| dc.description.abstract | Microtunneling is now commonly used in constructing the sewerage collection system. Due to the lack of experience in the early stage, construction budgets of microtunneling is formulated according only a handful of cost factors. This sometimes resulted in great cost variance during the construction stage, preceded by time-consuming changes or even disputes.
The purpose of this work is to summarize the practical experience of using the microtunneling technology for the past two decades and to devise a wide set of cost factor on which a more accurate construction budget can be based. Five aspects of external influence factors are examined, including existing underground utility lines, ground conditions, site locality, project administration and work requirements. The work breakdown structure of microtunneling is comprised of three branches, including those of the entrance work pit, horizontal advancing sections and arrival work pit. Practical experience is obtained by a questionnaire survey, in which 32 experts are surveyed with 20 of them considered complete and valid.
The result shows that the key cost factors mostly relate to underground utility lines. In contrast, factors related to ground classification, site locality and client requirements can be omitted. The proposed cost adjustment model is practically useful. With the test case adopted in the study, the budgeted cost can better represented the actual cost incurred in the construction stage. | en_US |