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TrafficCast International's fusion process
includes model integration, information filtering,
and data normalization. As stated before,
TrafficCast International uses a combination of
statistical model, heuristic model, simulation
model, and Dynamic Traffic Assignment model. To
use which model or a combination of models is
dependent on the application needs and the
availability of data. In some cases, the output of
statistical model and/or heuristic model is used
as the initial input to simulation model and/or
DTA model to generate dynamic traffic information
and forecasting to support a variety of
applications.
TrafficCast International uses a rigorous
Quality Assurance and Quality Control (QA/QC)
mechanism to calibrate and verify the model output
to ensure the prediction accuracy. For instance,
by using fuzzy logic TrafficCast International
develops an online calibration procedure to
compare the predictive speed generated by model to
the speed collected by DOT speed sensors in
real-time to verify its prediction accuracy. If
this discrepancy is over a pre-set threshold, the
model ¡°learns¡± the mistake and adjusts itself
internally to improve its prediction. This process
is implemented repeatedly very 5 minutes for
markets where real-time speed is available. For
markets without speed sensors but have traffic
cameras, a web-based operator interface allows
operators to provide input based on what he/she
sees on the camera for model to change its
prediction behavior.
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