Great B&O website…amazing this bridge is still used…a record holder?
Proving that if you really want durability, build stone arches.
The Carrolton Viaduct is the oldest still-active railroad bridge, but the Starucca Viaduct and the ex-Pennsy arched viaducts in Pennsylvania are other good examples. Compared to steel brdges, they require little maintenance and no painting. Compared to wood - [(-D]
Of course, the basic design dates back to the Romans - and a lot of their bridges are still in use, too.
Chuck (all of whose bridges are steel [:-^])