Structural Aspects of Medieval Timber Bridges

THIS ARTICLE compares our very fragmentary knowledge of large medieval timber bridges with the respectable body of evidence now available, and here summarized, about bridges at castles and moated sites, which, it is suggested, may be relevant to larger bridges. Nearly all the moat-bridges, from the late nth to the 16th centuries, are structurally similar in that their posts are not earth-fast but tenoned into transverse sole-plates, but the enduring type, with lateral braces, or shores, symmetrically disposed, does not appear until the ijth century. Parallel with these are various specialized forms which are stabilized by additional, longitudinal plates. In the British Isles earth-fast piles were of very limited use in minor bridges but may have become usual in major bridges in the late middle ages.