The underground construction method known as horizontal directional drilling, or HDD, has enabled the underground installation of critical public infrastructure for more the 50 years, and the use of the technique continues to expand, says Fulton Schools Professor Samuel Ariaratnam. One of the foremost experts on HDD, Ariaratnam see its benefits multiplying, especially in its uses for infrastructure systems in urban environments. HDD allows for infrastructure to cross roads, river, lakes and neighborhoods with little disruption to the surrounding areas. It also works well for installation of water, sewer, oil, electric, natural gas, cable and telecommunications lines. Still, there are challenges to overcome in successfully using HDD, Ariaratnman emphasizes. Doing it right requires meticulous planning, well-honed skills and extensive understanding of geological and soil conditions, plus the use of the right tools for various situations.