58) What is the name of scaffold, if it is formed with steel in special types of couplings and frames?

59) Which scaffold is suitable, if proper hard ground is not available for standards to rest?

60) What is the name of timber piece used to give rigidity to frame work in timbering?

61) What is the approximate depth of vertical sheeting adopted in timbering in soft ground?

62) What is the minimum period for the removal of props to beams and arches for a span of 6m in centrering / form work?