traffic flow conditions has been tested for various scenarios to show the range of values where ramp metering is beneficial.

Development and Evaluation of a Control System for Regional Traffic Management

Traffic congestion is a worsening problem in metropolitan areas which will require integrated regional traffic control systems to improve traffic conditions. This paper presents a regional traffic control system which can detect incident conditions and provide integrated traffic management during nonrecurrent congestion events. The system combines advanced artificial intelligence techniques with a traffic performance model based on HCM equations. Preliminary evaluation of the control system using traffic microsimulation demonstrates that it has the potential to improve system conditions during traffic incidents. In addition, several enhancements were identified which will make the system more robust in a real traffic control setting. An assessment of the control system elements indicates that there are no substantial technical barriers in implementing this system in a large traffic network.

Comparison and evaluation of emissions for different driving cycles of motorcycles: A note

On board, chassis dynamometer, and traffic micro-simulation emission measurement approaches are common ways of determining vehicle emission factors. Results from these various approaches are, however, significantly affected by factors such as the driving cycle, and engine size used. These variations are examined. Significant deviations in emission factors from regulatory standard are found for different driving cycle conditions and engine sizes for motorcycles in Edinburgh. Emissions of CO and HC measured using a chassis dynamometer over the Edinburgh motorcycle driving cycle, are found to differ from the results when using other measurement approaches.

Traffic Management for Planned Special Events Using Traffic Microsimulation Modeling and Tabletop Exercises

This article describes the use of microsimulation for traffic management of special events, including evacuations and traffic incidents. Specifically, the research employed tabletop exercises using the microsimulation software TransModeler to present traffic management alternatives for special events to stakeholders. The exercises involved analysis of evacuation or egress conditions with current traffic management plans, review of possible high-impact incident scenarios, and testing and formulation of improvements to current traffic management procedures, including incident response. Two case studies were developed for the tabletop exercises; one the evacuation of a minor-league baseball stadium and another concerned with vehicular egress plans for a large urban indoor arena. Both venues were in New York State's Capital District region. The results demonstrated that the real-time use of microsimulation during a tabletop exercise elicited many new traffic management strategies. Also, a cost–benefit analysis of using microsimulation models in conjunction with tabletop exercises for these types of events was explored. The project was made possible by funding from the New York State Department of Transportation and the Federal Highway Administration.

Modelling passengers, buses and stops in traffic microsimulation: review and extensions

AbstractIn the last decade, significant research efforts and technology have been dedicated to the development of microsimulation tools for a better representation of traffic systems. As a result, several commercial packages appeared and they are used nowadays in the detailed modelling of different transportation systems and operations for specific project evaluations and local designs, mostly within the urban context. After reviewing the specialized literature, we realized that most of these microsimulation tools are oriented to the movement of cars, leaving the public transportation systems as a complement, just for a realistic representation of the transportation system as a whole, but always oriented to simulate cars. In this paper, the objective is to provide guidelines on how to incorporate the necessary entities and components for a proper simulation of public transport systems in a microsimulation environment. Thus, the different approaches to simulate transit systems at a microlevel are discussed, highlighting the necessity of including stops, passengers and transit vehicles explicitly as entities within the microsimulation environment, for modelling transfer operations, control strategies, etc. Several examples are then provided to quantify the impact of such representations, for different cases and potential simulation platforms. Copyright © 2010 John Wiley & Sons, Ltd.

Microscopic simulation of transit operations: policy studies with the MISTRANSIT application programming interface

Microscopic traffic simulators are the most advanced tools for representing the movement of vehicles on a transport network. However, the energy spent in traffic microsimulation has been mainly oriented to cars. Little interest has been devoted to more sophisticated models for simulating transit systems. Commercial software has some options to incorporate the operation of transit vehicles, but they are insufficient to properly consider a real public transport system. This paper develops an Application Programming Interface, called MIcroscopic Simulation of TRANSIT (MISTRANSIT), using the commercial microsimulator PARAllel MICroscopic Simulation. MISTRANSIT makes advances in three ways: public transport vehicles can have new characteristics; passengers are incorporated and traced as individual objects; and specific models represent the interaction between passengers and vehicles at stops. This paper presents the modelling approach as well as various experiments to illustrate the feasibility of MISTRANSIT for studying policy operations of transit systems.

Traffic signal optimization in "la almozara" district in saragossa under congestion conditions, using genetic algorithms, traffic microsimulation, and cluster computing

Urban traffic congestion is a pandemic illness affecting many cities around the world. We have developed and tested a new model for traffic signal optimization based on the combination of three key techniques: 1) genetic algorithms (GAs) for the optimization task; 2) cellular-automata-based microsimulators for evaluating every possible solution for traffic-light programming times; and 3) a Beowulf Cluster, which is a multiple-instruction-multiple-data (MIMD) multicomputer of excellent price/performance ratio. This paper presents the results of applying this architecture to a large-scale real-world test case in a congestion situation, using four different variables as fitness function of the GA. We have simulated a set of congested scenarios for ¿La Almozara¿ in Saragossa, Spain. Our results in this extreme case are encouraging: As we increase the incoming volume of vehicles entering the traffic network - from 36 up to 3600 vehicles per hour - we get better performance from our architecture. Finally, we present new research directions in this area.

Signal Priority near Major Bus Terminal

Near major bus terminals, multiple bus arrivals per signal cycle and a convergence of buses from conflicting directions can make it impractical to apply signal priority logic that attempts to interrupt the signal cycle for each bus. This research explores signal control logic for reducing bus delay around a major bus terminal in Boston, Massachusetts, where the busiest intersections see almost four buses per signal cycle. With a traffic microsimulation to model a succession of signal priority tactics, a reduction in bus delay of 22 s per intersection was obtained, with no significant impact on general traffic. The general strategy was to provide buses with green waves, so that they are stopped at most once, coupled with strategies to minimize initial delay. The greatest delay reduction came from passive priority treatments: changing phase sequence, splits, and offsets to favor bus movements. Green extension and green insertion were found to be effective for reducing initial delay and for providing dynamic coordination. Dynamic phase rotation, from lagging to leading left, proved less effective. Cycle-constrained free actuation, in which an intersection has a fixed cycle length within which two phases can alternate freely, provided flexibility for effective application of early green and green extension at one intersection with excess capacity. Emphasis is given to the approach of providing aggressive priority with compensation for interrupted phases, highlighting the compensation mechanism afforded by actuated control with snappy settings and long maximum greens.

Improving the Accuracy of IVC Simulation Using Crowd-sourced Geodata

We discuss the use of crowd-sourced geodata in simulative evaluations of Inter-Vehicle Communication (IVC) protocol designs. Typically, network simulation tools, which have been improved over decades of network research, are used for evaluating communication systems. In the area of IVC, however, additional challenges have to be met. Most important, the mobility of vehicles in network simulation needs to be represented accurately, e.g., using road traffic microsimulation techniques. These can be integrated with network simulation tools in order to provide a holistic view on the overall system performance. Obviously, the quality of these approaches inherently depends on the quality of provided map data. The OpenStreetMap project provides a community-maintained repository under an open license model. The available crowd-sourced geodata not only consists of road topology data but also includes fine-grained details such as traffic lights, speed limits, and even information about buildings, which represent obstacles for wireless communication. Using our Veins simulation framework, we show that this data increases the accuracy of IVC simulation.

Influence of coordinated traffic lights parameters on roadside pollutant concentrations

The paper examines the effects of coordinated traffic lights on CO and C 6H 6 roadside concentrations in an urban area of Palermo in Southern Italy. Traffic loop detectors and one pollution-monitoring are used to collect data for use in DRACULA traffic microsimulator software. CO and C 6H 6 roadside concentrations associated with varying cycle and offset times of the coordinated traffic lights are estimated using a neural network. Two functions were set up describing the relations of pollutant concentrations in term of cycle and offset time.

Traffic Parameters Estimation to Predict Road Side Pollutant Concentrations using Neural Networks

The analysis aims to evaluate which is the most important among traffic parameters (flows, queues length, occupancy degree, and travel time) to forecast CO and C6H6 concentrations. The study area was identified by Notarbartolo Road and bounded by Liberta Street and Sciuti Street in the urban area of Palermo in Southern Italy. In this area, various loop detectors and one pollution-monitoring site were located. Traffic data related to the pollution-monitoring site immediately near the road link were estimated by Simulation of Urban MObility (SUMO) traffic microsimulator software using as input the flows measured by loop detectors on other links of road network. Traffic and weather data were used as input variables to predict pollutant concentrations by using neural networks. Finally, after a sensitivity analysis, it was showed that queues length were the mostly correlated traffic parameters to pollutant concentrations.

Pedestrian and Vehicle Flow Calibration in Multimodal Traffic Microsimulation

This paper provides a method for including pedestrians in a vehicle microsimulation model, specifically the VISSIM model. VISSIM provides a default mechanism for simulating pedestrian movements; however, this does not adequately replicate pedestrian behavior. We instead define pedestrians as vehicles and calibrate various parameters within VISSIM so that pedestrian behavior is calibrated with pedestrian speed-flow models. We validate and refine these parameters using a real traffic network with high levels of pedestrian traffic crossing at signalized junctions. This work demonstrates the feasibility of modeling vehicle-pedestrian interactions in a realistic manner and provides analysts with a tool for evaluating policies that affect both vehicle and pedestrian flows.

Generating artificial popullations for traffic microsimulation

Travel demand is derived from people's participation in daily activities scattered in time and space. Traffic microsimulation starts by generating individuals to participate in activities. In this paper, we propose a framework called Artificial Population Systems (APS) in order to automatically generate artificial populations for traffic microsimulation. Different from the conventional approach using empirical data to generate synthetic populations for the base year, our APS framework can generate artificial populations which evolve with time and space. So, with artificial populations, we will get more reasonable traffic demand forecast and analytical results in long term traffic microsimulation.

Scheduling Buses to Take Advantage of Transit Signal Priority

Transit signal priority can improve bus operations when it is applied to a route without making any changes to its route design or management; however, benefits can be greater if service design and management policies are purposely altered to take advantage of transit signal priority. Service design issues include generating carefully constructed schedules for use with conditional priority and deciding whether to locate stops on the near side or far side of intersections. Management issues include using conditional priority as a means to give priority only to late buses and deciding whether to hold buses at bus stops until a scheduled departure time, in case conditional priority itself does not offer the desired level of operational control. An optimal level of aggressiveness in the running time schedule is sought as a balance between mean running time with and without priority, assuming that priority will be conditional. With a more aggressive schedule, buses will be late and therefore will request (and get) priority more often; however, a more aggressive schedule also offers less slack to compensate for random delays. Analysis uses both a spreadsheet-based simulation model and a traffic microsimulation model that account for random delays at dispatch and at traffic signals, the effect of crowding on dwell time, and choice of priority and operational control tactics. It is found that optimal performance uses conditional priority and holding, but with an aggressive schedule, leading to substantial reductions in mean running time, standard deviation of running time, headway irregularity, and crowding.

Adding Mode Choice to Multiagent Transport Simulation

It had been shown previously that so-called agent-based traffic micro-simulations could be used for dynamic traffic assignment, that is, iterative route adjustment, until either a Nash equilibrium or some steady state distribution between alternatives had been found. It was also shown that the same approach could be extended to (departure) time adjustment; that is, time adjustment and route adjustment could exist in the same iterative approach. In this paper it is shown that the approach can be extended to mode choice by forcing every synthetic traveler to consider every available mode. The implementation is verified with a test case for which an approximate solution can be analytically derived and for which it is shown that simulation and theory are consistent. It is then applied to a large-scale real-world example, the metropolitan Zurich, Switzerland, area, with about 1 million inhabitants. For this example, it is shown that the adaptive scheme, albeit seemingly simple, can outperform a more traditional approach that first computes mode choice on the basis of aggregate data and then runs the assignment for car traffic only. Sensitivity tests show that the model reacts in meaningful ways, in particular concerning the interaction between the time structure of activities and mode choice.