ritton trenching machine The December 1914 acceptance trials included a bridging demonstration where a tractor towed two trailers of bridging timbers to a broad ditch; after engineers spanned the ditch, the tractor and trailers were waved across and one of the trailers toppled over the side, collapsing the bridge.[2] After this accident Bacon remarked to Tritton that an armed and armoured vehicle that could lay its own bridge would be of great value.[2] Bacon continued to press Tritton about the idea and designs were drawn up for a m