Designed by architect Antonio Citterio for the 2015 Expo, the bridges reconnect a previously dilapidated area with the rest of the city. Their five gently curving arches, which are reminiscent of Mediterranean hills, are lightweight and simple.
Lighting designer Metis Lighting, a frequently collaborator with Citterio, complemented the bridges’minimalist design with simple white light on each arch. However, while the visual effect appears simple, the work behind it was one of the designer’s most demanding projects.
Marinella Patetta, a designer with Metis, explained that the project was difficult from the beginning. “The structure is about lightness, permeability and transparency, and we tried to follow these principles with light. The aim was to highlight only the arches and their intrados (undersides), accentuating their sinuous shape. It sounds simple, but it took a lot of work to get very high quality light at all the different angles. We had to integrate the light fittings in the parapet of the walkway.”
This was a challenging geometrical problem, since the fittings were in a straight line, but needed to achieve even illumination along a curved edge. To make things more complex, the arches were not vertical but angled outwards. Using Philips Color Kinetics on the parapet, the designer carefully selected lenses and angles that would achieve the right effect. The lights had to be carefully positioned so that the fittings themselves were concealed.
The project was beset by financial problems, and at one point the city suggested using cheaper lights. However, Metis successfully argued that this substitution would not work. The optic had to be very precise, both for the visual effect and to prevent light pollution.
For Patetta, LED technology was the only option, both because of its performance and durability. Maintenance and vandalism were important considerations, and the chosen fittings have protective glass covers that cannot be removed by pedestrians.
Originally Metis intended to use subtle dynamic lighting, cycling between different colour temperatures of white light, but budget cuts prevented this. Metis settled for a static colour temperature of around 4000K, which Patteta believes perfectly complements the grey colours of the bridges. Metis has successfully ensured that people notice the bridges, not the light fittings, and the architecture now stands out beautifully from its surroundings.