Laurie gave cautious, provisional approval to Lyman and Rapallo viaducts, and the Railroad Commissioners in turn certified the line for operation. Varrugas Viaduct collapsed in 1889 as a consequence of the increase in weight and speed of rolling stock in the 20 years since its construction. The only other known contemporary example, Kinzua Viaduct in Pennsylvania, is said to have undergone massive alteration to accommodate heavier loads. While most of the construction details of Lyman can be inferred from patent records and the Laurie report, there is no assurance that the actual construction followed the specifications, particularly because the structure was so innovative that unanticipated problems probably arose during construction. Furthermore, no documentary evidence exists for the fabrication details, such as the means of finishing column ends.
Pictorial depictions are not- large or precise enough to portray the joints and other details.
Lyman Viaduct has much to tell about technological change in industrializing America.