Constructing Road Underpass below ongoing continuous railway track is one of the most difficult construction having higher risks as the construction is to be done even though the train is moving on the tracks.
Box Pushing technology is used to construct such under passes. The term "Box Pushing" is similar to the Match Box fundamentals. A concrete box is created outside the underpass in the dug out area and slowly pushed using hydraulics and pistons. The soil in the front part of the concrete box is dug slowly so that the mud/soil doesn't fall immediately, which may cause a disaster as the rail is already in running on the tracks above.