With the progress of jacking, the front unit with shield penetrates into the embankment and there after excavation within the shield is done either manually or mechanically and the excavated stuff is transported outside the working area.After the first segment advances to the end of the thrust bed, the second segment is brought in alignment of the front Box & intermediate jacking space is lift between the two. The progress of pushing is kept continuous and the system of side shifting of remaining box segments from Auxiliary bed and bring in pushing alignment is adopted till total length is pushed.

The entire Box Pushing system is matter of proper selection of Hydraulic equipments, as tremendous driving force is required for pushing of medium to large size of Boxes. So for this, Number of Jack units are provided in series for distribution of pushing load evenly on the face of the concrete, and all Jacks are operated simultaneously with a common power pack, which supplies uniform flow of pressure through network of Hydraulic pipes of required pressure capacity, commencing from front unit to rear unit. Jacking force is applied in sequence. This way pushing cycles are repeated till total pushing is completed.