Before we can put the first excavator in the ground, there is a lot of preparatory work. A long process of preliminary studies, archaeological screenings, calculations and decisions lead to the final project that is ready to be built.

But once the project is decided, the contractor is found and the work is ready to start, the first phase is typically a series of preparatory works. There are kilometres of water pipes, sewers, power lines, internet cables, district heating pipes, traffic light cables and much more in the ground below us in a fine-meshed network, and all these pipes and cables must first be moved elsewhere before construction of the metro can begin.

The owners of the individual pipes and cables are responsible for moving them, while we as the developer of the Metro have a coordinating role in ensuring that all schedules and processes meet.

Wire relocations typically take from months to years, depending on where the line will be built and therefore how many lines are buried in the area.

Once the underground pipes and cables have been moved, we are ready to start building the Metro. Around the construction site, we set up the familiar green fences, which are noise-insulating to reduce noise for the neighbours. We also start clearing the site of any vegetation, buildings, asphalt, etc. Some may need to be put back up when the metro construction is finished - this was the case with the statue of the Fisherman's Wife at Gammel Strand when we built the Cityring, for example. These items are moved to a depot where they are safe and secure while we build - or moved to another temporary location by agreement with the municipality.

It is also during this phase that we re-route traffic in agreement with the Road Authority and set up signs, barriers, etc. Inside the construction site, we also set up sheds with crew facilities for the people who will be building the Metro.

Finally, this is also the phase where we set up measuring equipment on selected buildings in the area so that we can continuously measure noise and vibrations from the construction and ensure that we comply with the noise limits set by the authorities. We will continuously post the measurements on our website.

The construction of the Metro starts when we build the walls of the station box. This is one of the noisier activities in construction, where we typically drill secant piles into the ground all the way around the edge where the station box will be.

At the same time, we cast the outer walls of the station.

Although plenty of preliminary surveys have been carried out prior to the secant piling work, you never quite know what you'll find in the way of large stones or obsolete, unmapped underground installations. We deal with these challenges along the way, but it can extend the period of noisy work if we encounter challenges in the ground.

Once the outer walls of the station box are in place, we start excavating the ground where the station room and technical rooms will be located. Many thousands of tonnes of soil are excavated and transported to the soil depot designated by the environmental authorities. For example, the approximately 3.1 million tonnes of soil from the M3 was transported to Nordhavn, where it was used for backfill in one of the municipality's major future urban development areas.

The station box must be continuously stabilised with the concrete cross beams that you know from the metro stations. The beams are cast in reinforced concrete and finally a 'lid' is cast on the station box - the so-called 'top plate'. In order to connect the reinforcement in the beams and top plate to the reinforcement in the cast walls, the concrete in the reinforcement must be removed in places to expose the reinforcement. This is called 'pile caping' and is done with a large hammer that knocks away the concrete in the right places without damaging the reinforcement. Afterwards, water is sprayed under very high pressure to create grooves in the surface so that the new concrete in the beams and top plate bonds better with the existing concrete in the walls.

This work can be very noisy while it's going on, although we try to muffle it as much as possible with covers.

Drilling the tunnels is a very special chapter in the history of the creation of an underground metro. Tunnel boring machines are the largest machines in metro construction - on the M4 Sydhavn project, the machines weighed 620 tonnes and had a length of 142 metres. The tunnel boring machines are almost like small factories that work around the clock while the drilling work is going on - and they are continuously controlled and serviced by 10-15 highly specialised employees. The tunnel boring machines drill approximately 15-20 metres per day.

If you live on top of the upcoming tunnels, you may hear a rumbling beneath you during the week it takes the tunnelling machines to pass through your area. Work trains bring the tunnel elements to the boring machine and take the excavated soil out again.

There is a tradition that tunnel boring machines - like ships - are named before their maiden voyage. During the construction of the M4 Sydhavn, the tunnel boring machines were called Inge and Olivia - named after Inge Lehmann, a geophysicist who discovered the earth's core 100 years ago, and Olivia Nielsen, a prominent figure in the 19th century trade union movement, where she fought to organise female workers. Olivia Nielsens Gade is located in Sydhavnen - and the metro tunnel crosses the street along the way.

Once the station box is made underground and the tunnel boring machines are well underway, we start setting up the stations underground. The station is built from the bottom up towards the surface. During this phase, floors and storeys are poured, room divisions are made (because a station also consists of many technical rooms, emergency exit shafts, etc. Later, escalators, lifts, platform doors, floor and wall cladding, cables, travel card stands and everything else you know from a metro station.

The work is mainly done underground for good reason, so on the surface it's a less noisy phase. However, there will be some travelling to and from the construction site with concrete and other building materials.

As we approach the end of construction - and thus the opening of new metro stations - we are constructing the station sites above ground. At the same time, we are thoroughly testing the entire system.

Station squares are typically municipal squares on a par with the city's other squares and urban spaces, and are designed in collaboration with the municipality.

When we build the station square, we take down the green fences and replace them with lighter wire fences that you can see through. That's why you'll see more activities on the surface - and roads, pavements and cycle paths that will be moved around a bit - so that the square can be ready for the opening and fit in well with the other roads etc. in the area. The work in this phase is similar to regular roadworks, where we build roads, pavements, cycle paths, drainage, paving, planting what needs to be planted and setting up benches etc. depending on how the station square will be designed.