 He is also credited with constructing the first iron deck girder bridge in the U.S. for the Baltimore & Susquehanna near Bolton in the period 1846–47.He was responsible for so many improvements to the basic Winans camel engine, that the class was referred to as "Millholland Camels".He is credited with designing a 12-wheeled camel engine, built in the P&R shops in 1863.