Skip to main content

TBM launch: tunnelling begins on the NORTH Section of M6 Metro Line

The first TBM on the NORTH Section of M6 Metro Line carried out the first rotation of its cutterhead today, marking the start of tunnel excavation on the Tokyo – Aeroport Otopeni segment. The launch of the machine took place during a ceremony that also included a blessing service for the two TBMs, officiated by priests of the Romanian Orthodox Church, on the works platform of the future Brussels metro station.

The ceremony took place in the presence of the General Director of Metrorex S.A., Mariana Miclăuș, and of high-ranking officials, including Mr Ștefan-Ovidiu Popa, Minister of Transport and Infrastructure, His Excellency Mr Katae Takashi, Ambassador Extraordinary and Plenipotentiary of Japan to Romania, and His Excellency Mr Özgür Kıvanç Altan, Ambassador Extraordinary and Plenipotentiary of the Republic of Türkiye to Romania.

The event also brought together representatives of the central and local public authorities, of Metrorex S.A., of the Contractor joint ventures responsible for carrying out the project works, of the subcontractors involved, and of the Consultant Supervisor.

“This day marks a new milestone in the construction of M6 Metro Line. With the start of excavation work on the NORTH Section, the tunnels towards Henri Coandă International Airport are beginning to take shape. This is a major infrastructure project that will significantly improve public transport and the mobility of residents in Bucharest and the wider metropolitan area, and will also connect the capital with the country’s main air gateway, Henri Coandă International Airport. Metrorex S.A. builds for people, for a sustainable future,” said Mariana Miclăuș, General Director of Metrorex S.A.

By tradition, TBMs are named after saints. The machine launched today is called “Sfânta Parascheva”  (‘Saint Parascheva’), the protector of travellers, whose feast day is on October 14, shortly before the launch. It will excavate the first tunnel of the NORTH Section, on Line 1. The name Parascheva means ‘preparation’, a meaningful name for a machine that paves the way for the metro. The second machine, “Sfânta Ecaterina” (‘Saint Catherine’), will excavate the second tunnel, on Line 2. Saint Catherine is the patron saint of engineers, and the wheel, her symbol, recalls the cutterhead that digs the tunnel. Together, the two names represent both those for whom we are building the metro – the passengers – and those who are building it – the engineers.

Tunnelling on the NORTH Section is carried out in two stages, starting from the launch shaft at the future Bruxelles metro station. In the first stage, the tunnels will be excavated towards the future Tokyo metro station, the connection point with the SOUTH Section of the line. Excavation works began today on Line 1 and will follow on Line 2. In the second stage, the machines will be relaunched from Bruxelles future metro station towards Aeroport Otopeni, on each line. The tunnels will provide the connection with the SOUTH Section of M6 Metro Line, as well as the link between the six stations of the NORTH Section: Washington, Paris, Bruxelles, Otopeni, Ion I.C. Brătianu and Aeroport Otopeni.

The TBM “Sfânta Parascheva” is an EPB (Earth Pressure Balance) machine, with a total length of 103 metres (including the back-up train) and a weight of 602 tonnes (shield – 380 tonnes, back-up train – 222 tonnes). The cutterhead has a diameter of 6.57 metres (excavation diameter). The machine is adapted to the geological conditions along the route – sandy clay, Colentina gravels and dusty sand, with the ground water at a depth of 2-7 metres. The estimated average advance is 14 metres per day, equivalent to 10 tunnel rings of 1.4 metres each. As it excavates and removes the soil, the TBM installs the precast concrete rings that form the tunnel.

Watch the video of the event here: https://youtu.be/TIBMcqqUYXM

The ‘Sfânta Maria’ TBM has reached the future Expoziției metro station

The ‘Sfânta Maria’ TBM has reached the future Expoziției metro station, part of M6 Metro Line.

This is the fourth tunnel segment excavated by the ‘Sfânta Maria’ TBM on Line 2 of the SOUTH Section, on the route between the future Tokyo and 1 Mai metro stations.

To date, the ‘Sfânta Maria’ TBM has excavated 3,671 metres of tunnel and installed 2,445 rings, out of a total of 6.6 km of tunnel to 1 Mai station. This means that 3.7 km of tunnel have already been completed on the Tokyo – Aeroport Băneasa – Gara Băneasa – Piața Montreal – Expoziției segment.

“The two tunnel boring machines on the SOUTH Section are maintaining a good pace of progress, and the project is advancing steadily. The route taken by the ‘Sfânta Maria’ TBM to Expoziției station confirms this. Meanwhile, the ‘Sfânta Ana’ TBM has 855 metres left to reach this station. Every stage completed brings us closer to our goal of reducing heavy traffic in Bucharest. M6 Metro Line will make a significant contribution to the development of urban mobility and will provide a fast, modern connection between the metro network and Henri Coandă International Airport,” said Metrorex General Manager, Mariana MICLĂUȘ.

M6 Metro Line – NORTH Section: TBM components are being transported to Bruxelles station

Metrorex announces that the transport of the components of the two TBMs that will bore the tunnels of M6 Metro Line on the NORTH Section (Tokyo – Aeroport Otopeni) to the construction site of the future Bruxelles metro station has begun.
The two TBMs are EPB (Earth Pressure Balance) machines, each 103 m long and weighing 602 tonnes (including the technological equipment assembly), with a cutterhead diameter of 6.57 m.
Once all the components have been transported and assembled in the launch shaft at Bruxelles station, the TBMs will excavate the two tunnels of the NORTH Section. The estimated average advance is around 14 m per day for each TBM, equivalent to 10 tunnel rings, each 1.4 m wide. The TBMs will pass through layers of sandy clay, Colentina gravels and silty sand, with the water table at a depth of approximately 2–7 m below ground level.

The works are part of the “Bucharest International Airport Rail Access Link Project (Metro Line 6. 1 Mai-Otopeni). Design and Build – Civil Works for Lot 1.2: Tokyo-Aeroport Otopeni”. The transport and preparation of the TBMs for the excavation of the two tunnels of the NORTH Section marks a new important stage in the implementation of the project.

TBM “Sfânta Ana” breaks through the wall of the future Piața Montreal metro station

TBM “Sfânta Ana” broke through the wall of the future Piața Montreal metro station, today, on the alignment of the future M6 Metro Line.

The boring shield excavating the Line 1 tunnel on the SOUTH Section of M6 Metro Line has thereby completed the third tunnel segment on this line, running from the future Tokyo metro station towards 1 Mai station.

The double-track tunnel completed so far between the future Tokyo – Aeroport Băneasa – Gara Băneasa – Piața Montreal metro stations totals almost 3 km. On Line 1, TBM “Sfânta Ana” has excavated 2,838 linear metres and assembled 1,887 tunnel rings.

The length of the underground tunnel that TBM “Sfânta Ana” will complete as far as 1 Mai station is 6.6 km.

“We are content with the progress of works on M6 Metro Line. The breaking through of the wall at Piața Montreal station by TBM “Sfânta Ana” marks another important achievement in the construction of M6 Metro Line. The project is advancing at an efficient pace. M6 will provide a fast and modern connection between the metro network and Henri Coandă International Airport, contributing significantly to the development of urban mobility in Bucharest,” said Mariana MICLĂUȘ, Director General of Metrorex.

The “moles” digging the M6 metro: how a TBM builds the tunnel, ring by ring

The “moles” of M6 Metro Line dig the earth, bring it to the surface and build the tunnel behind them, almost simultaneously. Their technical name is TBM, from Tunnel Boring Machine.

The TBMs “Sfânta Maria” and “Sfânta Ana”, which are working on the SOUTH Section of M6 Metro Line, weigh around 600 tonnes and have cutterheads roughly 6.60 metres in diameter. In length, they come close to a football pitch. They enter the ground, and behind them they leave a circular, reinforced tunnel, ready for the next stages.

The front of the TBM carries the cutterhead, a huge metal disc fitted with cutting tools. It rotates, breaks up the ground and pushes the material into a chamber where the pressure is controlled at all times. The pressure keeps the excavation face stable and allows the machine to advance under control. From there, the material travels onto a screw conveyor, then onto conveyor belts, and out of the tunnel. It is loaded up and taken to authorised sites.

While digging goes on at the front, the tunnel is already being assembled behind the shield.

Segments and tunnel rings

The TBM advances using hydraulic rams that push against the last ring installed. After each advance, an erector lifts the segments, the precast concrete elements, and sets them side by side until a new ring is closed. A gap remains between the concrete ring and the ground, which is filled by injecting a special grout known as bentonite. The operation fixes the structure in place and helps stabilise the surrounding ground.

Then the cycle begins again: excavate, remove the material, advance the machine, install a ring, inject the grout. And so it goes, a few metres a day, month after month.

How the “mole” knows where to go

Tens of metres underground, orientation has nothing to do with instinct. The TBM has guidance systems, sensors and survey reference points tied to the project coordinates. The operators follow the alignment constantly and can correct the direction with very precise adjustments. From the control cabin they monitor, in real time, the pressure in the excavation chamber, the amount of material extracted and the position of the machine in relation to the designed axis. The operating parameters of the cutterhead and of the hydraulic systems, as well as the operations involved in fitting the rings are added to these are.

Under standard conditions, the TBMs on the SOUTH Section of M6 Metro Line in Bucharest advance at an average speed of approximately 1.5 metres per hour. It doesn’t seem like much, until you see what happens during that hour: the machine excavates around 60 cubic metres of material and prepares for the installation of the tunnel’s permanent structure.

An average of 13 to 14 rings are installed in 24 hours. The teams work in three shifts and the activity is continuous, with the breaks as required for checks and maintenance. The pace varies according to the ground, the recorded parameters and the maintenance work.

Romania’s “moles”: from the metro to tunnels through the mountains

TBM technology is not being used in Romania for the first time. On M5 Metro Line in Bucharest, the excavation was carried out by “Sfânta Varvara” and “Sfânta Filofteia”.

On the Brașov – Sighișoara railway line, on the Apața – Cața subsection, four TBMs are at work, “Eleni”, “Varvara”, “Alexandra” and “Konstantina”, on the Ormeniș and Homorod twin tunnels. The railway machines have a different diameter and work in different geological conditions, but the principle is the same: controlled excavation, removal of the material, immediate installation of the structure and monitoring of the parameters.

The names follow a long tradition in tunnelling projects. Saint Barbara is regarded as the protector of miners and of those who work underground. On M6 Metro Line, the tradition continues with “Sfânta Maria” and “Sfânta Ana”.

What happens at the surface

Although the activity takes place underground, the operation of the TBM is backed by an extensive monitoring system. The pressure in the excavation chamber, the amount of material extracted, the route of the machine and the soil characteristics are checked at all times. In the areas within the zone of influence of the works, special equipment is used to monitor the ground and the buildings.

The underground route to the airport

M6 Metro Line will have 14.2 kilometres of double track and 12 stations, and will create the first direct metro connection between Gara de Nord and Henri Coandă International Airport.

The video shows how the machine advances and how the concrete segments become, ring by ring, the structure of the future tunnel.

Press “Play” and step inside a TBM for a few minutes.

Progress on M6: TBM “Sfânta Maria” breaks through at Piața Montreal station

The Tunnel Boring Machine (TBM) “Sfânta Maria” broke through the wall of the future Piața Montreal metro station, today, on the alignment of the future M6 Metro Line.

Representatives of the Ministry of Transport and Infrastructure and of Metrorex attended the event.

The boring shield “Sfânta Maria” is excavating the Line 2 tunnel on the SOUTH Section of M6 Metro Line, and today it completed the third tunnel segment on this line.

The tunnel completed so far by the machine – 97 metres long, weighing 600 tonnes, with a cutterhead 6.60 metres in diameter – between the future Tokyo, Aeroport Băneasa, Gara Băneasa and Piața Montreal metro stations, totals almost 3 km (2,836 linear metres) excavated and 1,895 tunnel rings assembled.

The length of the underground tunnel that TBM “Sfânta Maria” will complete to 1 Mai station is 6.6 km.

“Metrorex continues to build for people, for the city, for Romania and for a sustainable future. The breaking through of the wall of Piața Montreal station by TBM “Sfânta Maria” is another important milestone in the construction of M6 Metro Line. The pace at which the works are advancing is the result of the good coordination between everyone involved in the project, from the contractors to the funders. M6 Metro Line will provide a fast and modern connection between the metro network and Henri Coandă International Airport, contributing significantly to the development of urban mobility in Bucharest,” said the Director General of Metrorex, who attended the event.

Progress on M6: TBM “Sfânta Ana” breaks through at Gara Băneasa station

March has begun on the SOUTH Section with the completion of the second tunnel segment, roughly 2 km long, between the future Tokyo, Aeroport Băneasa and Gara Băneasa metro stations, on Line 1.

TBM “Sfânta Ana” has excavated 2,006 metres and installed 1,334 tunnel rings, making a decisive contribution to the progress of the works.
With high-performance TBMs and sustained effort, we are building a new metro line for Bucharest, step by step.

The length of the metro tunnel that TBM “Sfânta Ana” will complete up to 1 Mai station is 6.6 km.

The boring shield “Sfânta Maria” has reached Gara Băneasa

The ‘Sfânta Maria’ TBM broke through the wall of the future Gara Băneasa metro station today, on the route of the future M6 Metro Line.

The boring shield “Sfânta Maria” is excavating the Line 2 tunnel on the SOUTH Section of M6 Metro Line, and today marks the completion of the second tunnel segment on this line.

The tunnel completed so far by the giant machine (TBM “Sfânta Maria” is 97 metres long, weighs 600 tonnes and has a cutterhead 6.60 metres in diameter), between the future Tokyo, Aeroport Băneasa and Gara Băneasa metro stations, totals 2,006 metres excavated and 1,334 tunnel rings assembled.

The length of the underground tunnel that TBM “Sfânta Maria” will complete up to 1 Mai station is 6.6 km.

“We are starting 2026 by marking yet another significant milestone in the construction of M6 Metro Line! The progress of both tunnel boring machines – the ‘Sfânta Maria’ TBM and the ‘Sfânta Ana’ TBM – is in line with the construction schedule for building the civil works for the SOUTH Section of the future M6 Metro Line! The “Sfânta Maria” machine has arrived safely at Gara Băneasa, whilst the “Sfânta Ana” tunnel boring machine is also heading towards this destination, having already covered over 1,600 metres and assembled 1,076 tunnel rings” said Mariana Miclăuș, Director General of Metrorex.

Metrorex continues to build for people, for the city, for Romania and for a sustainable future.

Second tunnel segment completed on M6 Metro Line

Today, the “Sfânta Ana” boring shield has broke through the wall of the future Aeroport Băneasa metro station on M6 Metro Line.

The giant machine began excavating the tunnel on Line 1 on May 28, 2025, from the future Tokyo metro station.

This event marks the completion of the first double-sided tunnel segment on the SOUTH Section of the future M6 Metro Line, with Line 2 having been finished over the same distance by the “Sfânta Maria” TBM in the middle of the previous month.

The segment completed by the “Sfânta Ana” boring machine amounts 900 linear meters excavated and 600 tunnel rings assembled!

We are glad that the two boring machines are keeping pace with the schedule for completing the structural civil works for the SOUTH Section of the future M6 Metro Line!

The TBMs “Sfânta Maria” and “Sfânta Ana” will excavate the 6.6 km long underground tunnels, on which the six stations and six interstations of the alignment of M6 Metro Line, SOUTH Section, 1 Mai – Tokyo, will be built.

Metrorex continues to build for people, for the city, for Romania, and for a sustainable future! 

The “Sfânta Maria” boring shield has reached Aeroport Băneasa

Today, the “Sfânta Maria” TBM broke through the wall of the future Aeroport Băneasa metro station, crowning the joy of the recent celebration on August 15.

Excavation of the tunnel on Line 2 has began on April 9, 2025, at the future Tokyo metro station, and during this period the first tunnel segment on the SOUTH Section of the future M6 Metro Line has been completed.

In figures, this segment represents 902 linear meters excavated and 602 tunnel rings assembled!

Meanwhile, the “Sfânta Ana” TBM is executing the first tunnel segment on Line 1 of the SOUTH Section. At this point, it has excavated over 406 linear meters and assembled over 265 tunnel rings.

The TBMs “Sfânta Maria” and “Sfânta Ana” will excavate the 6.6 km long underground tunnels, on which the six stations and six interstations of the M6 Metro Line alignment, SOUTH Section, 1 Mai – Tokyo, will be built.

Metrorex continues to build for people, for the city, for Romania, and for a sustainable future!