| dc.description.abstract | Horizontal Directional Drilling (HDD) is a growing method for installation of pipes in urban areas and where ever trenching is impossible or undesirable; such as in crossing rivers, lakes, and railways, and special areas such as airports. This technique utilizes downhole cutting heads to create a pilot borehole before it is enlarged with back reamers to allow pulling back of a product pipe. The utilization of HDD for the installation of underground infrastructure (i.e., water, oil and gas pipes, telecommunication, power conduits, in some cases gravity pipes, and so on), has shown a rapid growth compared to other trenchless technologies. HDD can install a range of pipe diameters from 2 -60 inches utilizing different pipe materials including steel, HDPE, PVC, and ductile iron, with minimum surface and daily life disruptions.Estimation of HDD productivity, project duration, resources, and cost is a difficult task due to variable productivity conditions such as site, soil, project, contractor, and machine conditions. The objectives of this research are to define the significant subconditions that affect HDD productivity by utilizing the analysis of variance (ANOVA) model approach, to develop a productivity prediction model, and to develop HDD user interface as a planning tool for operation. Initially the main productivity conditions and subconditions were identified through literature review and consulting of HDD experts and professionals. An HDD questionnaire was designed, reviewed, and sent to HDD experts (contractors, design engineers and consultants) to collect data addressing HDD operation conditions required for testing significance of subconditions and modeling operation productivity.HDD subconditions that show significance by ANOVA will be used to model HDD productivity in clayey and rocky conditions. This model is applicable in predicting HDD productivity to estimate duration of HDD project, in addition to other project parameters such as quantities of materials required and cost of labor. Applications on HDD productivity model will be useful for consultants and contractors for planning, design, scheduling, and bidding of HDD projects during preconstruction stage, as well as during installation and construction. | en_US |
