An Introduction to Horizontal Directional Drill Installation of High-Voltage Transmission Lines and Other Duct Banks: Improving on Conventional Overhead Transmission Lines

Horizontal Directional Drill (HDD) installation of high-voltage (HV) transmission has proven practical, and in some cases, less costly than traditional overhead options. Petrochemical facilities located on waterways provide excellent opportunities for underwater HDD-installed transmission lines. These designs can provide significant safety advantages as well as improve system reliability. They eliminate the height restrictions associated with overhead lines, reduce air traffic obstructions, and reduce the weather-related concerns typically associated with traditional overhead transmission lines, especially highly elevated transmission line crossings over waterways. They also offer significant opportunities when expanding existing facilities and designing for Prevention through Design by eliminating the overhead transmission and their associated contact risks throughout the life of the installation. Each HDD-installed transmission line is different and can create significant challenges; however, the benefits associated with this technology can significantly outweigh the effort. This article reviews some of the challenges associated with long, high-capacity transmission line installations, along with their associated solutions as incorporated in previous projects. This article does not cover the smaller and shorter HDD installations typically associated with electrical distribution commonly used to cross streets, highways, or feed commercial facilities.