Timber-lattice bridges have become a forgotten piece of the UK's railway history. Yet these bridges represent a crucial step in the development of iron-lattice and iron-truss bridges. Moreover, these timber bridges also provide further evidence of early interactions between British, Irish and American engineers. This paper looks at the development of timber-lattice bridges in the UK, documenting the designs of individual engineers, their influences and design methods. It will demonstrate that British bridges differed from those of North America. Constructed before engineers had the means of accurately calculating loads acting within structural elements, members were frequently undersized. Consequently, most bridges performed poorly, especially under dynamic loading, resulting in most being altered post-construction. Despite their shortcomings, most bridges did survive long enough to make them financially viable and typically longer than many simplistic forms of timber bridges.

British and Irish railways once featured several thousand timber bridges and viaducts. Modern and contemporary sources suggest that these structures were replaced due to problems with decay. Consequently, this decay presents a significant challenge to proponents of modern timber bridges, with their critics arguing that timber structures would fail to satisfy the service life requirements. In reality, what actually had a greater influence on their performance and longevity; timber's inherent liability to decay, or deficiencies in their design and construction? This paper presents the findings of the first major study on nineteenth-century timber bridges in the UK, aimed at documenting the design and construction methods used, and their subsequent performance. Despite problems with decay, many nineteenth-century railway bridges lasted beyond their expected design life. Moreover, most problems affecting their life span were the result of erroneous design practices coupled with poor construction and maintenance, rather than inherent material deficiency. Crucially, they could be either obviated or limited through better detailing, modern preservatives and a more judicious consideration of structural forces. These nineteenth-century structures provide crucial lessons in timber bridge design for modern engineers as the profession looks to provide more sustainable infrastructure both now and in the future.

The nineteenth century saw numerous bridge failures across the UK, Europe and North America as engineers struggled to master the difficulties of constructing in iron, particularly cast iron. Following the collapse of Robert Stephenson's (1803–1859) Dee Bridge in 1848, engineers have focused on these disasters in order to improve both safety and the overall performance of bridges. In comparison, little attention has been paid to the safety record of the thousands of timber railway bridges built across the UK. This paper seeks to readdress this imbalance. Drawing upon primary sources, it provides the first comprehensive review of the safety record of timber railway bridges constructed between 1840 and 1870. It discusses the perceptions of contemporary engineers and the general public, focusing on issues regarding material selection and their ongoing assessment and maintenance. It also highlights the safety advantages of certain bridge types, particularly where engineers faced geotechnical problems, such as slips and subsidence of embankments. By documenting the accidents associated with timber bridges, it is shown that despite problems with decay, the threat of fire and problems under dynamic loading, timber bridges were considerably safer than cast-iron bridges. Of the thousands constructed in the UK, none failed under service.