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
“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.