Figure 18.—Ohio River crossing of the Baltimore and Ohio at Benwood, West Virginia, completed in 1870. Bollman deck trusses were used in the approaches on both sides. (Photo 693, Baltimore and Ohio Collection, Museum of History and Technology.)
Figure 19.—Patapsco River crossing of the Baltimore and Ohio between Thistle and Ilchester, Maryland. (Photo 695, Baltimore and Ohio Collection, Museum of History and Technology.)
As already mentioned, the few available rolled-iron shapes were of relatively small area and quite unsuitable for use as columns unless combined and built up in complex fabrications. The normal practice at the time was to use cast compression members in iron bridges and structures, with their sectional area so proportioned to the length that a state of tension could not exist. In the case of long members, this naturally meant that an excessive amount of material was used.