Whereas, construction forms of high piers are still not perfect enough and line shapes of piers and continuous rigid beams can only be controlled with the control method of common Bridges.

Contrast to these common SPC systems, it can not only detect the unnatural process behavior on line, but can also learn and identify these unnatural patterns on control charts at the same time.

Crossbar switching was carried out by a special circuit called a maker which provided common control of number entry and line selection for all calls.