These and other tributary streams have been covered in and built over (in some cases serving as sewers), but it is possible to trace their valleys at various points by the fall and rise of streets crossing them, and their names survive, as will be seen, in various modern applications.
The cost of intra-urban railways depends not only on the type of construction, but more especially upon local conditions, such as the nature of the soil, the presence of subsurface structures, like sewers, water and gas mains, electric conduits, &c.; the necessity of permanent underpinning or temporary supporting of house foundations, the cost of acquiring land passed under or over when street lines are not followed, and, in the case of elevated railways, the cost of acquiring easements of light, air and access, which the courts have held are vested in the abutting property.
The chief objects for which the city debt was created were in 1907, in millions of dollars: highways, 24.07, parks, 16.29, drainage and sewers, 15.05, rapid transit, 13.57 and water-works, 4.53.
Mitted to them - as the construction of roads, the cleansing of the sewers and the maintenance of the aqueducts.
Without resorting to this exaggeration, Mommsen can speak with perfect truth of the " enormous space occupied by the burial vaults of Christian Rome, not surpassed even by the cloacae or sewers of Republican Rome," but the data are too vague to warrant any attempt to define their dimensions.