Using Decision-making Criteria Approach for the Selection of Trenchless Construction Method: A Review Study

Abstract

Trenchless technologies (TTs) are used to install new pipes or repair and replace the old pipes classified in two categories: construction and rehabilitation/ replacement methods. Due to rapid urbanization, new pipe network should be established proportional to the population growth. On other hand, due to issues such as corrosion and aging, a major part of storm sewer, waste sewer, gas, water pipes must be replaced/ rehabilitated every year. Traditional open-cut methods are not applicable anymore disruption to traffic, unsafety, environmental impacts, high cost and so on while the trenchless construction methods are able to address these issues. The construction trenchless methods include horizontal earth boring (no worker entry), pipe jacking and utility tunneling (worker entry). The first one is subcategorized to horizontal auger boring, horizontal directional drilling, pipe ramming, microtunneling, and pilot tube microtunneling and compaction method. In the first part of the current study, the design criteria needed for horizontal auger boring, horizontal directional drilling, pipe jacking, pipe ramming and micro tunneling will be reviewed and discussed. Considering these requirements which are unique for each individual project, the optimum trenchless technology can be proposed for that project. In the second part of this research, based on a concept given in the literature, a hierarchical algorithm is proposed by the author that is defined based on the design requirements and can be used as a decision-making tool to select an optimum trenchless construction method. Sometimes more than one method can be proposed. The best one will be selected based on availability of equipment and skillful team, budget and sustainability principles. Although the trenchless renewal methods are not in the scope of the present study, their respective design criteria are given in the appendices in order to provide a complete collection of design requirements for the all trenchless technologies.