2013 Session: 398

• Evaluation of VISSIM and FREEVAL to Assess an Oversaturated Freeway Weaving Segment
  Abstract: The HCM 2010 does not provide a methodology to assess Level-of-Service (LOS), density, and space mean speed for oversaturated freeway weaving segments. In its supplemental chapters it suggests use of either analytical tool called FREeway EVALuation (FREEVAL) or a commercial microsimulation software. This study evaluates ability of such tools to realistically generate density and speed on oversaturated freeway weaving segments. The study utilizes NGSIM data for an oversaturated weaving segment on a US 101 Hollywood Freeway in California to populate FREEVAL and VISSIM (a representative of commercial microsimulation software) models. Both models are calibrated, to the best possible extent, to replicate field data for the first two 15-minute intervals from NGSIM data set. The last 15-minute interval is used to assess ability of these tools to reproduce performance measures on an oversaturated freeway segment. Results show that FREEVAL is not able to accurately estimate both speed and density of oversaturated freeway weaving segment. On the other hand, the results showed that VISSIM microsimulation model can be successfully calibrated to replicate speed and density from the field but only after introducing a speed reduction areas to emulate effects of queue propagation from downstream (out of model) links.
  Authors: Jolovic, Dusan; Stevanovic, Aleksandar
  Authors: Jolovic, Dusan; Stevanovic, Aleksandar
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-0484
• Sensitivity Analysis of VISSIM Driver Behavior Parameters on Safety of Simulated Vehicles and Their Interaction with Operations of Simulated Traffic
  Abstract: Microscopic traffic simulation models, VISSIM in particular, have been continuously used in assessing operational performance of traffic networks. Recently, their application for safety assessment has also been mounting. However, modelers are practically left without any guidance on the impact of VISSIM parameter values for car-following and lane-changing models on safety of the simulated vehicles (aggressiveness or defensiveness) and their interaction with the operational aspect of the simulated traffic. This paper provides quantitative evaluation on the impact of these parameters by means of a sensitivity analysis on total of 21 driver behavior parameters of VISSIM (10 for car-following and 11 for lane-changing models). For the safety analysis, Surrogate Safety Assessment Model (SSAM) is used to detect the change in frequency of the simulated vehicle conflicts and the change in travel time is used to evaluate the impact on operational aspect of the simulation. The results identified that the most influential parameters for safety of the simulated vehicles are CC1 (Headway Time), CC2 (Following Variation), CC3 (Threshold for Entering ‘Following’) as well as CC4 and CC5 (‘Following’ Threshold) for the car-following model; ‘Safety distance reduction factor’ for free lane-changing model; ‘Lane changing position’ and ‘Maximum deceleration of trailing vehicles’ for necessary lane-changing model. The majority of these parameters are also found to interact with travel time of the simulation. It is concluded that parameter values have a significant impact on aggressiveness or defensiveness of the simulated vehicles and accordingly impact the safety and operations of the simulated traffic. Thus, common calibration process requires cautious examination on the way the simulated vehicles behave and it is important to balance the value of parameters that improve network performance but deteriorate the safety of the simulated vehicles or vice versa.
  Authors: Habtemichael, Filmon; Picado-Santos, Luis Guilherme
  Authors: Habtemichael, Filmon; Picado-Santos, Luis Guilherme
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-2767
• Deterministic Model Validation with New Approach to Fundamental Diagrams of METANET Model
  Abstract: This paper is concerned with the macroscopic traffic flow model validation problem. An evolutionary algorithm is used to validate the METANET macroscopic road network simulator solving a least squares optimisation problem. The implementation approach followed is that of a black box, i.e. the optimisation algorithm and METANET are completly decoupled. The evaluation of the merit function for each member of the population is done by a direct call to METANET’s executable using a properly formatted input file. This allows for the same software tool to be applied to different sites, and models, with little changeover and setup effort. An additional innovation of the proposed approach is that through an extension of the objective function it is possible to dynamically ascertain where fundamental diagrams should change in the model and for how many of them should be used for a particular site. Three separate UK sites are considered here. Each has its own unique congestion pattern. The model validation process is split into two parts, the model calibration and the model verification. The procedure successfully calibrates all models for which the algorithm is run and a model is obtained that is verified over the entire month.
  Authors: Poole, Adam James; Kotsialos, Apostolos
  Authors: Poole, Adam James; Kotsialos, Apostolos
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-4046
• Enhancing and Calibrating Rakha-Pasumarthy-Adjerid Car-Following Model Using Naturalistic Driving Data
  Abstract: The research presented in this paper analyzes the simplified behavioral vehicle longitudinal motion model, currently implemented in the INTEGRATION software, known as the Rakha-Pasumarthy-Adjerid (RPA) model. The model utilizes a steady-state formulation along with two constraints, namely: acceleration and collision avoidance. An analysis of the model using the naturalistic driving data identified a deficiency in the model formulation, in that it predicts more conservative driving behavior compared to naturalistic driving. Much of the error in simulated car-following behavior occurs when a car-following event is initiated at a spacing that is often much shorter than is desired. The observed behavior is that, rather than the following vehicle decelerating aggressively, the following vehicle coasts until the desired headway/spacing is achieved. Consequently, the model is enhanced to reflect this empirically observed behavior. Finally, a quantitative and qualitative evaluation of the original and proposed model formulations demonstrates that the proposed modification significantly decreases the modeling error and produces car-following behavior that is consistent with empirically observed driver behavior.
  Authors: Sangster, John; Rakha, Hesham
  Authors: Sangster, John; Rakha, Hesham
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-1518
  Practice-Ready: Yes
• Evaluation and Improvement of Consistency of Hybrid and Multiresolution Traffic Simulation Models
  Abstract: In recent years, hybrid traffic models, which combine aspects of models with different time resolutions have been developed. These models, however, have additional consistency constraints, when compared with non-hybrid models, such as the need to maintain consistency across their components models. This consistency requirement takes two forms, model-based consistency, i.e. whether the model outputs and measures of effectiveness match under specific conditions; and process-based consistency, i.e. whether the models maintain consistency as demands or roadway conditions change. This paper is intended to provide insight into statistical measures that can be used to evaluate both kinds of consistency, and to demonstrate a process that can be used to increase the consistency of models.
  Authors: Tokishi, James; Chiu, Yi-Chang
  Authors: Tokishi, James; Chiu, Yi-Chang
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-5241
  Practice-Ready: Yes
• Multistep Approach for Global Sensitivity Analysis of Complex Traffic Simulation Models: Application to MITSIM Model
  Abstract: In this work a multi-step approach for model sensitivity analysis has been discussed and applied to the MTISIM traffic simulation model. Throughout the paper it is argued that the application of sensitivity analysis is crucial for a true comprehension and the correct use of traffic simulation models, but it is also acknowledged that the main obstacle towards an extensive use of the most sophisticated techniques is jeopardized but the high number of model runs usually required, especially in the case of models with a high number of model parameters.For this reason we have tested the possibility to perform a number of preliminary analyses by grouping model parameters on the basis of possible common features (in particular grouping all the parameters pertaining to the same sub-models) and, then, to use sensitivity analysis to discover which groups of parameters accounts for the highest share of the outputs’ variance. At the end of these preliminary steps a final sensitivity analysis on the parameters pertaining to the most influential groups can be performed to individuate the most important among them.The proposed methodology has been applied to the MITSIM model (101 model parameters) and has allowed uncovering the role played by the different parameters and by the model stochasticity with 80% fewer model evaluations.
  Authors: Ciuffo, Biagio Filippo; Lima Azevedo, Carlos
  Authors: Ciuffo, Biagio Filippo; Lima Azevedo, Carlos
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-3726
  Practice-Ready: Yes
• Efficient Methodology for Calibrating Traffic Flow Models Based on Bisection Analysis
  Abstract: In order to support a roadway surveillance system for drivers' aggressions under different road conditions, the research demonstrated in this paper focuses on developing a heuristic methodology on calibrating traffic flow models in real-time. Objectives for this development are high accuracy, high efficiency and high robustness. Techniques like data aggregation and bisection analysis are applied in our approach to ensure achieving these goals and further requirements. Two traffic flow simulation models, Longitudinal Control Model (LCM) and Newell's Model are calibrated by applying our approach using traffic data collected at Georgia 400 highway in July, 2003. Running time for calibrating these two models are less than a second, respectively, and eight different field data samples are opted for experiments to prove this method's accuracy and robustness.
  Authors: Jia, Chaoqun; Ni, Daiheng
  Authors: Jia, Chaoqun; Ni, Daiheng
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-3932
  Practice-Ready: Yes
• Calibration of Traffic Flow Models Under Adverse Weather and Application in Mesoscopic Network Simulation Procedures
  Abstract: The weather-sensitive Traffic Estimation and Prediction System (TrEPS) aims to accurately estimate and predict traffic state under inclement weather conditions. Successful application of weather-sensitive TrEPS requires detailed calibration of weather effects on traffic flow model. In this paper, systematic procedures of the entire calibration process are developed, from data collection, through model parameter estimation, to model validation. Following the procedures, dual-regime modified Greenshields model and weather adjustment factors are calibrated for four metropolitan areas across the United States (Irvine, Chicago, Salt Lake City, and Baltimore), using freeway loop detector traffic data and weather data obtained from Automated Surface Observing System (ASOS) stations. It is observed that visibility and precipitation (rain/snow) intensity have significant impacts on the value of some traffic flow model parameters, such as free flow speed and maximum flow rate; while these impacts can be included in weather adjustment factors. The calibrated models are fed as input into weather integrated dynamic traffic assignment simulation system. The results show that the calibrated models are capable of capturing the weather effects on traffic flow more realistically than TrEPS without weather integration
  Authors: Hou, Tian; Mahmassani, Hani S.; Alfelor, Roemer; Kim, Jiwon; Saberi, Meead
  Authors: Hou, Tian; Mahmassani, Hani S.; Alfelor, Roemer; Kim, Jiwon; Saberi, Meead
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-5359
  Practice-Ready: Yes
• Enhancing and Calibrating Rakha-Pasumarthy-Adjerid Car-Following Model Using Naturalistic Driving Data
  Authors: Sangster, John
  Authors: Sangster, John
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-1518
• Deterministic Model Validation with New Approach to Fundamental Diagrams of METANET Model
  Authors: Poole, Adam
  Authors: Poole, Adam
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-4046
• Evaluation of VISSIM and FREEVAL to Assess an Oversaturated Freeway Weaving Segment
  Authors: Stevanovic, Aleksandar
  Authors: Stevanovic, Aleksandar
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 398
  Paper Number: 13-0484