Railway crossover engineering is complex because of the many stages in the construction process. These need to be modeled in the Finite Element calculation to obtain stresses, but also especially displacements and settlements which are in agreement with reality.
Starting from CAD data, the geometry of the building process is defined. The essential structural parts of this data need to be modeled in the FE model in such a way that the most important force carrying mechanisms are well covered, but irrelevant details are not used in the FE model to prevent excessive calculation times.
This example shows a 3D calculation of such a railway crossover. For more information please see the pdf file.
The example is courtesy of IBES-GmbH, Germany, http://www.ibes-gmbh.de.