Published in 1/2023 - Movement

Interview

A Bridge to the Future

Essi Oikarinen

The bridge leading from the Turku city centre over the railway line to the Logomo cultural venue was designed as a convertible machine.

A 140-metre glass wall gently curves over the rail yard of the Turku Central Station, offering pedestrians a sheltered route over the railway tracks. Previously, the city of Turku had been divided in two by the river, but with the expansion of the city, the railway line became yet another divider. The nearest bridges are half a kilometre in both directions, so thanks to the new bridge the route from the city’s Market Square to the Logomo cultural venue has been significantly shortened. In the future, the bridge will also be used by passengers using the Turku Central Station, whose main route to the platforms will be via the bridge.

In the spring of 2016, six design teams consisting of engineers, architects and artists competed for the design of the bridge. The entry with the pseudonym ”Jousi” (”Bow”) was chosen as the winner, the jury characterising the design’s expression as ”neutrally complementary, but with an inner strength that radiates out to its surroundings, slowly unfolding”.

The bridge, completed in the autumn of 2021, looks precisely like the illustrations in the competition proposal. The central structure is a six-metre-wide triangular girder, suspended above the railway from inverted L-shaped towers. The actual pedestrian level hangs from the girder.

More photos and drawings of the project →

Tom Cederqvist and Johannes Laiho of Cederqvist & Jäntti Architects, you have been involved in the design of the Logomo bridge throughout the entire seven-year project. It is the first bridge in Finland suspended from stair and lift towers. How did you arrive at that solution?

We discussed how to make the bridge so that it would seem as light as possible and the visual appearance would be based solely on technology that was used to built it. When looking at the bridge, you have to stop and think for some time before figuring out the solution. In the commission we had to be prepared for possible changes in the rail traffic, so it must be possible to easily change the stairs and lift connections without alterations to the bridge itself. Openings in the glass facades can later be made as necessary. The suspended structure also helps in keeping the pedestrian level relatively thin and low, so pedestrians don’t have to climb up very high because of the structure.

Why is the bridge curved?

The shape connects important points on both sides of the railway track. The competition brief required the bridge to be able to continue over Ratapihankatu street, directly to the first floor of the commercial building. The current and planned platforms solution as well as the electric line also influenced the shape and placement of the bridge.

Is designing a bridge over railway tracks different from a bridge over a road?

It was necessary to consider, for example, the impact loads, and due to occasional transportation of toxic materials, ventilation is required for the bridge. Free space between the tracks and the structures of the electric line limited the placement of the bridge structures. Thorough examination was required when moving something even just a bit. Even for the yet unbuilt lifts and stairs, many different versions were drawn up.

The surrounding area is not yet ready in the traditional sense, but the layout of the railway station will change, and the bridge will possibly be extended. What was it like to design such an entity that will undergo changes?

Change and flexibility were the starting points of the entire design. The bridge is modular. It is based on six-metre-long repeating elements. We were able to develop a machine to which parts can be added and which can also be modified using the original recipe. Fabricating a steel bridge is not actually building construction but rather accurate joining of parts that come ready-made from the metal workshop. 

The design is based on only a few visual ideas. The largest task has been to retain the clear-cut design solution. The whole time, there has been a tendency for all kinds of stuff to be added. Managing them was an essential part of the design work. Paying close attention to details proved to be important for the end result.

What was the collaboration like between the architects and the engineers when designing the machine?

One of our roles as architects has been to hold together the architecture, structure and functionality. We tried to control the whole by detailed modelling – the architect’s and engineer’s models were almost identical.

There have been many delays in the bridge project, designers and builders have changed, and the budget has increased. What has the dragging out of the project meant from the architect’s point of view?

It was the sum of many unfortunate coincidences. Due to the prolonged duration of the project, there was some rotation among the main designers.  Whenever people change, tacit information is lost. The structure of the bridge is unique. If one tries to do something new, one will always encounter the challenges typical for a prototype. The City of Turku had raised the bar very high by organising a design competition and they wanted a bridge of high quality. 

Turku’s transport infrastructure has achieved a bit of humorous notoriety due to the Funicular inclined elevator, which seems to be often out of order. What makes the Logomo bridge a successful part of Turku’s transport infrastructure?

Many buildings that have later turned out to be important have received a mixed reception upon completion. The bridge is a long-term investment. We hope that it will become a source of pride for Turku. There are no elements in the bridge that clearly show what era it is from. Timeless architecture will most likely still look good decades from now. As the surrounding areas undergo development, it will be understood that the bridge connection is important. ↙