 However, after 26 such examples were built the design was altered with high running plates mounted above the driving wheels and a more comfortable full-width pressed metal cab of Canadian design, a feature incorporated at the request of Victorian Railways Chief Commissioner and former Canadian Pacific Railway Transportation Manager Thomas Tait.These became hallmarks of all subsequent VR steam locomotive designs.Although the Dd was considered to be a successful design, it had a key shortcoming in that its boiler performance was not sufficient for the traffic demands being placed on it.