Why is the viaduct a mixture of brick and metal arches?
At the time the viaduct was being built, the cost of labour was less than the cost of steel. Therefore the brick arches were cheaper to construct than the steel spans. However, the spans over Western Road and the Great Central Railway tracks and sidings had to give adequate headroom for the traffic underneath. The use of steel girders for these spans gave a flat underside to the bridge which reduced its overall height.
