Fail-Safe?: Minnesota Rushes to the Aid of Other Bridges to Reassure Public After Collapse of I-35W

This article reviews some recent steps to improve and make more thorough bridge inspection programs in the aftermath of the collapse of the I-35W Bridge over the Mississippi River in Minneapolis. The inspection cycle for most Minnesota bridges is every two years, with annual inspections for older bridges in poorer repair. The stepped-up inspection process called for by government officials required the state DOT to hire outside help to focus on fracture critical structures, 75 bridges that have a steel structure without redundancy. Professional requirements for bridge inspectors are described, including an in-depth, two-week course that augments on-site experience. Rating systems and even terminology can vary from state to state, so that it is challenging to create a curriculum that can be applied across state boundaries. The most common contributing factors to bridge deterioration are listed. They include traffic, age and weather. Heavy commercial trucks are the most wearing, creating accumulated fatigue over time. Once deterioration starts, it tends to accelerate quickly.