Helping bridges last longer | foresight.skanska.com
Thinking big

Helping bridges last longer

Large bridges are remarkable pieces of infrastructure that connect communities and improve people’s lives. However, their construction and operation often creates large carbon footprints. One way to reduce the climate impact of existing bridges is to significantly extend their lifespans, getting more value from the initial carbon investment.

Just about everything about New York’s George Washington Bridge is impressive. The 1.45-kilometer structure across the Hudson River is the world’s busiest vehicular bridge and it’s also home to one of the world’s largest US flags. Now, a Skanska team is undertaking an appropriately impressive feat – working to extend the lifespan of key bridge components by many decades.

In the latest episode of our Shaping Sustainable Places podcast, we meet two individuals focused on extending the lives of two of the world’s best-known bridges. Jen Billand is Senior Project Manager on a Skanska project to rehabilitate the famous George Washington Bridge, which links northern Manhattan with New Jersey. Bengt Hergart, meanwhile, is the Property Director for Øresundbro Konsortiet, the consortium which owns and operates the Öresund Bridge linking Sweden and Denmark.

 

System to reduce erosion

 

Jen explains that “the George” has two decks over which some 300,000 vehicle journeys are completed each day. The bridge was opened in 1927, and Skanska has been tasked by the Port Authority of New York and New Jersey with carrying out remediation and renovation work. This includes replacing 592 steel suspension ropes and improving access for cyclists and pedestrians.

 

We are also installing a new dehumidification system that will blow dry air across the four main cables that support the bridge, helping to reduce rust and other forms of corrosion. Jen says this should extend the life of the cables – each of which weighs 28,000 tons – by 80 years, ensuring the bridge is able to serve local communities up to and past 2100.

 

She says a key challenge has been undertaking the project with minimal impacts on users of the busy bridge. Only one lane can be closed during daytime operations, and work involving multiple lane closures can only be conducted at night.

 

Working to double the bridge’s lifespan

 

Across the Atlantic in Scandinavia, the Øresund Bridge links the Danish city of Copenhagen with the Swedish city of Malmö. Completed in 2000 by a consortium including Skanska, the structure comprises 7.8 kilometers of elevated bridge, a four kilometer artificial island and four kilometers of underground tunnel. The top bridge deck has space for four traffic lanes, with two rail tracks on the bottom deck.

 

Bengt Hergart says while the plan at the time of construction was for the bridge to have a 100-year lifespan, the consortium which operates it now plans to extend that lifespan to 200 years. The aim is to significantly reduce the bridge’s climate impact by extending the benefit derived from the initial and ongoing carbon investment. Bengt says this work involves identifying the structures that determine the bridge’s life and then identifying threats to them. The next stage is to establish which parts can be repaired and then developing and implementing a maintenance approach.

 

Bengt says other measures to improve the bridge’s sustainability include reducing the power required to run it. A 45-percent reduction in power usage has been achieved since 2000 and two solar energy plants now help to power the operation.

 

You can tune in, listen and subscribe to the podcast on Spotify, Apple Podcasts or Google Podcasts.