The Life Cycle Cost of Galvanized Steel Bridges

The above video was presented by Dr. Michael Barker, University of Wyoming & SSSBA Director of Education, at the LatinGalva 2021 virtual conference.

Within the presentation, Dr. Barker makes reference to the following reports:

• Historical Life Cycle Costs of Steel and Concrete Girder Bridges (download)
• Life Cycle Cost of Bridges: Galvanized Steel vs. Concrete – Prepared for US Bridge, Cambridge, Ohio (download)

The following contains a summary (background and conclusions) of the Galvanized Steel vs. Concrete report.

For more information on the study, please see the U.S. Bridge website.

Life Cycle Cost of Bridges – Galvanized Steel vs. Concrete: Background and Conclusions

In 2016, the author published a study titled, Historical Life Cycle Costs of Steel & Concrete Girder Bridges. The primary conclusion from that study was that, notwithstanding the prevailing assumption that concrete bridges are more economical than steel bridges, for typical bridges (steel rolled beam, steel plate girder, concrete box adjacent, concrete box spread and concrete I beam bridges), all were economically competitive.

However, none of the bridges in the study’s database used galvanized beams or girders.  Hot Dip Galvanizing with Zinc (HDG) is an old science but its application to bridges is relatively recent.  US Bridge of Cambridge, OH, which serves secondary highway systems throughout the country and is the sponsor of this study, claims to have been the first to hot dip galvanize entire welded truss bridge sections in 1987.

Since then, the federal government has recommended HDG for bridge designs intended to last a century, a relatively new expectation considering that only a few decades ago the objective was a service life of 50 years.  One reason for this is the increasingly limited funds for local bridge construction and repair. As a result, many counties in the United States now routinely specify galvanized bridges for their longer term economy.  However, until now, no one has produced a study of the measurable financial benefits of HDG. This report attempts to fill that void.

This study has been based on certain assumptions: 

1. All painted bridges used in the original study were HDG  instead of painted.
2. The cost of HDG and modern multi-coat painting systems are roughly the same.
3. HDG eliminates corrosion and most steel maintenance, thereby extending average service life by at least 25 years.

The latter two assumptions reasonably approximate industry experience when using galvanized members.

The general conclusions are that, by the use of HDG for typical steel bridges such as those in the previous study:

• The present value cost of future maintenance is reduced 50%.
• Capitalized Costs are reduced 8.5%.
• Galvanized steel bridges can have Capitalized Costs less than the best concrete alternatives.

Download the full report – Life Cycle Cost of Bridges: Galvanized Steel vs. Concrete – Prepared for US Bridge, Cambridge, Ohio