Bosco Verticale. Credit: Arup; Bosco Verticale. Credit: Arup;

Bosco Verticale, Milan

How do you engineer a forest in the sky?

Bosco Verticale are two residential towers within Milan’s Porta Nuova area, one of the biggest urban redevelopment project in Europe. The building is placed in Porta Nuova Isola, an area which was historically dedicated to light industrial and craft activities.

The project was set to create a new standard for sustainable housing to contrast Milan's increasing pollution threat. As a new model for urban regeneration, the design creates a biological habitat within a total area of 40,000m2 and includes a total of 900 trees between 3m and 6m in height planted on the terraces up to the 27th floor, along with 5,000 shrubs and 11,000 floral plants. The vast amount of greenery on the building encourages the production of energy. The plants produce oxygen and humidity and absorb CO2 and dust particles thus improving the surrounding environment.

Mitigating the ground vibration

Our engineers delivered the structural and geotechnical design and provided consultancy services on acoustics, vibrations, ground-borne noise and tunneling. As the site lies above the M2 line of the Milan Metro system, Arup designed Bosco Verticale’s structures incorporating advanced solutions that helped mitigating the effects of the existing underground tunnels. 

Our specialists assessed the existing tunnels with desk-studies, vibration surveys and in-situ tests to allow detailed analyses of the structure during the planned construction. We’ve also analysed the behaviour of tunnels for the direct effect of the new buildings, for the construction of the diaphragm walls and excavation and for the indirect loading effect of the towers. 

During the construction of the buildings, we’ve also monitored the tunnels to control any possible unexpected effects and to verify that the real behaviour matched the numerical predictions.

We also provided advanced design solutions to counteract the effects of the two existing railway tunnels by means of a vibration base-isolation system for the main buildings. This solution also provides additional seismic protection.

 

Project Summary


900 trees

5000shrubs

11,000floral plants

Engineering the trees

Engineering the trees

From compact two-room apartments to penthouses and duplexes, the main characteristics of the flats are the balconies, which extend 3.35m outwards to host more than 900 cherry, olive and oak trees and other plants. 

Arup designed the structural stability of the trees through the botanical analysis of the species and their geometry, a detailed wind climate assessment and two different wind tunnel test campaigns to discover how growing them at height would affect the buildings’ structures.


While all the medium and large trees have a safety cable to prevent the tree from falling in case the trunk breaks, the largest trees in those locations most exposed to wind have a safety steel cage that restraints the root-bulb and prevents it from overturning under major windstorms.

Once the trees were planted, some 1,200 ladybirds were released to help improve the site’s ecosystem.

Today, as residents go about their daily lives inside, the flourishing trees help improve air quality, provide shade and reduce noise pollution. We’ve used engineering to help architecture and nature work together. The result is a forest in the air that is as beautiful as it is practical.


Coordinating trees with traditional structures required to account for a live relationship, changing with seasons and climate ” Luca Buzzoni Luca Buzzoni Associate Director at Arup

Bosco Verticale. Credit: Arup Bosco Verticale. Credit: Arup

Award wins

  • Best Tall Building in Europe by the Council on Tall Building and Urban Habitat 2014

  • International Highrise Award (IHP) 2014 for the world’s most innovative highrise building by the City of Frankfurt am Main together with Deutsches Architekturmuseum and DekaBank

  • International Highrise Award 2014 for the world’s most innovative highrise

  • Best Tall Building Worlwide 2015 by the CTBUH in Chicago