A station box is a term in the construction industry: It describes a box-like underground structure for a transportation system, for example a metro or tube station. When building such a station, a chamber as large as the station structure is dug into the ground into which the station is built. When the construction is complete, this station box is covered again up to the street level.
The lowest level - where the platform for the arriving and departing trains are - is called the Platform Level. Often another underground level - the Concourse Level is placed on top of the platform level: This level would contain ticket vending machines or/and offices, the station master room, technical rooms, stores and shops, and other station facilities.
When building an underground transportation system using tunnel boring machines (TBM), the station box can be built before or after the TBM goes through that area. If the station box is created after the TBM has passed through, the tunnel built by the TBM would be replaced by the station box. If the station box is built before the TBM passes through, the TBM would drill through the side of the station box, would have to be moved to the other side of the station box where it would restart the tunnel boring process.