Designated as No.100A, it forms part of the long brick viaduct taking the Altrincham branch of the Manchester South Junction & Altrincham Railway through Knott Mill Station. The bridge, designed by William Baker, spans 31.9m. It has six cast iron ribs each made in five pieces and bolted together. The ribs are braced with cruciform cast iron sections. The twin railway tracks were carried on cast iron deck plates. The resident engineer was Henry Hemberow, and the sections were cast by Garforths of Dukinfield. The MSJ&A Railway was Manchester's first suburban railway line.