The much-anticipated Metro Tunnel is set to open by the end of 2025, marking the biggest change to Melbourne’s rail network since the City Loop began operating in January 1981.
Twin tunnels underneath the CBD will create an end-to-end train line from Sunbury in the west to Cranbourne and Pakenham in the southeast and connect Parkville and St Kilda Road to the rail network for the first time.
The project includes five new underground stations – Arden, Parkville, State Library, Town Hall and Anzac – and connections to the existing network at Flinders Street and Melbourne Central stations.
The project’s signalling system is being delivered by the Rail Network Alliance (RNA), which comprises Alstom, a Joint Venture of John Holland and CPB Contractors, AECOM, Metro Trains Melbourne, and the State of Victoria.
A first for Australia
As part of the project, a new High Capacity Signalling system has been installed throughout the twin tunnels and on sections of the Cranbourne, Pakenham and Sunbury lines.
The signalling system was delivered by Alstom and uses its world-leading Communications-Based Train Control (CBTC) solution Urbalis Flo (formerly CityFlo 650) system.
This has been in operation along sections of the Pakenham/Cranbourne line since January 2023, and its installation was the first rollout of High Capacity Signalling on an existing network anywhere in Australia.
The benefits of CBTC
The need for mass transit systems with extended capacity is increasing – more people need to arrive at their destination on time, without compromising on reliability or safety. Alstom’s scalable CBTC solutions help to meet this demand.
By wirelessly communicating the location of moving trains to other trains, the railway line and back to signal control centres, train speed can be automatically adjusted to ensure a safe distance from the train in front.
This means the trains can run closer together – compared to conventional signalling which uses stop and go lights – so more trains can run more often.
Alexander Robinson, Rail Control and Project Engineering Manager of Alstom, said: “Our CBTC system is going to enable much more frequent rail services, and it has already done so on the surface areas in the east of Melbourne. It allows trains to arrive every three minutes – with the potential to reduce to two minutes in peak hour.
“Alstom’s CBTC and the Metro Tunnel project as a whole will not just enable higher capacity on the Sunbury Line and the Cranbourne/Pakenham Line, but will also free up space on the existing rail network.
“More space in the City Loop means capacity for other lines to increase services too.”
A bespoke system
The Metro Tunnel project is the first mixed-mode signalling application in Australia, with Alstom combining CBTC with mainline signalling on the same line.
“The system had to accommodate existing trains, such as V/Line and freight trains, as well as the new ones,” Robinson said.
“This meant that the existing signalling design had to be retained to a certain extent, so we created a bespoke system for the customer.”
Creating this tailored solution was quite a complex endeavour.
“Mixing the CBTC system with the existing conventional signalling was probably the most significant challenge of the project,” Robinson said.
“To a certain extent, we had to reverse-engineer Victorian signalling principles that have been built up over the past 100 years and incorporate those rules into modern CBTC signalling technology.”
Robinson said this is where Alstom’s global technology and local know-how came together to meet the needs of the customer.
“We brought in some international expertise from the home of our Product Centre, which is in Pittsburgh in the United States.
“It was great to marry their knowledge with that of our team on the ground in Melbourne, and come up with a solution that was both local and international.”
Punctuality and reliability
As well as more frequent trains, Melbourne commuters can look forward to more punctual and reliable services.
“We have replaced a lot of the older track circuits with modern axle counters, so there has already been an uplift in reliability, and this will continue when the tunnel opens,” Robinson said.
“There will still be a driver on board, but once the trains are within the CBTC area they will be more consistent in maintaining runtime and punctuality.
“Even in the event of a failure of the conventional signalling system, the CBTC trains will continue to run.”
Platform Screen Door technology
Alstom’s CBTC solution delivers Platform Screen Door (PSD) technology that enables the platform and train doors to open at the same time. While in use in many other cities around the world, the technology is a first for Melbourne and has been installed at all five of the new stations as part of the Metro Tunnel project.
“A large proportion of rail safety incidents happen at that train/platform interface, where passengers can come into contact with a moving train,” Robinson said.
“The PSDs bring an extra level of safety by separating passengers from the rolling stock while it is in motion.”
The PSDs can also ensure trains run on time.
“Trains are often late because passengers are trying to board after the doors are closed, or they are still in contact with the train so the driver can’t safely depart. The PSDs can help prevent this.”
Innovating solutions
On most of Melbourne’s rolling stock, the train doors are located inside the car body. This creates additional space between the train door and the PSD, which poses a risk of passenger entrapment.
To mitigate this, Alstom has undertaken extensive design work to ensure passengers are safe at all times.
Skylar (Xin) Qi, System Integration Test Engineer at Alstom, is part of the lab team that is delivering the technology.
“We have come up with a special design for the back of the door, with fins or boxes to fill the gap,” she said.
“If anyone was in that gap when the Platform Screen Doors closed, the doors would reopen because mechanical devices are in place that will detect a person there.”
Qi said the technology has already been through multiple rounds of testing, on site as well as using PSD simulators in the lab.
“Safety is our number one priority,” she said. “If an issue is detected, it is reported immediately and we come up with a plan to resolve it.”
Maintenance savings
Robinson said Alstom’s CBTC solution can reduce the amount of equipment required by operators, saving them money and time spent on maintenance.
“In the tunnel, there’s no need for the existing lineside equipment,” he said.
“We do have large axle counter sections to fall back on, just in case there is a problem, but within the tunnel itself there’s very little wayside equipment – just the radio itself and a few beacons or norming points that help locate the train.
“Having very little wayside equipment means minimal wayside maintenance, as most of the clever equipment is on the train itself.”
This also means not having to access the tunnel to fix track circuits, signals or other wayside interfaces.
“That’s a reduced cost in itself, but more significantly, you don’t have to close the railway line for maintenance.
“In other countries, the CBTC technology has enabled almost 24/7 operation.”
As the modern CBTC system is more software-based than mechanical, Robinson said more data is available to maintenance teams.
“That data can be used to optimise maintenance and react to problems sooner,” he said. “The amount of data can be overwhelming, but Metro Trains has formed a special team to maintain the system.
“Alstom has been working closely with them for the past two years, and they are very competent.
“We have a 10-year service agreement with Metro Trains so we will be providing maintenance support as well.”
Exciting times
Robinson has been involved in the Metro Tunnel project for more than ten years, and he’s excited for opening day.
“The Metro Tunnel will make a major difference, not just for the people who live along the corridor but for a significant number of commuters and other users of public transport in Melbourne,” he said.
“Even in terms of architecture, the new tunnel stations are incredible.
“It’s going to be like nothing Melbourne has ever seen before.”
