The diagrams compare the design of two underground tunnels in two distinct cities in Australia.
Overall, it can be seen that the more recently built tunnel, which facilitates urban traffic, displays more advanced features at twice the cost of the older, river-spanning one.
The construction of the first tunnel, which cost 555 million dollars, began in 1986, and not until the next 12 years was the route utterly finished. It stretches from one end to the other of a bridge over a river, covering a distance of 2.2 kilometres. Additionally, this tunnel, which could accommodate four lanes of vehicle traffic, goes 1.5 meters underneath a surface of sand.
Meanwhile, the second tunnel was constructed from 2002 to 2006, necessitating one-third of the total building time for the aforementioned tunnel. With a price tag of 1.1 billion dollars, this tunnel has a span of 3.6 kilometres and lies beneath an overground motorway. Besides being longer than the former tunnel, it provides more space for vehicles as well, at 6 lanes. The more modern building technology is further reflected in the fact that this route went 2.5 meters deep in terrain composed of clay and stone.