The live loads for superstructure for the several kinds of bridges are given on Fig. 18a, and those for substructure on Fig. 18b. The former include impact allowances, while the latter do not. Fig. 18c records the

weights of metal per lineal foot of span in the superstructures of the various kinds of bridges considered. The live loads for highway and combined-railway-and-highway bridges include the proper allowances for electric-railway cars or trains.

The weights per lineal foot for the flooring are as given in Table 18a.