HDD DEALMAKERS AND DEALBREAKERS

摘要

Advantages of HDD have become widely known, prompting more diverseapplications and feasibility evaluations. While many site specific conditions contribute to thebasis of chosen installation technologies, a few hinge issues can often serve as key determinantsfor selecting HDD. Six hinge issues are discussed in the context of a collection of case histories,some where HDD was selected, and some where HDD was initially preferred but in the end wasnot used. Issues include constraints by the user and from site, soil, structural, hydraulic andenvironmental aspects. Chosen case histories include a broad range of pipeline sizes andapplications. Contrasting examples are given for how the technology decisions developed, werecontractually assigned, and how projects were concluded. Comparison summaries are providedand conclusions are made to help identify when clear HDD advantages or obstacles and riskfactors are present. Comparisons include open trench, microtunneling, pipebursting and CIPP.