The excavation of a station box at a record-breaking depth of 50m below Brisbane’s CBD as part of the Cross River rail underground station on Albert Street has been completed.
The construction of the Albert Street station is Brisbane CBD’s first new train station in more than 120 years.
The fully excavated station box is about 46.4m below ground at the main bottom (B10) level, and almost 50m below ground level at its deepest point at sump level (about 15 storeys).
While the station platform will be 31m below ground, supporting equipment such as tunnel ventilation fans and hydraulic plant rooms mean the station box needs to be excavated deeper.
About 47,305 cubic metres of spoil was removed during excavation – the equivalent of about 19 Olympic swimming pools. Excavation involved the installation of 340 rock anchors and over 1500 bolts, as well as 4,500 cubic metres of shotcrete.
Acting Premier and Minister for State Development, Steven Miles, said the station box for the new station was about 50m deep at its lowest point – almost double the previous record of 26m set during Queen’s Wharf construction.
“This dig, in the heart of the CBD, has smashed the previous record, making it the deepest in Brisbane’s history,” Mr Miles said.
“This milestone for Cross River Rail is yet another example of the sheer scale of this project.
“To give an idea of the size, if this was an underground carpark, it would be about 15 levels deep, with excavation generating enough spoil to fill 19 Olympic-sized swimming pools.
“The Myer Centre carpark just up the road has a depth of 22m, and this is over double that.
“It is a credit to the over 250 workers on site who achieved this despite challenging engineering conditions in between high-rise buildings in the middle of a bustling CBD.”
Following excavation, work is underway on permanent building structure works, including drainage, waterproofing and concrete works.
When completed, the station building itself will be about 40m above ground at roof level.
“The end of excavation means the most intensive period of work on site is now complete, and we thank those living nearby for their patience and understanding while the work took place,” Mr Miles said.
“As the project progresses this year, we’ll start to see the stations themselves take shape here at Albert Street, but also at our other underground station sites and in the tunnels themselves.
“This month we saw some of the first rail delivered to the Gabba site, which will soon be running down the tunnels.
“The Cross River Rail project has great momentum, and we continue to smash milestone after milestone to the benefit of the Queensland economy.”
Queensland Transport and Main Roads Minister, Mark Bailey, said that the station box formed only one half of the total station area being excavated.
“While excavation of the 50m-deep station box cavern has been completed, we continue to work away on the adjoining 290m-long station cavern,” Mr Bailey said.
“The Albert Street station will have entrances at both ends, dramatically improving connectivity to not only Botanic Gardens, QUT Gardens Point campus and the new Queen’s Wharf Brisbane development but also Elizabeth Street and Queen Street Mall.
“It’s hard to grasp just how big these stations will be, but just imagine some of Brisbane’s tallest skyscrapers laying horizontally underground.
“With over 67,000 people expected to use the Albert Street station each weekday by 2036, these long platforms are definitely needed.”
Mr Bailey stressed the importance of the new Albert Street station, especially for the 2032 Olympic and Paralympic Games.
“We know how important Cross River Rail was in Queensland’s winning Olympic bid and the crucial role it will play in unlocking the rail network bottleneck over the Brisbane River,” Mr Bailey said.
“As our population continues to boom, I’m sure the extra services we can provide across the whole network will be warmly welcomed by commuters, tourists and games-goers alike.”
Construction of the Albert Street station building is expected to be completed in late-2023.