Cost comparison of horizontal auger boring and open-cut construction methods for culvert installations

The underground infrastructure serves as the primary means of transporting our indispensable needs such as drinking water, wastewater, gas, oil, and power. Culverts are an important part of this infrastructure. They provide a pathway for water to pass under roadways and railways, and prevent flooding. However, like most other assets, culverts deteriorate over time and require replacement. Horizontal auger boring (HAB) offers several advantages over the conventional open-cut method for installation of culverts. In addition to the well-known advantages of trenchless technologies, in terms of less traffic and environmental disruptions, they can provide economic replacements. The main research questions were: (1) Is HAB an economical alternative to the open-cut technique for culvert installations? (2) Is it more economical to use an ODOT (Ohio Department of Transportation) crew instead of a contracted crew? And (3) what are the productivity improvement opportunities that can reduce the installation cost? To answer these questions, three comparisons for HAB and open-cut installations were conducted: (1) comparisons of bid prices, (2) cost comparison of observed installations, and (3) road user cost comparison. The research study also explored areas of potential productivity improvement for the HAB operations. The research findings indicate that the unit costs of the HAB and open-cut culverts installed by the ODOT crews are considerably lower than those installed by the contractors. The research findings also indicate that HAB is an economical alternative for culvert replacement when compared to open cut, for culverts with a depth of cover exceeding three feet.