Intermediate Jacking stations (IJS) are placed between the main jacking station and the end of the pipe being jacked on long jacking drives. The IJS includes a lead pipe - through which the pipe being jacked enters the IJS - a hydraulic ram system within a steel cylinder to push the pipe and a trailing pipe through which the pipe being jacked leaves the IJS.
The IJS is assembled on the surface and lowered into the path of the pipe through an access pit along the path of the pipe.
Intermediate jacking stations multiply the strength of the man jacking station's jacks over a distance. As the end of the pipe being jacked through the soil is pushed farther from the main jacking station, five factors work to limit the capability of the main jack:
- Friction between the pipe and the soil
- The soil's compression on the pipe
- The ability of the pipe to withstand the pressure of jacking over a distance
- Pipe diameter
- The geology of the soil along the pipe's planned path
Because the IJS places a ram close to the end of the pipe, it minimizes the stresses on the pipe being jacked through the soil and ensures the pipe follows the design pathway without disruption.