The presented diagrams show information about two different road tunnels in two Australian cities.
Overall, the older tunnel is smaller in terms of depth and length compared to the one that was completed in 2006. In addition, the 2006 tunnel accommodates more traffic lanes with higher construction costs.
Looking first at the tunnel built in 1998, what is most striking is the function of the tunnel, which connects the traffic on both sides of a river, reducing traffic load on the existing bridge above. It has a depth of 1.5 meters and a length of 2.2 kilometers, and was built under a layer of sand. The city council spent 12 years and 555 million dollars to complete the tunnel. Inside, the tunnel is equipped with four lanes.
Regarding the tunnel introduced in 2006, unlike the previous one, this tunnel was built under a main road. It is deeper and longer than the 1998 tunnel, with a depth of 2.5 meters and a length of 3.6 kilometers. Another major distinction is that the tunnel was built beneath a different material surface, stones and clay, which required a different construction technique. Moreover, it has six lanes, which better relieves traffic volume in comparison with the 20th-century tunnel. Finally, the construction expenditure on this project was 1.1 billion dollars, and the project’s duration was only a third of the older tunnel’s.