The Weird Reason More Bridges Are About to Fail | Summary and Q&A

TL;DR

Climate change poses a significant threat to bridges, as rising temperatures, increased rainfall, and corrosion from carbonation can compromise their structural integrity.

Key Insights

• 🤕 The average age of bridges in the US is around 45 years old, making many of them susceptible to climate-induced stresses.
• 👻 Expansion joints in bridges, designed to allow for thermal expansion and contraction, can become clogged and fail, compromising structural integrity.
• 🌉 New bridge designs, such as integral abutment bridges, provide better resistance to thermal stress but are more vulnerable to scour.
• 👱 Increased CO2 levels in the air accelerate the corrosion of steel rebar in concrete bridges through the process of carbonation.
• 💩 Solutions to bridge vulnerabilities include leaf-proof designs, counteracting scour with collars or sacrificial piles, and implementing thicker concrete or sealants to protect against carbonation.
• 👷 Legislation and bridge construction standards are gradually incorporating climate resilience measures.

Transcript

I’m guessing that you don’t spend all  that much time thinking about bridges. Even if you cross a few on your daily commute, you probably don’t give any thought  to the fact that tons of steel and concrete are holding you hundreds of  feet in the air, and usually over water. And since there are at least a  million bridges around the world, includin... Read More

Questions & Answers

Q: Why are many bridges vulnerable to climate change?

Most bridges were built before the effects of climate change were understood, and their designs did not account for the current and future impacts of climate crises.

Q: How does thermal stress affect bridge integrity?

When materials are exposed to heat, they expand, potentially causing structural components to no longer fit together properly. Expansion joints help accommodate these changes, but they can become clogged and fail on hotter days.

Q: What is scour, and why does it pose a threat to bridges?

Scour is the erosion of bridge foundations caused by water turbulence. With increased rainfall and flooding due to climate change, scour can occur at a faster rate than predicted, weakening the foundation.

Q: How does carbonation lead to corrosion in bridges?

Carbon dioxide in the air infiltrates concrete, reducing its alkalinity and compromising the protective layer on steel rebar. As a result, the steel rusts much faster, accelerating deterioration.

Summary & Key Takeaways

• Many bridges are aging and were not designed to withstand the effects of climate change.

• Thermal stress, caused by expanding materials in changing temperatures, can lead to bridge failures, especially if expansion joints are blocked.

• Scour, the erosion of bridge foundations due to intensified rainfall and flooding, is a growing concern.

• Corrosion of steel rebar in concrete bridges escalates due to carbonation resulting from increased CO2 levels.