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ALIGNMENT OF TUNNEL

GET FULL KNOWLEDGE WITH PRACTICAL APPROACH   ALIGNMENT OF TUNNEL  AND  GET KEY TO GRASP MATERIAL ALIGNMENT OF TUNNEL The work contain the alignment of tunnel of centre line on surface and tranfer it to tunnel and good levelling work on surface and inside the tunnel can be achieved. 1)First a preliminary  location survey is done followed by very precise resurvey of line 2)As tunnel excavation is carried out from each end face as also from several intermediate shaft faces,minute accuracy in survey of centre line is essential 3)When tunnel is short,ordinary engineer transit,properly handled gives close and satisfactory results 4)When tunnel is very long it is very necessary to have a tunnel transit and is fitted with striding level by which transverse axis can be made truly horizontal 5)Levelling work is carried on in the standard way except for fact,that where steep slopes are encountered extra care are taken 6) Horizontal distance are measured by  Stepping Inclined sights Transfering ce