The textbook defines risk as “the product of the probability of a harm and the magnitude of harm” (Harris et al. 121). In this essay we will look into The Big Dig ceiling collapse in Boston and the I-35W bridge collapse in Minneapolis as examples of what happens when engineers and inspectors fail to critically evaluate risk, test materials adequately, and question unsafe assumptions.
Chapter 6 of the textbook depicts how engineers traditionally think of harm in quantifiable terms — “loss of life, personal injury or illness, and damage to property or the environment” (Harris et al. 124). But the chapter later broadens this idea using the “capabilities approach,” which argues that risk should also be evaluated by how it affects people’s basic ability to live the life they value (Harris et al. 151–152). When an engineer misjudges risk, they are not simply violating a code. They are restricting someone’s ability to move safely through their world.
According to the book, risk is managed in design by using “rules proven to produce designs consistent with accepted engineering practice” (Harris et al. 124). These codes usually require redundancy and visible failure warnings. This is so that if one part fails, others still hold. The Silver Bridge collapse in 1967 killed 46 people. This led to “more stringent bridge inspection and maintenance requirements” (Harris et al. 124). Yet, the fact that such tragedies continue decades later shows how slowly lessons are learned sometimes. Risk management is not a one-time calculation. It is an ongoing moral obligation.
The text also shows how engineers and the public perceive risk differently. The public does not view risk “simply in terms of expected deaths or injury” but also considers “whether the harm is unacceptably severe, whether a risk is assumed with free and informed consent, or whether the risk is imposed justly” (Harris et al. 152). This shows that engineers should not only perform technical analysis but also communicate risk openly. Silence or overconfidence can be as dangerous as design flaws.
The Big Dig Collapse is a direct example of poor communication of risk and sub-par verification of design. On July 10, 2006, a ceiling panel in Boston’s I-90 connector tunnel fell, which killed one person and injured another. The panel, weighing 26 tons, was held by epoxy bolts that gradually pulled out of the concrete. Investigators later found that the epoxy used was inappropriate for “long-term tensile-loads” and that contractors and inspectors “had failed to properly test the material or consider creep under long-term load conditions” (Harris et al. 211). The National Transportation Safety Board concluded that the failure was a result of systemic failure to assess risk and to verify the long-term performance of critical materials (Harris et al. 211). The engineers should have insisted on long-term load testing. They should have questioned whether the epoxy was suitable for permanent use. Instead, short-term success became an excuse for complacency. A critical attitude toward new materials might have prevented the tragedy.
When the bridge’s important structures have serious deterioration, they require maintenance more frequently. This is when the bridge is referred to as “structurally deficient.” It is important to note that this does not mean that the bridge is unsafe to use at that instance (Harris et al. 212). However, that category should trigger immediate engineering analysis, not bureaucratic delay. As Chapter 6 argues, acceptable risk is not about numbers alone — it is about protecting “the capabilities of people to live the kind of life they value” (Harris et al. 152). When public infrastructure carries daily commuters, the threshold for acceptable risk should be nearly zero.
The I-35W Bridge Collapse in Minneapolis, on August 1, 2007, tells a similar story. The bridge had been rated as structurally deficient with a rating of 4 out of 9 (Harris et al. 212). The failure was traced to undersized gusset plates. These plates were never re-evaluated when the bridge was resurfaced and retrofitted. Inspectors focused mainly on corrosion and cracks but had no procedures for checking design errors in original plans (Harris et al. 212). If the inspection team conducted a more holistic and thorough review, they might have been able to find out the true concern that came from design limitations.
Both the Big Dig and I-35W disasters convey the lesson that risk assessment must be continuous, evidence-based, and ethically founded. Inspections should include design verifications and not just condition surveys. Engineers must have the freedom and responsibility to question prior work and insist on long-term condition testing. And most importantly communication between everyone must be truthful and transparent. The collapses in Boston and Minneapolis are not only engineering failures but failures of moral thought.