Education Program definitions
Metro Tunnel definitions
The Metro Tunnel is Victoria’s largest ever public transport infrastructure project. The word infrastructure refers to the basic structures and facilities we need to make our world work. The Metro Tunnel will improve our rail infrastructure but other types of infrastructure include roads, power supplies, water and sewerage, hospitals and schools.
To understand our big project you’ll need to learn some big new words. Here they are, along with what each of them means.
Knocking down buildings to make way for something new. One of the earlier stages in the Metro Tunnel Project was demolishing some city buildings so that we could dig down to create the new underground stations as well as entrances at the surface. In time there will whole new buildings on top of these stations with room for shops, offices, public spaces and even apartments on top.
Archaeology is the study of human history by digging up remains from the past and examining them to see what they can tell us about how people lived a long time ago. Archaeologists take great care as they do their job. They use a trowel to gently scrape away the earth.
After we demolished several buildings in the city to make way for the new Metro Tunnel stations, we had a once-in-a-lifetime chance to examine the landscape of early Melbourne and learn what it could tell us about how our city started, grew and changed. Our teams of Archaeologists found more than a million buried objects. Some were more than 180 years old.
Maybe you already know the word “acoustic” – it means sound or the sense of hearing – as in acoustic guitar. Building is a very noisy business.
Acoustic sheds are giant concrete shells which are placed on top of a construction site to keep all the noise, dust and vibration inside. That’s important when you are working around the clock and building in the heart of the city.
Once we have finished all the noisy stuff and are ready to fit out the new stations, the acoustic sheds will be taken down and replaced with new buildings, plazas and gardens.
Tunnel boring machines
Not “boring” at all - very interesting in fact! On this occasion the word “boring” describes how these gigantic machines chew through the earth, a bit like an insect might bore a hole in wood.
Tunnel boring machines cut through the earth to make the tunnels and also bring in concrete rings to line them as they go. That way the tunnels don’t fall in!
Each tunnel boring machine is purpose built to be exactly the right size for the tunnels we need. They are made overseas and then shipped to Melbourne, where they are loaded into the tunnel entrance and get to work.
Think about what happens when you dig a big hole in the sand at the beach. Have you noticed that as you go deeper the sand starts to fall in around the sides? Maybe you’ve tried to stop this happening by lining your hole with sticks or pieces of driftwood so it keeps its shape.
That’s what piling is all about. When we dig deep holes in the ground, like the ones we will need to access each of our new stations, we need to make sure they don’t collapse inwards. So we drill a row of deep holes around the outside of the underground structure and then fill them with concrete so they become super strong columns that will keep everything in place. Once we have all the “piles” in place and the framework is secure, we can get on with the big job of digging out the cave that will hold the underground station itself.