ABSTRACT
Utility lines such as gravity sewer lines (sanitary, storm/drainage, combine), gas mains, water mains, long-distance heating lines, long-distance refrigerating lines, pneumatic conveying lines, refuse disposal lines, oil pipelines, ducts, conduits, and cable lines for electricity-telecommunications-signaling are the basic cost items of any urban management. Since urban areas are environmentally sensitive and include some obstacles on surface such as highways, railways, rivers, canals, buildings, and airfields that are on the path of pipe lines, special care should be taken to not disturb the surface structures and obstacles when dealing with infrastructural systems. There are generally two choices to cope with infrastructural needs of an urbanized area: open-cut trenching (cut and cover) and microtunneling (trenchless technology, pipe jacking, no-dig technology).
