Three other pony truss spans, also built in the 1950s, have been altered and moved from their original locations but the Foss River Bridge pony truss remains unaltered since its construction in 1951, and is an excellent surviving example of this bridge truss type. Common before the 1940s, pony truss spans became unpopular because their use was limited to short spans and narrow roadways. Over the years, bridges of this type have been replaced because of deterioration, substandard roadway widths and limited load carrying capabilities.