Microscopic Traffic Simulation Program Research Articles

Assessing the Influence of Adverse Weather on Traffic Flow Characteristics Using a Driving Simulator and VISSIM

The occurrence of adverse weather exacerbates traffic flow conditions, often leading to severe traffic congestions. Many studies have been conducted based on field-collected data to obtain the effects of weather on traffic flow characteristics. However, there is a limitation for filed data-based studies, in that weather conditions and traffic conditions are both noncontrollable and nonrepeatable, making it difficult to comprehensively assess the influence of weather conditions, especially the rare extreme weather conditions, on traffic flow characteristics. This paper proposes to assess these effects with the combination of driving simulator and traffic simulation. A driving simulator can collect driving behavior by conducting weather-related driving simulation experiments, while a microscopic traffic simulation program can evaluate the changes in traffic flow characteristics by inputting driving behavior parameters coming from the driving simulator. The proposed method can overcome the limitation of the field data-based approach. In this paper, the structure of the assessment platform is introduced at first. Then a verification experiment is conducted to measure the influences of adverse weather conditions on traffic flow characteristics. The verification experiment results show that the influences of adverse weather on traffic flow characteristics have consistent tendencies with outcomes from previous research and demonstrate that the method is practicable for the analysis of the influence of weather on traffic flow characteristics. This paper provides a practical way to analyze the influence of weather on traffic flow from driving behavior’s point of view.

Effects of the prevision relative velocity on traffic dynamics in the ACC strategy

This paper focuses on exploring the effects of the prevision relative velocity on the dynamics characteristic of the simulated traffic flow in the ACC strategy. Firstly, an improved car-following considering the prevision relative velocity is developed for numerical simulations. Secondly, an adaptive neural-fuzzy inference system is trained and employed to predict the relative velocity. Thirdly, a microscopic traffic simulation program is created to analyze the traffic flow evolution process, further to explore the effects of the prevision relative velocity on the dynamics characteristic. The results show that considering the prevision relative velocity in designing the ACC control strategy can significantly affect the dynamics characteristic of the simulated traffic flow, which can improve the traffic flow stability in the ITS environment.

Effects of vehicle gap changes on fuel economy and emission performance of the traffic flow in the ACC strategy.

This paper focuses on the effects of vehicle gap changes on fuel and emission performance of the simulated traffic flow in the adaptive cruise control (ACC) strategy. Firstly, the close correlation of vehicle gap changes and the host car's behaviors was explored with the measured car-following data. Secondly, the correlation between the host car's velocity and vehicle gap changes with different memory steps was also explored to develop the nth car’s optimal velocity function. Thirdly, a microscopic traffic simulation program was created for analyzing the traffic flow evolution process and approximately estimating the fuel consumptions and exhaust emissions. As a result, it was seen that vehicle gap changes with memory significantly affect fuel economy and emission performance of the simulated traffic flow in the ACC strategy, which can result in low fuel consumptions and exhaust emissions. This study is an incremental step forward for designing the control strategy of the ACC system.

Sustainable Highway Operations: High Occupancy Lane and Movable Lane

Two managed lane schemes, the high occupancy vehicle lane (HOV) and the movable lane operations, were analyzed to determine their suitability as a sustainable highway operation. VISSIM, a microscopic traffic simulation program, was used for this study, and parameters representing driver behavior in the car following model were calibrated according to a macroscopic speed and flow relationship based on measured data. The analysis results showed that bus travel speed was improved in the HOV operation, while movable lane operation also considerably improved car travel speed.

Slip ramp design for dedicated truck lanes using microscopic traffic simulation

Dedicated Truck Lanes (DTL) are planned in the United States along freight-intensive corridors, namely Corridors of the Future. In rural areas along these corridors, slip ramps will provide access to heavy vehicles between the truck-only lanes (TOL) and the general purpose lanes (GPL) to subsequently enter and exit the facility using an interchange. This paper examines the distance between the slip ramp and an interchange required by heavy vehicles to enter and exit the facility using a microscopic traffic simulation program, VISSIM. This distance consists of a merge, link, and a diverge segment. The procedure for determining this distance included (a) examining the acceleration/deceleration characteristics of vehicles, (b) specifying the parameters in VISSIM based on vehicle characteristics and driver behavior, (c) coding and simulating the traffic on DTL in VISSIM, (d) analyzing the speed–flow relation for passenger and heavy vehicles for the various lengths of merge, link, and diverge segments on the GPL, slip ramps, merge, and diverge segments of TOL, and (e) determining the slip ramp distance to (and from) the interchange for level, upgrade, and downgrade. To determine the different segment lengths, a rotatable central composite design (RCCD) was used to generate a reasonable number of cases required for simulation. Simulation of peak period traffic on level grades indicated that the lengths of segments were directly proportional to the average speed of heavy vehicles. As the slip ramp distance from and to the interchange depended on the lane change behavior of drivers, a sensitivity analysis was performed for the safety distance reduction factor (SDRF), the main lane change parameter in VISSIM. This paper provides state departments of transportation with design recommendations for slip ramp design for the Corridors of the Future project. The paper also provides a unique application of microscopic simulation to highway facility design.

Microscopic traffic behaviour modelling and simulation for lane-blocking arterial incidents

Incident-induced driver behaviour modelling is essential to analyse non-recurrent traffic congestion problems. However, such research is inadequate in such areas as traffic flow prediction, traffic simulation and incident management. This article presents microscopic lane traffic models to characterise incident-induced driver behaviour including car following and lane changing conducted under conditions of lane-blocking arterial incidents. To demonstrate the validity of the proposed models, a specific microscopic traffic simulation program embedded with the proposed incident-induced lane traffic behaviour models is tested by comparing simulation data with video-based incident data collected from five incident events. Preliminary test results indicate that the proposed microscopic traffic behaviour models permit not only reproducing incident-induced traffic behaviour but also characterising incident effects on lane traffic phenomena.

Optimizing Minimum and Maximum Green Time Settings for Traffic Actuated Control at Isolated Intersections

Optimization of signal control at isolated intersections has been an important research focus in traffic engineering over the past few years. Due to its flexibility and practicality, fully actuated control has been extensively deployed. In the conventional actuated control scheme, two important parameters, i.e., minimum and maximum green times, are arbitrarily prespecified, although it is widely recognized that they can significantly impact system operations. Previous studies have concentrated on computing these parameters using deterministic models. Due to the stochastic features of traffic arrival, such statically designated green time boundaries cannot sufficiently handle various traffic demands. To solve this problem, a stochastic model is established to dynamically optimize the minimum and maximum green times using real-time queue lengths and traffic arrival characteristics for each phase. Multiple criteria are fused and exploited as control objectives, such as avoiding cycle failures, minimizing control delays, and maximizing total traffic throughputs. Performance of the proposed algorithms is examined using a microscopic traffic simulation program, i.e., VISSIM 4.30, under various scenarios. The results show that the control system operated by the proposed algorithm produces promising improvements in system operation efficiency and fairness under various traffic demands.

Application of Distributed Traffic Simulation for Passing Behavior Study

The suitability of a prototype distributed traffic simulation for passing behavior studies was examined. The prototype was based on the High Level Architecture and was designed to combine the microscopic traffic simulation program VISSIM with the driving simulator DriveSafety. Specifically developed for the passing behavior application, the prototype was capable of modeling traffic on two-lane, two-way rural roads. Vehicle information was transferred from the VISSIM federate to the Drive-Safety federate to control the creation of vehicles and their speeds. The passing experiment had a repeated-measure, factorial design with two levels of impeding vehicle length and two levels of impeding vehicle speed. Twenty-four test drivers, each with at least 5 years of driving experience, successfully completed a pass under each experimental condition. The passing time and passing distance were observed to be significantly greater when the impeding vehicle was a truck than when it was a passenger car. The mean distance traveled in the left lane and the mean end gap distance were found to be approximately double those reported previously. Likewise, the mean start gap distance was found to be triple that reported previously. These differences were likely due to drivers’ propensities to underestimate distances in simulated environments. This study methodology had the advantage of capturing detailed driver information, but concerns about the validity of the methodology and the transferability of the results to the real world warrant further examination.

Alternative Methods to Increase the Effectiveness of Freeway Contraflow Evacuation

The city of New Orleans is among the most vulnerable cities in the world to the threat of hurricanes. To protect its population from these storms, officials in Louisiana have joined a growing number of states that are planning to use contraflow freeway operations to expedite the evacuation of threatened areas. Although contraflow is widely regarded as a major advance in evacuation planning and response, no one really knows how well, or even if, it will work. Research was undertaken to improve the understanding of traffic conditions on contraflow freeway segments during an evacuation. The CORSIM microscopic traffic-simulation program was used to model the freeway configuration that will be used to evacuate New Orleans as well as two alternative scenarios for this same segment. The results showed that the currently proposed configuration might result in an underutilization of the contraflow segment, thus significantly limiting the number of evacuees who can get out of the city. The study also showed how the effectiveness of the New Orleans contraflow segment might be significantly improved with some simple and inexpensive modifications to the existing plan. Most important, the results of the research underscore the critical nature of proper planning and design of contraflow entry points and how they are often overlooked for both emergency and nonemergency conditions.

Adaptive Signal Control System with Online Performance Measure for a Single Intersection

An adaptive signal control system with an online signal performance measure is introduced. Unlike conventional signal control systems, the proposed method uses real-time delay estimation and an online signal timing update algorithm. As a signal performance measure, intersection delay for each phase is measured in real-time via an advanced surveillance system that reidentifies individual vehicles at upstream and downstream stations by using vehicle waveforms obtained from advanced inductive loop detectors. In each cycle, the signal timing plan is optimized based on the delay estimated from the vehicle reidentification technology. The main thrust of the algorithm is the online control capability utilizing direct intersection delay measures. A description of the overall control system architecture and the optimization algorithm is addressed. Performance of the proposed system is evaluated with a high-performance microscopic traffic simulation program, Paramics, and the preliminary results prove the promising properties of the proposed system.

Road User Cost Models for Network-Level Pavement Management

Life-cycle cost analysis (LCCA) of pavements is a process for evaluating total economic worth of a usable project segment by analyzing initial costs and discounted future costs, such as those for maintenance, reconstruction, rehabilitation, and resurfacing. One of the most important ingredients in the LCCA process, at either a network level or a project level, is the determination of road user cost (RUC) during maintenance and rehabilitation operations. RUC models are also important in contracting strategies, which take into account time for a project to be completed for award and payment. Methods used to date to determine RUC are exclusively analytical in nature. Microscopic estimates of traffic are used to determine RUC. CORSIM, a microscopic traffic simulation program developed by FHWA, was used for this research. Models for additional travel time, added fuel consumption, and RUC for standard two-to-one lane closure scenarios are presented.

Traffic Simulation with Consideration of Driver Models, Theory and Examples

SUMMARY In the last five years the IKA (Institut für Kraftfahrwesen Aachen) and BMW created the microscopic traffic simulation program PELOPS. It simulates the traffic flow on motorways with a specific view on vehicle affairs. One application for PELOPS was the assessment of ACC (Adaptive Cruise Control) systems inside the PROMETHEUS program. It was shown, that PELOPS is a powerful tool for the analysis of new technologies. A new research period will extend the use of ACC about the functionality in urban areas. This requires an extension of PELOPS about some specific models. With this extension it is possible, to analyse new traffic technologies for the individual vehicles or the infrastructure. In a first step, PELOPS is extended about functions for suburban areas. This effects mainly the modelling of the driver behaviour. The driver behaviour is related to the traffic situation. In contrast to the normal traffic flow on motorways, the driver has to stop and go in the suburban area, he has to control lower distances and he has to react on other vehicles on cross-roads. New concepts for these functions are included in PELOPS and calibrated by detailed traffic data from a video observation and floating car measurements in the surrounding of Aachen. Based on the traffic measurement near Aachen, different scenarios are simulated to improve the traffic flow and to relieve the environment. These scenarios include ACC systems, inter-vehicle-communication and intelligent traffic lights. The paper shows some information's about the simulation technic and the results from the described analysis.