Bridges are among the most critical assets in transportation networks; they play a crucial role in connectivity by providing a cost-effective infrastructure to transport people, goods, and services. With the Industrial Revolution, the development of the steel industry allowed constructors and engineers to opt for solutions encompassing long spans and lighter structures, and steel truss bridges were one of the preferred typologies to solve the connectivity problem between two points, presenting a geographical feature. However, the evolution of transportation systems, the extreme climate events resulting from rising climate change, and the ageing of steel truss bridges over the last 100 years have transformed these bridges into vulnerable assets susceptible to local damage and collapse. This research aimed at understanding the structural behaviour of these ageing steel truss bridges subjected to local damage or failures that could propagate in the form of a progressive collapse. This knowledge is crucial in the current context since replacing or retrofitting the entire network of steel truss bridges has proven unaffordable to any government or entity. A laboratory campaign was carried out on a scaled version of a real bridge and a monitoring plan was established to track the changes in the structural behaviour that could confirm a failure propagation phenomenon. The studied bridge has proven to be able to redistribute loads to different structural elements, thus showing its effectiveness in avoiding disproportionate collapse. Results were gathered to propose a monitoring methodology to prevent the collapse of ageing steel truss bridges such as that studied, which represents an engineering emblem of the 20th century.