The Dock Railway is the railway company in Bigg City Port. It was seen on the side tanks of the The Goods Engine that the Dock Railway owns it, it most likely also owns Puffa and all the other engines seen in Bigg City. It also owns the railway bridge that crosses the canal. After the accident in High Tide, it is unknown that the bridge got rebuilt or the Goods Engine being repaired.
The railway and The Goods Engine seem to be based on the New York Dock Railway, which was located alongside the Hudson River, in New York City. It carried out a very similar purpose to the Dock Railway in the TUGS TV series, and even had car float docks and New York Central Tugboat 13.