Q. Potential advantages of segmental tunnelling when compared with hand-shield pipe-jacking?

In segmental tunnelling, jacks are installed at the shield so that itisn't necessary to install thrust wall at the jacking pit. This provides the opportunity for smaller size of pit because of the absence of thrust wall. Also as the jacking operation includes the jacking of small length of segmental liner plates and consequently smaller force would be required for pipe jacking when compared with traditional pipe jacking (jacks at jacking pits) where jacking force is needed  to overcome long lengths of pipe drives. Alternatively, the use of segmental tunnelling provides better control in alignment since the steering operation could be performed at the shield.