The provided diagrams illustrate the specifications of two distinct underground tunnel systems constructed in Australian cities. Overall, it is evident that the second tunnel, built later, is more extensive in length and depth, accommodates more traffic, and required a substantially higher financial investment compared to the first tunnel.
The first tunnel, constructed between 1986 and 1998, was built under a bridge in a sandy environment. It spans a length of 2.2 kilometres at a depth of 1.5 metres. The total cost for this project was $555 million. In terms of capacity, the tunnel features two lanes, with each lane accommodating two vehicles side-by-side.
In contrast, the second tunnel was built beneath a city area between 2002 and 2006. This project involved excavating through stone and clay at a greater depth of 2.5 metres. Stretching 3.6 kilometres, this tunnel is significantly longer than the first. Reflecting its larger scale and more complex construction, the cost rose to $1.1 billion. Furthermore, this tunnel provides a higher capacity, featuring three lanes that allow for a greater volume of traffic compared to the earlier system.