The diagrams compare the design of two underground tunnels 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 first tunnel was constructed from 1986 to 1988, costing 555 million dollars. It stretches from one end to the other of a bridge over a river, covering a distance of 2.2 kilometers. In addition, this tunnel, which could accommodate four lanes of vehicle traffic, went 1.5 meters underneath a surface of sand.
Meanwhile, construction of the second tunnel began in 2002, and it was not until 2006 that the route was opened for traffic. With a price tag of 1.1 billion dollars, this tunnel has a span of 3.6 kilometers 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.