Because of limited underground space due to jamming structures, it is required to construct tunnels in unprecedentedly deep underground or in shallow underground with the accurate shield control technique. Thus, it is necessary to adopt a technique based on a theoretical model in place of the conventional technique to construct tunnels. To verify the validity of the theoretical model, precise data on shield behaviors were obtained from two tunneling sites of rail way by a newly developed survey system. This paper reports to measuring results and factors of shield behavior. As results, the followings were made clear: 1) When the jack pattern was changed frequently, the shield behavior obtained by the newly developed survey system had higher accuracy, compared with the shield behavior obtained by the conventional system. 2) When segments were erected on a curve section, the change of direction angle during advance returned to half due to the loss of jack moments, the copy cutter effect and the ground condition.
