Spotlight on Monaco’s Mediterranean expansion

Monaco’s 38,000 residents currently live on just over 2 square kilometres of land – a surface area smaller than New York’s Central Park. With an estimated 2,700 people expected to move to Monaco by 2026, the issue of space has become critical.

For more than 150 years, Monaco has adapted its urban planning to the narrowness of its two squared km territory, which is constrained between mountains and sea.

The Principality is constantly shaping its urban landscape through major structural projects in order to meet the requirements of its demographic growth, economic attractiveness and sustainable development. In the last century, from the 1950s onwards, 20% of the Principality’s surface area was reclaimed from the sea.

To continue to support and accompany its developments and respond to the responsibilities and challenges it faces, Monaco continues to develop the ground area of its territory. The continuing evolution of construction technologies and the new architectural concepts they make possible, allow the development of ever more innovative and daring structures using more efficient and sustainable methods and materials.

That is why the Prince’s Government launched a call for applications in May 2013 for the construction of a new district through an urbanization project at sea.

SAM L’Anse du Portier, with Bouygues Travaux Publics MC, won this tender.

The realization of this project was an architectural and technical challenge. It responds to the Principality’s ambitious energy transition objectives regarding its commitments to reduce greenhouse gas emissions (becoming carbon neutral by 2050) and to the need for growth in a dynamic and modern country.

Part of the challenge was to design and apply construction methods which minimize the impact on the natural environment in agreement with Monaco’s global sustainable development project.

Land reclamation

Land reclamation is not new to Monaco. Since reclaiming its first land in the late 19th century, the country has expanded its territory by over 20% through various expansions. Now it has embarked on a new project to reclaim 6 hectares of residential and commercial space that will accommodate 1,000 residents.

The first phase of the exciting Portier Cove Monaco project and arguably one of the most important – the Portier roundabout, which will act as a gateway to the exciting eco-district – is now complete.

Work on this crucial infrastructure of the Portier Cove Monaco development officially ended on May 13th 2020, some two years after it began. 

The traffic island, which looks more like New York’s iconic Guggenheim Museum than a roundabout, has been acknowledged as the ‘nerve centre of the project’. 

The solutions applied

The layout of the belt composed of 17 caissons on the waterfront did not leave much freedom for its designers. It follows the underwater current that flows through this area. Hence its sinuous and streamlined shape.

On the other hand, to dampen the force of the waves, absorb the power of the water, break the reflection of the wave and reinforce the stability of the structure, solutions had to be worked on to adapt to the specific conditions that characterise ‘100-year waves’.

The backfill was not designed as a mere vertical wall acting as an obstacle to waves. It is a bank with a base 50 metres deep and which extends upwards to -20 metres on a gradual slope. Its top is a plateau on which the caissons are placed and then permanently ballasted.

The ballasting operation doubles their weight to about 20,000 tonnes per caisson.

Perfect team

Van Oord’s flexible fallpipe vessels Nordnes and Stornes were a perfect team for this job, which required installing 900,000 tonnes of small rock, within the scheduled timeframe.

Both vessels have a dynamic positioning system, which automatically maintains the vessel’s position. This eliminated the need of anchoring, which was prohibited on the project site. Besides, these flexible fallpipe vessels are equipped with a large discharging boom, allowing them to install rock over the side behind the seawall. 

In April 2019, the Stornes already installed 125,000 tonnes of rock.

The Stornes loaded rock in Piombino, Italy and the Nordnes in Marseille, France. The schedule was set up so that one of the vessels would be installing rock in Monaco while the other was taking its next load. The interplay between the two resulted in great efficiency. 

Van Oord completed the job in December 2019. 

Verifying the sizing through 3D tests

Complex hydraulic calculations have also been carried out to understand and manage the interaction between the structures and sea power, both in calm and agitated periods.

Basin tests were also necessary to simulate what the calculations could not represent. Two-dimensional tests in a wave flume allow the reflection coefficients of the caissons and the wave overtopping capacities to be determined.

These tests, carried out at the Oceanide laboratory in La Seyne-sur-Mer, France, made it possible to finalize the shape of the Jarlan chambers and the double wave energy dissipation chamber inside the caissons.

Hydraulic calculations based on different scenarios, carried out using the REFONDE software, determine possible agitation in the port d’animation and make it possible to set upsolutions to limit their effect.

Finally, what could not be calculated was measured through 3D tests carried out in Wallingford, England, in the largest hydraulic laboratory in Europe and one of the largest in the world for this type of simulation.

Two objectives of these tests were:

• Checking the stability of the backfill and its breakwaters in the case of extreme swells;

• Checking and measuring water overtoppings above the caissons and in the port d’animation in the event of an extreme storm.

The tests were carried out on a 1:60 scale model in a wave tank.

Cutting edge project

Portier Cove Monaco is the Principality’s most cutting edge project to date.

The $2.4 billion land reclamation development will create more than six hectares of new residences and open spaces, with villas, houses and apartments designed by Valode & Pistre and the Pritzker Prize-winning architect Renzo Piano.

The expected completion date for Mareterra Monaco is 2025, with the construction of the first buildings scheduled for 2022.