Our highway and interstate system is a critical component of our nation’s infrastructure and economy. These routes are essential for the transportation of goods and services, for emergency responders, for commuting to work, and for family travel. It is imperative that our highways provide safe travel for all. Highway guardrails are an important safety component of these systems. They typically consist of a galvanized metal rail, treated wood block, treated wood post, and fasteners, although steel blocks and posts can also be used.

Chromated copper arsenate (CCA) has a long history as an EPA-approved wood preservative for numerous applications, including posts and blocks used in guardrail assemblies. Numerous independent studies have shown that CCA is an environmentally safe wood preservative with very minimal leaching.

Dr. Kenneth Brooks wrote in Pressure Treated Wooden Utility Poles and Our Environment, “pressure-treated wood utility poles pose no greater risk to the environment than growing the wheat used to bake your next loaf of bread, and present far less personal risk than driving to your local grocery store to purchase that bread.”  Dr. Brooks’ comment can be expanded to posts because posts and poles will perform similarly environmentally when placed in service. Similarly, Dr. Paul Morris has written, “There are environmental risks associated with everything we do and with all of the material used to construct utility structures. For instance, the leaching of zinc from steel utility poles.”

Environmental Impact: Treated Wood vs. Steel

The Treated Wood Council commissioned an independent study analyzing the environmental impacts associated with the national production, use, and disposal of treated wood and galvanized steel highway guardrail posts. This study used life cycle assessment (LCA) methodologies. The results for treated wood compared to galvanized steel guardrail posts were significant (© Treated Wood Council, 2013).

Key Findings

• Treated wood guardrail posts require less total energy and less fossil fuel than galvanized steel posts.

• Treated wood posts have lower environmental impacts in five of six impact categories:

  • Anthropogenic greenhouse gas emissions

  • Total greenhouse gas emissions

  • Acid rain

  • Ecotoxicity

  • Smog-causing emissions

• Reuse of treated wood guardrail posts for energy recovery can offset fossil fuel use and reduce greenhouse gas levels in the atmosphere.

Conclusion

CCA-treated wood is a critical part of our nation’s infrastructure and economy. It is safe for the environment and has a long history of EPA approval for both environmental and human exposure. The alternatives—steel and concrete—are not renewable and require more energy to produce than CCA-treated wood. Additionally, CCA-treated wood is more cost-effective than other options.

CCA-treated wood benefits both the environment and the economy.