The next generation of rolling stock to hit the city’s tram network promises to deliver the holy trinity of improvements in energy efficiency, passenger safety and reliability.
This article was originally published in the November 2024 issue of create with the headline “New trams are all class”.
When Melburnians first boarded a horse-drawn tram 140 years ago, it opened up the suburbs and encouraged people to move to areas now considered inner-city, such as Preston and Northcote. Today, Melbourne boasts the world’s largest tram network, with more than 500 trams running up and down 250 km of double track.
This demands a constant cycle of innovation and upgrade, a cycle that’s clearly visible across the six generations of trams to have thus far operated across the city.
Onboard energy storage
Designed to meet the requirements of the Victorian Government through a competitive tender process, the new G Class fleet, the seventh generation of trams to run on the network, will be built by Alstom in Dandenong.
The first 100 of these accessible, low-floor trams, based on Alstom’s proven Flexity 2 platform, are set to replace some of the longest-serving high-floor trams (the Z, A, and B Class) still in service, with testing of the new fleet commencing in 2025.
While the G Class boasts many new features, the headline upgrade is the onboard energy storage system (OESS). Alongside more modern traction motor equipment, LED lighting, and other energy-efficient equipment this will lead to a 30-40 per cent reduction in energy consumption per passenger.
“The OESS is a roof-mounted lithium-ion nickel manganese cobalt battery cell pack consisting of two batteries with a 48.9 kWh capacity,” said Dr Himani Mazumder, Principal Mechanical Engineer at the Victorian Department of Transport and Planning, in the Rolling Stock Development team overseeing the development of the G Class trams.
“The main purpose of the battery is similar to that of a hybrid car. It assists in providing power when the vehicle is accelerating and captures energy from regenerative braking.
“But as an added feature, it will also be able to trickle recharge from the overhead wiring, effectively time-shifting part of the tram’s current draw away from times when it would be accelerating to moments when it is stationary or coasting.”
This technology not only benefits the vehicles, but also the entire network, Mazumder explained.
“It will assist acceleration once the power being drawn by the tram from the overhead line exceeds a current of 600A. This is referred to as ‘peak shaving’ and supports operations across the network by helping to manage power demands in each substation’s section, while allowing the tram to accelerate and keep its timetable.”
The reduced power draw will help limit the need for capacity upgrades across the tram power-supply system in the initial rollout, saving significant capital expenditure.
Melbourne’s tram network is already extremely efficient, servicing more than 200 million passengers each year using approximately 82 GWh of electricity. The OESS promises to improve this even further with the introduction of the first 100 new trams expected to reduce this demand by 6.8 GWh.
It’s another environmental tick for Melbourne tram travel following the Victorian Government’s Solar Trams initiative, announced in 2019, where 100 per cent of the energy used by the network is offset by new solar generation capacity. This made network operation effectively carbon neutral.
Significant evolution
Though built on a similar base product as the recently delivered E Class trams, the G Class is a significant evolution, Penny Vorvolakou, Project Engineering Manager from Alstom, said.
“A tram is no longer a box on wheels being propelled up and down a city street,” she said, pointing to the innovative technology Alstom is deploying in the G Class.
Innovative elements include smart vehicle safety systems such as forward obstacle detection assistance and correct-side door opening technology.
Simultaneously, the network is rolling out an enhanced automatic points system, which automatically switches points to reduce the potential for human error and wrong route selection, providing greater capability to share onboard vehicle diagnostics and performance telemetry in real time from the tram to the operational centre.
“We are customising a mature design for Melbourne’s needs, ensuring [the] specific challenges and needs of the local network and passengers are met.”
This includes elements based on feedback from human factors testing prior to construction and experience from the E Class tram, which was also delivered from Alstom’s factory in Dandenong.
Safety a priority
With 75 per cent of Melbourne’s tram network shared with other vehicles, safety is a top priority in the design of the G Class trams. The final design has several advanced systems integrated to protect both passengers and pedestrians.
This includes the Obstacle Detection Assistance System, a game-changer in terms of tram safety according to Mazumder.
“It’s designed to recognise any obstacle in the tram’s path that exceeds a specific size, allowing the driver to react swiftly and effectively,” she said. “It can be adapted to any track environment.”
Pedestrian safety is also a major concern, with 47 incidents involving pedestrians in 2023. “The tram’s exterior cab design has been optimised to meet modern pedestrian protection standards, reducing the risk of injury in the event of a collision.”
This includes a safety bar under the front bumper that deploys when the emergency brake is applied. In the event of a collision, it prevents the pedestrian from being dragged beneath the tram.
The proposed side door opening technology would mean the doors will only open on the correct side at each stop, Brooks said. “This system would use wayside-mounted tags and the tram’s vehicle management system to help maintain passenger safety.
“New accessibility technologies include hearing aid loops and clearer passenger information systems.
“The low-floor trams are also accessible for passengers using wheelchairs or mobility aids, with an increased proportion of accessible seating.”
Locally manufactured
From a local manufacturing perspective, the G Class is a big win. The first weld to the final coat of paint will be completed at Alstom Dandenong, with a 65 per cent local content requirement across the entire project, including local materials from Australian suppliers.
The project is helping to support 1900 jobs across the state, including the manufacturing, maintenance and operation of the new trams.
Designing a tram to fit in with such an established network was not without its challenges, according to Steve Brooks, Alstom’s NGT Interface Engineer.
“Designing a tram to be compatible with all locations and conditions of the world’s largest network required careful consideration to meet all operational scenarios and passenger needs.”
The result is a modern, safe, energy-efficient tram with a higher passenger capacity than the models it is replacing.
