Project report: Minimising the impacts on the Metro Tunnel

As Victoria’s biggest public transport project ever, the $11 billion Metro Tunnel is set to change the face of Melbourne’s rail network. How is the team behind its construction managing impacts from construction noise and vibration on the massive project? As Victoria’s biggest public transport project ever, the $11 billion Metro Tunnel is set to change the face of Melbourne’s rail network. How is the team behind its construction managing impacts from construction noise and vibration on the massive project? 

Earmarked as Victoria biggest public transport project ever, the $11 billion Metro Tunnel – the first metro project in the state since the City Loop was built more than 30 years ago – is well on its way to becoming a reality.

The Cross Yarra Partnership (CYP) consortium, comprising Lendlease Engineering, John Holland and Bouygues Construction – contracted by Rail Projects Victoria on behalf of the Victorian Government to build the $6 billion tunnels and stations package – has been making significant headway on project.

This key package involves main tunnelling works, construction of stations and fit-outs, mechanical and electrical systems and maintenance services for the infrastructure delivered.

Major works are now underway across the Melbourne CBD. Central areas such as City Square are at the heart of the works, with construction crews digging below the city to build the brand new underground station there.

With such close proximity to buildings, residential properties and public thoroughfare, such a significant undertaking needs to take into account every aspect –  big and small – that could affect people and businesses in the city, including physically, socially and environmentally.

Comprising aboveground and underground works, the question surrounding the Metro Tunnel project is: how are those tasked with delivering the momentous project ensuring construction activities minimise noise and vibration on the surrounding busy urban environment?

Peter Wilkinson, Acting CEO of Rail Projects Victoria (RPV) – the state government body responsible for delivery of the Metro Tunnel project – talks to Roads & Infrastructure Magazine about the challenges around construction vibration and noise impacts on the tunnels and stations portion of the project and what is being done to safely and effectively reduce their effects on the public.

Onsite measures 

One of the large challenges on the project is the management of impacts from construction, particularly in such a busy urban environment, and has been front and centre throughout the project’s delivery so far.

“We’ve been working with relevant stakeholders since 2015 to ensure any concerns are addressed as early as possible,” Mr. Wilkinson explains, adding that all Metro Tunnel sites have been rigorously assessed for noise and vibration impacts.

CYP is also analysing any potential impacts from construction and implementing appropriate mitigation measures.

Mr. Wilkinson says several noise reduction measures are already in place on the tunnel’s various sites, including acoustic sheds, noise walls and blankets, all of which he says are recognised as industry best practice. “In addition, noise and vibration monitoring is used on all sites,” he adds.

“We are also using cutting-edge technology during piling works at Parkville to break back the piles, which will minimise noise and vibration,” Mr. Wilkinson explains. “The method involves the use of an expanding mortar to create pressure and generate a perfectly horizontal cut, so the top layer of concrete can be easily removed by a crane.”

Prior to Metro Tunnel works beginning near heritage-listed buildings and other properties, comprehensive condition surveys are undertaken as well as ongoing modelling and monitoring of the potential impact of construction activity.

Maintaining the message

While physical measures are key to reducing impacts on the massive project, Mr. Wilkinson says stakeholder and community engagement is important to ensure everyone is aware of upcoming works and disruptions.

“A key focus of the Metro Tunnel Project is engaging with the community and stakeholders on the design and construction of the five new underground stations,” he says.

The project has undergone an extensive public planning process, backed up by Environmental Performance Requirements developed as part of the Environmental Effects Statement planning process, which require noise and vibration levels to be monitored and appropriately mitigated.

“Noise and vibration is unavoidable on a project of this magnitude, but every effort is being made to mitigate and manage potential impacts,” he says.

The project team is continually reviewing construction noise management and seeking methods to reduce the impact of noise and vibration, which Mr. Wilkinson says are the same types of issues routinely managed on similar tunnel projects around the world.

To keep the community and stakeholders informed about works and disruptions, the Metro Tunnel team has held a number of information sessions for residents and businesses and presented to resident groups and owners’ corporations to maintain a high level of communication throughout the project. This also involves the continued facilitation of regular one-on-one meetings with stakeholders and residential groups.

“We also host a Precinct Reference Group and Community Reference Groups which include representatives from a variety of stakeholder groups, including residents, businesses and institutions,” Mr. Wilkinson adds. “These groups meet every four to six weeks and provide a two-way forum to discuss upcoming works and provide stakeholders with an opportunity to ask questions or raise specific concerns.”

A dedicated visitor centre located opposite Melbourne Town Hall on Swanston Street – Metro Tunnel HQ – also provides the public with insight into the progress of the project and its benefits. Viewing windows at City Square, Scott Alley and on the corner of La Trobe and Swanston Streets give passers-by a glimpse of the tunnel’s construction sites.

As the Metro Tunnel is the first metro project since the City Loop was built more than 30 years ago, Mr. Wilkinson says engagement with teams from other major infrastructure projects around the globe has helped inform the approach to noise and vibration reduction measures employed on the project.

“The Metro Tunnel project has a track record of engaging with teams from some of the largest transport infrastructure projects in the world, ensuring a best practice design and construction approach is implemented,” he explains. “We are learning from other major metro projects around the world, such as Crossrail in London, and implementing best practice noise and vibration management.”

The project team also comprises staff with a significant amount of overseas experience on rail projects in Singapore, the UK, Hong Kong, India and Taiwan to name a few, which Mr. Wilkinson says has many flow-on effects for the Metro Tunnel and the state.

“Attracting this world class experience to Victoria is not only shaping the Metro Tunnel, but is also helping to up-skill the next generation of local rail experts to deliver future projects in Australia and around the world.”

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