Safe interaction of railway vehicles to track and its geometry is of paramount importance to the railroad industry. Railroads currently utilize track geometry cars to measure the geometry for comparison to safety limits. However, these limits are set for individual measures of track geometry such as gage, surface (or profile), alignment, cross-level, etc. and have been defined based on nominal vehicle characteristics. The track and vehicle do not act independently, however, and so it is more appropriate to analyze the vehicle/track interaction. Prediction of the vehicle dynamic response to existing track geometry can be used to locate potentially unsafe locations in track, based on a range of vehicle configurations and operating speeds. While this is currently done in an offline mode, it would be advantageous to achieve this on a track geometry car in real-time. A limited real-time dynamic simulation system was developed for just this purpose. The model was initially based on the track analyzer method developed by Volpe National Transportation Systems Center, but was significantly enhanced in order to provide accurate predictions over a wider variety of vehicle behavior, and in response to a wider variety of track geometry conditions. Responses predicted by the model, including the vehicle bounce, roll, and pitch, as well as vertical wheel/rail forces, are compared with established limitations on vehicle response in order to identify unsafe locations in track. Inputs to the model include the relevant physical parameters of the vehicle, the range of vehicle travelling speeds to be analyzed, and the dynamic response safety thresholds with which exceptions are located. Finally, the system was validated (by comparison with NUCARS predictions) and tested for its real-time capabilities.
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