Different methods can be applied for the construction of sewer sanitary system crossing under viaduct railroad tracks. The selection of construction technique is based on some parameters like nature of the soil at project site, sanitary sewer location in elevation and plan in relation to viaduct footing, size of sanitary sewer system and type of viaduct footing. It is recommended to utilize tunneling approach provided that the distance between sanitary sewer and viaduct footing does not create problems and the soil in the area is stable. If such conditions are met, then the selected construction technique would be both cost effective and safe. However, special methods of sheeting and bracing which prevents the failure of soil beneath viaduct footing should be considered if the aforementioned conditions are not realized.