MULTITUDE

The main objective of the Action TU0903 is to develop, implement and promote the use of methods and procedures for supporting the use of traffic simulation models, especially regarding model calibration and validation, to ensure their proper use and the validity of the results and the decision made on them.

Secondary objectives are developed within the four themes listed below.

1. State of the art of traffic simulation practice and research

• To perform a survey regarding the use in the common practice of traffic simulation tools, especially covering issues of model calibration and validation against actual traffic data.

• To review data collection techniques and estimation methodologies for innovative traffic data, e.g. vehicle trajectory data;

• To review data reduction techniques for standard, i.e. commonly available traffic data e.g. point detector data;

• To review literature on estimation, calibration and validation of traffic flow models and corresponding methodologies including reference to the problem of estimating and refining travel demand matrices using traffic data.

2. Highway modelling

• To share and exchange already available datasets of advanced traffic data - especially vehicle trajectory datasets;

• To define features and minimal requirements of accuracy of vehicle trajectory data for use in design process and/or estimation of traffic flow models;

• To develop and implement filtering/estimation techniques for vehicle trajectory data, according to the stated requirements;

• To develop a general methodology for drawing inference about the impact of parameters on model outputs. The methodology will consider effects on different outputs/measurements, e.g. individual trajectories as well as counts at detectors;

• To understand the variability of parameters from traffic data due to road type, traffic conditions, weather conditions for the most widely used traffic flow models;

• To give a comprehensive statement of the problems of traffic model estimation and validation, also addressing the issues of parsimony, over-fitting and transferability;

• To develop and implement methodologies, suitable for deterministic as well as stochastic models, for estimating traffic model parameters from vehicle trajectory data and standard data;

• To verify the effects on model estimation of measurement errors in traffic data;

• To define methodologies for validation of purely highway models.

3. Network modelling

• To share and exchange already available datasets of standard traffic data also promoting the International Traffic Database (ITDb);

• To define features and minimal requirements of accuracy of standard traffic data for use in calibration and validation of traffic flow models in network applications;

• To develop and implement data reduction techniques for standard traffic data according to the stated requirements;

• To get a better understanding of the impacts of randomness on traffic simulation;

• To give a comprehensive statement of the problems of traffic flow model calibration and validation on network, also addressing the problem of refining travel demand matrices and route choices;

To develop methodology to set up a calibration process on networks; the calibration methodology will also address the issue of variability of parameters over the network with road type, traffic conditions, and weather conditions. Besides it will address the problem of refining travel demand matrices and route choices;

• To verify the effects on model calibration of measurement errors in traffic data;

• To define methodologies for validation of network traffic models.

4. Synthesis, dissemination and training

• To draw general principles and unified conclusions at highway and network level; the whole methodological framework of traffic model estimation, calibration and validation will be covered.

• To prepare common guidelines for setting up simulation studies; the guidelines will encompass methodological and practical aspects from the choice of the most appropriate traffic tool for the specific application to that of the traffic data, to the setting up and the execution of the calibration and validation processes, to the quantitative comparisons of traffic scenarios and design alternatives;

• To define future needs for data gathering and processing;

• To define future needs for model and software development;

• To provide training for end users in setting up simulation studies; to this aim one open workshop, and one training school for early stage-researchers and practitioners will be organized.