Since the 1980s, drilling technology has grown and developed exponentially. These machines now allow underground infrastructure to be installed without the need to disturb or remove most of the ground or hard surface above the installed infrastructure. site 
drill tool reamer
Loy Clark drilling rig.
A reamer is pulled back though the pilot hole to enlarge the path for the attached pipe or conduit.
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The oil and gas exploration industries pioneered directional drilling in the '60s. The technology was applied to routing of utilities through urban areas started in Los Angles in the '80s. Electronic guidances has spawned the HDD contracting sector. wikipedia wikipedia
YOUTUBE bMSQTzJxro4 Published Jul 20, 2016.
Cost Comparison between Horizontal Directional Drilling and Open-Cut Construction Methods in Nairobi, Kenya. International Conference on Pipelines and Trenchless Technology. pdf expand 