Successful trials for extending the life of bridges

The bridge in Stöde 

In the LIFEEXT and LIFEEXT2 projects, studies have been done to investigate the possibilities for extending the life of steel bridges by using, among other post-weld treatment methods, HFMI - High Frequency Mechanical Impact. The projects have been managed by Joakim Hedegård and Alexander Lundstjälk at Swerim. 

"50 to 60 per cent of all bridges in the western world are approaching the end of useful service life. So, there is definitely a big demand for cost-effective methods for extending bridge life expectancy,"says Joakim Hedegård. 

Initially, in these research projects, HFMI and other methods were tested in a laboratory environment (LIFEEXT), and then implemented in practice in a bridge renovation project together with Trafikverket (the Swedish Transport Administration) and contractor Svevia (LIFEEXT2). 

Full-scale testing on Stöde bridge 

Due to increased traffic volume and heavy transports, Trafikverket deemed it necessary to raise the load-bearing capacity on a bridge in Stöde, west of Sundsvall. Svevia carried out the work and full-scale testing of HFMI as a reinforcement method was also implemented. The LIFEEXT2 pilot project supported with quality assurance and advice, with very positive outcome. 

"Trafikverket has many bridges that must be raised from a bearing-capacity rating of BK3 to a BK4 rating and, in conjunction, reinforced.  The life extension methods we studied in LIFEEXT and LIFEEXT2 can be good, cost-effective tools in this work," says Hans Pétursson, steel-bridge specialist at Trafikverket. 

"Collaboration has been the key to success in this research project," says Joakim Hedegård, Swerim, emphasising the good collaboration with Chalmers, KTH, participating companies and, of course, Trafikverket and Svevia. 

"It was really rewarding to work together this way. Research at Swerim is always about creating benefit for industry, but I have literally never worked with something as big as this. Society's resources are limited, but our infrastructure needs a lot of attention. So, now it's a matter of finding the smartest solutions, and when it comes to increasing the life expectancy of our steel bridges I think we have succeeded in finding such a solution in this project." 

But, regarding implementation of these methods in large scale, Joakim Hedegård sees a big challenge ahead. 

“We need a new specialist occupation: 'Bridge-life extender'. The engineers will soon have the knowledge, but we need operators who specialise in this. For that, we will require special training. Together with the Welding Commission and HiFit, we are looking at how this can be done and we hope to be able to secure the funding support needed to roll this out to welding instructors throughout Sweden.” 

Participants in the ongoing LIFEEXT2 project are Swerim, Chalmers, KTH, Dekra, TRV, HiFit, Svetskommissionen, Ramböll and Winteria. The project is funded via InfraSweden2030 by Vinnova, Energimyndigheten (the Swedish Energy Agency) and Formas, and with contributions from participating companies and organisations. 

Photo: HFMI treatment (life extension). 
Photo: The bridge in Stöde