In order to prove that the infrastructure plan was not just talk, the government, with Arthur's urging, began the construction of several major projects, including the subway systems in Sydney, Melbourne, and Saint Arthur Castle.
For large urban cities, subways are extremely important, not only facilitating the movement of people within the city but also easing the connection between various parts of a large city.
Take the current situation in Sydney as an example. Without a subway, even traveling by car from the southernmost to the northernmost parts of Sydney would take more than two hours.
If there were traffic congestion or a high volume of pedestrian traffic along the way, the travel time would be even longer, significantly reducing the convenience of interaction within the city.