Using the dynamic model as a starting point, TfL can take a coordinated approach to scheme evaluation, road works and traffic management. The idea is not only to consolidate existing models, with all the efficiency, consistency and cost reduction that this implies, but also to update the model and enrich simulation knowledge through enhanced time segments. Now owned by Siemens, Aimsun has a long working history with TfL and will provide the software and services for an integrated, multi-level platform for modelling the city’s transport. Find a library where document is available.At this week’s Traffex show in Birmingham, UK, Spain-based transportation software developer Aimsun unveiled a major new agreement with Transport for London (TfL) to convert the London One Model into the company’s Next traffic modeling software.Results confirmed the power of the proposed methodology and also made a more extensive application of sensitivity analysis techniques available for complex traffic simulation models. The proposed methodology was assessed by comparing the results of the application of variance-based sensitivity analysis techniques with the simulation model and with a metamodel estimated with 512 model runs for a variety of traffic scenarios and model outputs. Sobol sequences and Gaussian process metamodels were recognized as the appropriate choices. Among these issues are the importance of selecting a proper sampling strategy based on low-discrepancy random number sequences and the importance of selecting a class of metamodels able to reproduce the inputs–outputs relationship in a robust and reliable way. Important issues concerning metamodel estimation were investigated and commented on in the specific application to the AIMSUN model. For this reason, the possibility of performing a sensitivity analysis was tested not on a model but on its metamodel approximation.
The application of sensitivity analysis is crucial for the true comprehension and correct use of the traffic simulation model, although the main obstacle to an extensive use of the most sophisticated techniques is the high number of model runs such techniques usually require. This study adopted a metamodel-based technique for model sensitivity analysis and applied it to the AIMSUN mesoscopic model. Gaussian Process Metamodels for Sensitivity Analysis of Traffic Simulation Models: Case Study of AIMSUN Mesoscopic Model
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