Case Södertälje bridge

Minna Kalajoki


To build a bridge to last with low LCC and reduced carbon footprint


Patented design by Stål & Rörmontage and optimal choice of material


Product grade: Lean Duplex Forta LDX 2101, 15 tonnes sheet material (5 mm and 6 mm) and 43 tonnes quarto plates (10 mm, 15 mm, 20 mm)
Product form: Sheets and quarto plates
Finish: Mill finish 1D

Designed to last

The new pedestrian bridge in Södertälje, some 40 km southwest of Stockholm over the busy E4 motorway, catches the eye. Its design is unique, patented by the company that built it.

“The bridge is made of two pieces, one of them is 36 metres long and the other one 24 metres. Our special, protected design was developed to make the most of the material and also to cut the bridge’s life cycle cost. The design concept is fully scalable for further use”, Peter Månsson, Quality Manager of Stål & Rörmontage, explains.

Stål & Rörmontage designed, built and installed the bridge in record time. It was actually faster to install the new bridge than to dismantle the old wooden bridge, which had lasted only 20 years.


Savings over decades

Lower life cycle cost (LCC) was the key reason why Stål & Rörmontage chose Outokumpu Forta duplex stainless steel for the bridge.

“This bridge has a lifespan of 120 years, with no need for maintenance. In our thinking, the total life cycle costs have to be taken into account, not only the immediate investment costs. The initial cost of a stainless bridge is higher. But at first maintenance check, at approximately 30 years, when a carbon steel bridge has to be repainted and a wooden bridge replaced, stainless pays itself back”, Peter Månsson points out.

With stainless, abrasive blasting and repainting can be replaced by simple cleaning which requires very short traffic closures, if any.

“Outokumpu’s Lean Duplex Forta LDX 2101 was our first hand choice for this project. Long lifespan of the bridge was very important for the municipality as well. Our calculations indicate that, over a reference period of 120 years, wooden bridge costs are 283 % and steel bridge costs 333 % compared to the 100 % of a stainless steel bridge”, Peter Månsson adds.


Simple but sophisticated

Södertälje bridge sits beautifully in the surrounding landscape. Its 10 mm see-through polycarbonate plates on both sides protect from the weather and integrated led lighting on the rails add comfort to its users.

The light yet robust bridge is particularly well-suited to demanding Nordic conditions. Stainless steel, for its high mechanical strength and corrosion resistance, is the optimal material if the bridge is exposed to road traffic or even marine environments. And it looks good, too.


Focus on the environment

Duplex steel releases very low amounts of metal ions to the environment and bridges made of it do not require any environmentally hazardous coating. What is more, Outokumpu’s duplex steel is scrap-based and 100 % recyclable.

“Technical properties of stainless steel are continuously developed. High mechanical strength enables weight reduction which makes building and installation less expensive and more environmentally-friendly in many ways. Weight savings compared to carbon steel may reach 30 %”, Project Sales Manager Tobias Larsson from Outokumpu Stainless AB Avesta/Degerfors (Sweden) adds.

Recommended products and insights

How to build a bridge that saves a fortune

Our expert Andy Backhouse explains how the right grade of stainless steel can create a structure that resists corrosion and minimizes maintenance needs over a typical bridge lifetime.

Stainless steel for bridges

Bridge projects are in a class of their own – just like Outokumpu stainless steel. Marked by harsh environments, heavy lifetime usage and high aesthetic expectations, bridges demand special considerations upfront if they’re to go the distance.


The Forta range contains duplex and other high strength stainless steels that enable thinner structures and weight reduction (measured in Rp0.2 > 400 MPa. PRE 16 to 43).

Quarto plate

For extra thickness or larger dimensions, Outokumpu hot-rolled plates – quarto or heavy plates – are the ideal solution. Because Outokumpu oversees production from melt to market, superior quality and on-time delivery are assured.

Avesta, Sweden

Fueled by a high-octane blend of advanced technology and a long, proud tradition, the Avesta mill showcases precision performance. One of Outokumpu’s fully integrated production sites, Avesta redefines excellence.

Degerfors Quarto Plate, Sweden

Outokumpu’s largest plate mill, Degerfors would be noteworthy for its output alone. But Degerfors is also famed as a leading global manufacturer of tailor-made stainless steel quarto plates.

Recommended reading

Global megatrends article

Taking the sustainable path towards building bridges that endure and inspire


What Nynäshamn bridge tells us about the durability of stainless steel


Bridge the knowledge gap with our product-specific carbon footprint


Materials in bridges: a designer’s perspective


Design standards and sustainability in structural engineering


Welding of stainless steel bridges


New opportunities with modular bridges


Sustainability is driving the adoption of duplex steel

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