Methods and apparatus for determining that a train has changed paths

This invention relates generally to locomotive motion and location determination, and more particularly to methods and apparatus for determining, to a high level of certainty, that a train has changed from one path to another. A path determination device is configured to receive measured heading and distance information; determine heading corrections, distance corrections, and residuals utilizing a Kalman filter assuming a selected, known path was taken; and to determine a probability that the selected, known path actually was taken utilizing the determined residuals. The additional information utilized by the Kalman filters provides a more robust measurement indication of whether a particular path is taken than mere measurements and correlations of path curvature.