The Fed Square entrance to Town Hall Station is opening. See inside

The final piece of Melbourne’s Metro Tunnel will be unveiled to commuters on Thursday as a new connection is unlocked in the CBD.

Almost a full year after the $15.5bn rail link launched, the long-awaited Federation Square entrance to Town Hall Station will finally open to commuters at 4am on October 29.

The brand-new entrance opposite Flinders Street Station will allow for direct ­pedestrian access from Metro Tunnel services to Federation Square and ACMI, and give commuters a closer connection from the train to Rod Laver Arena and the MCG.

For years, major pedestrian links outside Flinders Street Station were hit with closures while construction crews used the site as a “logistics” shaft, allowing teams to “continually feed the project” down a six-storey drop for the construction of Town Hall and State Library stations beneath the city.

In an “engineering feat”, the shaft was then integrated into the Metro Tunnel while trams, traffic and pedestrians buzzed above.

The Federation Square entry is the only portal across the project that is trapezoidal in shape, opening up as commuters come out into the arts and entertainment precinct.

It’s a three minute walk from the entry on ground level to trains below.

Setting the new entrance apart from the rest is mega art piece “Barerarerungar” — a striking 45m installation by First Nations artist Maree Clarke.

The piece is made of 30 large glass panels, which wrap the concrete walls of the entrance and celebrate the five clans of the Kulin Nation.

Featuring imagery of local landscapes, scar trees and traditional possum-skin cloak designs, the piece points back to the site’s history as a meeting place for ancient ceremonies.

Ms Clarke also designed the animal footprint artworks which feature at platforms of all Metro Tunnel stations.

At an exclusive tour before the grand opening, construction manager Will Thay told the Herald Sun the new entrance was one of the most “complex” portals of the project.

He explained how crews had to squeeze a crane into the tight landing space, measuring no bigger than a living area, to install 350kg facade panelling and steel reinforcement.

Then, crews had to build a “mechanical slide” to install escalators, which each came in six sections weighing up to seven tonne.

“It’s such a small shaft compared to all the other shafts around the project, so the construction constraints, the safety considerations, and the engineering work that went into it was quite immense,” he said.

Senior precinct manager of Town Hall Station Emmett Ahern said the portal was always intended to be opened later than others in the project.

Mr Ahern, who has worked on the Metro Tunnel project since its inception more than a decade ago, called the final milestone opening “pretty surreal”.

“All the work that has been done, all the effort and the amount of people involved, decisions that have been made, finally — something I’ve been dreaming of — is people using it,” he said.

“The Fed Square entrance was an important one … it provides a great opportunity and access point for visitors and event goers all year round.”

The opening means commuters have three street-level entrance points to Town Hall Station — Federation Square, Swanston St near the Young and Jackson pub, and at the main City Square entrance near Town Hall.

Passengers can also access Town Hall Station direct from Flinders Street Station via underground subway connections when transferring between City Loop and Metro Tunnel services.

Metro Tunnel Project Office construction director Jim Heron said the opening was a testament to the dedication of builders and engineers on the project.

“They battled on, they finished it, they hit it on time and did it in a difficult environment,” he said.

Town Hall Station is one of the busiest stations on the network, recording 7.7m journeys since it opened.