Patent ID: 8392103

Claim:
A method for operating a train on a train track according to a smaller-size database that captures the geometry of the train track, the method comprising: obtaining a set of geo-locations from a survey of the train track, wherein each geo-location is a point on the centerline of the train track, and wherein a first database comprises the obtained set of centerline geo-locations; converting the centerline geo-locations from latitude/longitude/altitude to a set of points expressed in three-dimensional Earth-Centered Earth-Fixed Cartesian coordinates; generating, by a data-processing system, based on the three-dimensional coordinates of the set of points, a piecewise polynomial spline that is defined in terms of a proper subset of the set of points; populating, by the data-processing system, a first data structure in a second database, wherein the first data structure stores for each point P in the subset of the piecewise polynomial spline: (i) the three-dimensional Earth-Centered Earth-Fixed Cartesian coordinates of the point P, (ii) an estimate of the heading of the train track at the point P, (iii) an estimate of the grade of the train track at the point P, and (iv) an estimate of the curvature of the train track at the point P; populating, by the data-processing system, a second data structure in the second database, wherein the second data structure stores for each of a non-empty set of features along the train track: (i) an indicium of a point in the subset of the piecewise polynomial spline, and (ii) an offset from the point to the feature; wherein the second database comprises a smaller quantity of data than the first database; and operating the train on the train track according to the second database.