Building LA's Earthquake-Proof Bridge

TL;DR

The 6th Street Viaduct in Los Angeles is being replaced due to structural issues and seismic instability, with a new bridge featuring illuminated concrete arches and advanced seismic safety measures.

Transcript

Los Angeles 6th Street Viaduct is one of the most well known bridges in the United States made famous by appearances in countless movies TV shows commercials and music videos the 1066 metre long structure was an engineering marvel when first constructed in 1932 making use of an on-site plant to produce concrete during construction it was later disc... Read More

Key Insights

• 🔉 The 6th Street Viaduct in Los Angeles, known for its appearances in popular media, is being replaced due to structural issues and seismic instability.
• 🌍 Michael Maltzan Architecture won an international design competition to create a new bridge that pays homage to the original structure while enhancing seismic safety.
• 👻 The new bridge features illuminated concrete arches, fewer ground supports, and seismic isolation bearings, which allow for movement during earthquakes while maintaining stability.
• 🆕 The demolition of the original viaduct was followed by the removal of tons of concrete and steel, and the subsequent construction of the new bridge began.
• 😫 The new 6th Street Viaduct, set to be completed in 2020, will serve as a vital link in Los Angeles' road network and provide recreational spaces and community facilities underneath.
• 📽️ The project is the largest bridge project in the city's history, with a cost of $428 million.
• 😣 The bridge's design exceeds the city's strict building codes to ensure it withstands severe earthquakes.

Questions & Answers

Q: What caused the structural issues and cracks in the 6th Street Viaduct?

The high alkali content in the concrete used during construction caused alkali silica reaction, leading to cracks forming throughout the structure.

Q: Why was the 6th Street Viaduct marked for demolition instead of extensive restoration?

Numerous costly restoration attempts were made, but no permanent solution could be found. Additionally, a study revealed the bridge's seismic instability, making demolition necessary.

Q: How does the new bridge pay homage to the original structure?

The new bridge, designed by Michael Maltzan Architecture, features 10 pairs of illuminated concrete arches that reference the earlier bridge while enabling longer spans and fewer ground supports.

Q: How is the new bridge designed to withstand earthquakes?

The new bridge exceeds the latest seismic safety codes and features seismic isolation bearings at the midpoint of its columns, allowing for movement of up to 76 centimeters during an earthquake and absorbing most of the energy.

Summary & Key Takeaways

• The 6th Street Viaduct in Los Angeles, known for its appearances in movies and TV shows, is suffering from cracks due to a high alkali content in its concrete.

• A study revealed that the bridge was seismically unstable and had a high risk of collapse during an earthquake, leading to its demolition.

• The replacement bridge, designed by Michael Maltzan Architecture, features illuminated concrete arches, fewer ground supports, and advanced seismic safety measures.